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Solar System/Solar System

One of the most difficult and controversial fields of astronomy is the study of the way in which the Solar System was formed, as well as its past and its future evolution.

The Solar System, or more particularly, its larger bodies - all the planets with their satellites, orbit in the Sun close to one plane known as the ecliptic which is defined as the plane in which the Earth orbits, and all move in the same direction. It is helpful to remember that an observer viewing this from a position above the plane of the ecliptic, or from the direction of the terrestrial north pole, would see the planets move around the Sun in an counter-clockwise direction, also referred to as prograde motion. All the planets and their major satellites rotate in an counter-clockwise direction on their axis, with the exception of Venus and Uranus which, because of the position of their axes shows that they experienced some cataclysmic event in their far-off past.

The distance of the planets and their satellites from the Sun increases regularly as described by the Titius-Bode law. This regularity in the movements of revolution and rotation, and the disk shape of the whole system suggested a hypothesis to Immanuel Kant as long ago as 1755, and to Pierre-Simon de Laplace in 1796: that the Sun and the planets had been formed out of a cloud of rotating gas as a result of the combined action of the force of gravity and centrifugal force. This cloud has historically always been known as the "solar nebula."

Another aspect that must be borne in mind is the distribution of density within the system: the terrestrial planets have higher densities, varying from approximately 5.5 and 3.9 times the density of water, while the giants planets have consistently lower densities, varying from 0.7 to 1.6 times the density of water.

The place of the Solar System in the universe
The universe contains an estimated 100 billion galaxies, of which our Milky Way is one. The Milky Way itself contains an estimated 100 billion stars, of which our Sun is one. The Milky Way is a spiral galaxy with a radius of around 50,000 light-years (a light-year being the distance that light travels in one year), and the Sun and its solar system are around 30,000 light-years from the center of the galaxy.

The Age of the Solar System
Based on the age of the oldest meteorites, it has been calculated that the Solar System was formed approximately 4.5 billion years ago. Chondrules, spheres of crystal present in chondrite-type meteorites, contain radioactive elements and the proportions of these enable us to measure the time that has elapsed from the moment in which the crystals solidified: this time lapse provides us with an indication of the age of the Solar System.

A group of research scientists at the Institute of Physical Earth Sciences in Paris has carried out very precise measurements of the relationship that exists in certain phosphates between radioactive uranium-238 and the element which derives from it, lead 206. As these crystals are rich in uranium but have virtually no lead in their natural state, the lead isotope present in the phosphates has to result from the decay of the uranium. Working from these measurements, radiometric dating means that we can calculate the age of the crystals at about 4.56 billion years.

The Sun and the Solar System
The sun is the only star in our solar system. The sun in the centre of our solar system is a medium sized star. The temperature at its surface is about 6000 degree C. Its size is so big that it could hold within itself 13 lakh earths like ours. All the objects around the sun revolve around it because of its gravitational force. Given the close resemblance in physical structure and chemical composition of the stars and particularly of those of solar type, it is a reasonable assumption that the Sun was formed in the same way as stars of later generations, those whose formation present-day observational techniques make it possible to witness. By the description "stars of the solar type" is meant those stars which have approximately the same mass as the Sun. The main physical features of a star and its evolution depend on its mass, as do the phases of its life: formation through the contraction of a cloud of dust and gas; maturity, when the star emits constant radiation for a length of time: the smaller the star, the longer the duration; and the star's end, with variations in radius and temperature and phenomena which may be more or less violent. It would appear that stars form from clouds of gas and dust, those of recent formation still being surrounded by these. The subsequent stages of stellar evolution are sufficiently well-known to make it possible to calculate their ages to within a very close approximation.

How a star is formed
Of all the phases of a star's life, we know least about its formation. These clouds have very low temperatures and are very opaque; as a result they radiate only in the far-infrared which the terrestrial atmosphere absorbs completely, preventing us from seeing what is happening inside the cloud. As a result of observations from space using the IRAS (Infrared Astronomical Satellite) and data from microwave radio-astronomy which can even penetrate the opaque dust clouds, it has been possible to witness the first phases of condensation of protostars from the interstellar medium. This has led to the discovery that the protostar contracts and the matter accretes onto its equatorial region, while at the same time it expels matter violently along the two opposing directions of its polar axis. In this way a disk forms on the equatorial plane. The presence of a disk of solid matter in stars that have already formed was established by the same satellite but it is also possible to discern this from Earth if the image of the star is occulted with an opaque disk, so that the weak luminosity of the disk is not overwhelmed by the predominant stellar brilliance. These observations enable us to conclude that the young Sun must also have been surrounded by a disk of gas and dust: the solar nebula hypothesized by Kant and Laplace two centuries ago.

According to stellar evolutionary theories, the Sun took approximately 50 million years to reach the phase of stability in its evolution, that is to say, to reach its present values of radius and surface temperature and to radiate, at any given moment, the same quantity of energy that it emits today. Based on these same theories, it has been estimated that these values will remain virtually unchanged for another 5 billion years.

Composition of the stellar nebula
Dust represents only 2% of the stellar nebula mass; the remainder is made up in the following proportions: gas, of which 78% is accounted for by hydrogen atoms, 20% by helium atoms and 2% by all the other elements. The dust accounts for the largest percentage of the heavier elements which are present in planetary conformation: carbon, oxygen, iron, silicon, magnesium. The denser clouds contain between 10,000 and one million molecules per cubic centimeter and have temperatures of approximately 10 degrees Kelvin, the equivalent of 263 C (440 F) below zero. They are unstable because at such low temperatures the force of gravity is greater than the thermal pressure exerted by the gas and dust particles.

Origins
Of the numerous theories put forward to explain how the planets were formed, only two are still considered acceptable, although both of them pose many unsolved problems: the first is the planetesimal or accumulation theory, and the second is the protoplanetary or unstable disk theory. How can the formation of a planet from a disk of dust with particles measured in micrometers be explained? It is worth looking at the two possible answers.

Formation through accretion
This is the most widely accepted hypothesis to be formulated to date. The particles collided with each other and stuck together, leading to processes known as "coagulation" and, subsequently, "accumulation" or "accretion." In this way larger bodies grew from the granules which collected into yet bigger, solid bodies, until they formed terrestrial planets and the nuclei of the giant planets. The gases and dust remained closely intermingled for as long as the turbulent movements typical of the interstellar medium continued in the solar nebula. As the turbulence in the solar nebula diminished, the particles began a process of sedimentation, accumulating towards the central plane of the nebula, forming a very thin disk. Given the relatively high density, it is estimated that the sedimentation process was very quick, perhaps as fast as a thousand years. As the sedimentation process progressed, the mass of the thin disk became unstable and the disk broke up into a large number of solid bodies, each having a diameter of approximately 1 kilometer (.62 miles), called planetesimals. It is estimated that approximately a thousand billion of these existed, orbiting around the Sun, within the region encompassing the orbit of Mars.

Definition of a planet

The official definition of a solar "planet" (due to a 2006 resolution of the International Astronomical Union) is "a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit." By this definition the Sun has eight planets: in increasing order of distance from the Sun, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

title: Solar System/Solar System


text:
Solar System/The Sun

Galactic orbit
The Sun orbits the center of its galaxy, the Milky Way, about once every 240 million years.

Rotation
The Sun rotates relative to the distant stars once every 25.05 Earth-days at its equator and once every 34.3 Earth-days at the poles.

Physical characteristics

Mass: 2,000,000,000,000,000,000,000,000,000 tons [2 × 1027 tons], or about 330,000 times the mass of the Earth.

Diameter: 870,000 miles [1.4 million km]

Age: 4.5 billion years

Average Distance from the Earth: 93 million miles [149.6 million km]

Luminosity: 390 quintillion megawatts

Composition: 91.2 % hydrogen, 8.7 % helium, 0.1 % other chemical elements

Surface Temperature: 10,000 degrees Fahrenheit [5,500 degrees Celsius]

Temperature at Core: 25 million degrees Fahrenheit [15 million degrees Celsius]

Core Density: 12 times that of solid lead

Sunspots and faculae
Sunspots are relatively dark areas on the radiating 'surface' (photosphere) of the Sun where intense magnetic activity inhibits convection and cools the photosphere. Faculae are slightly brighter areas that form around sunspot groups as the flow of energy to the photosphere is re-established and both the normal flow and the sunspot-blocked energy elevate the radiating 'surface' temperature. Scientists have speculated on possible relationships between sunspots and solar luminosity since the historical sunspot area record began in the 17th century.[22][23] Correlations are now known to exist with decreases in luminosity caused by sunspots (generally < - 0.3 %) and increases (generally < + 0.05 %) caused both by faculae that are associated with active regions as well as the magnetically active 'bright network'.[24] Modulation of the solar luminosity by magnetically active regions was confirmed by satellite measurements of total solar irradiance (TSI) by the ACRIM1 experiment on the Solar Maximum Mission (launched in 1980).[24] The modulations were later confirmed in the results of the ERB experiment launched on the Nimbus 7 satellite in 1978.[25] Sunspots in magnetically active regions are cooler and 'darker' than the average photosphere and cause temporary decreases in TSI of as much as 0.3 %. Faculae in magnetically active regions are hotter and 'brighter' than the average photosphere and cause temporary increases in TSI. The net effect during periods of enhanced solar magnetic activity is increased radiant output of the sun because faculae are larger and persist longer than sunspots.

There had been some suggestion that variations in the solar diameter might cause variations in output. But recent work, mostly from the Michelson Doppler Imager instrument on SOHO, shows these changes to be small, about 0.001% (Dziembowski et al., 2001).

Various studies have been made using sunspot number (for which records extend over hundreds of years) as a proxy for solar output (for which good records only extend for a few decades). Also, ground instruments have been calibrated by comparison with high-altitude and orbital instruments. Researchers have combined present readings and factors to adjust historical data. Other proxy data — such as the abundance of cosmogenic isotopes — have been used to infer solar magnetic activity and thus likely brightness.

Sunspot activity has been measured using the Wolf number for about 300 years. This index (also known as the Zürich number) uses both the number of sunspots and the number of groups of sunspots to compensate for variations in measurement. A 2003 study by Ilya Usoskin of the University of Oulu, Finland found that sunspots had been more frequent since the 1940s than in the previous 1150 years.[26]

Granulation
Granules on the photosphere of the Sun are caused by convection currents (thermal columns, Bénard cells) of plasma within the Sun's convective zone. The grainy appearance of the solar photosphere is produced by the tops of these convective cells and is called granulation.

The rising part of the granules is located in the center where the plasma is hotter. The outer edge of the granules is darker due to the cooler descending plasma. In addition to the visible appearance, Doppler shift measurements of the light from individual granules provides evidence for the convective nature of the granules.

A typical granule has a diameter on the order of 1,000 kilometers and lasts 8 to 20 minutes before dissipating. Below the photosphere is a layer of "supergranules" up to 30,000 kilometers in diameter with lifespans of up to 24 hours.

Solar prominences
A prominence is a large, bright feature extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's corona. While the corona consists of extremely hot ionized gases, known as plasma, which do not emit much visible light, prominences contain much cooler plasma, similar in composition to that of the chromosphere. A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months. Some prominences break apart and give rise to coronal mass ejections. Scientists are currently researching how and why prominences are formed.

A typical prominence extends over many thousands of kilometers; the largest on record was observed by the Solar and Heliospheric Observatory (SOHO) in 1997 and was some 350,000 km (216,000 miles) long – roughly half the radius of the Sun or 28 times the diameter of the Earth. The mass contained within a prominence is typically on the order of 100 billion tonnes of material.

When a prominence is viewed from a different perspective so that it is against the sun instead of against space, it appears darker than the surrounding background. This formation is instead called a solar filament. It is possible for a projection to be both a filament and a prominence. Flocculi (plural of flocculus) is another term for these filaments, and dark flocculi typically describes the appearance of solar prominences when viewed against the solar disk in certain wavelengths.

Solar flares

A solar flare is a large explosion in the Sun's atmosphere that can release as much as 6 × 1025 joules of energy. The term is also used to refer to similar phenomena in other stars, where the term stellar flare applies.

Solar flares affect all layers of the solar atmosphere (photosphere, corona, and chromosphere), heating plasma to tens of millions of kelvins and accelerating electrons, protons, and heavier ions to near the speed of light. They produce radiation across the electromagnetic spectrum at all wavelengths, from radio waves to gamma rays. Most flares occur in active regions around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. If a solar flare is exceptionally powerful, it can cause coronal mass ejections.

X-rays and UV radiation emitted by solar flares can affect Earth's ionosphere and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb operation of radars and other devices operating at these frequencies.

Solar flares were first observed on the Sun by Richard Christopher Carrington and independently by Richard Hodgson in 1859 as localized visible brightenings of small areas within a sunspot group. Stellar flares have also been observed on a variety of other stars.

The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly "active" to less than one each week when the Sun is "quiet". Large flares are less frequent than smaller ones. Solar activity varies with an 11-year cycle (the solar cycle). At the peak of the cycle there are typically more sunspots on the Sun, and hence more solar flares.

The solar corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. The Latin root of the word corona means crown.

During a total solar eclipse, the solar corona can be seen with the naked eye. The high temperature of the corona gives it unusual spectral features, which led some to suggest, in the 19th century, that it contained a previously unknown element, "coronium". These spectral features have since been traced to highly ionized Iron (Fe-XIV) which indicates a plasma temperature in excess of 106 kelvin.

Light from the corona comes from three primary sources, which are called by different names although all of them share the same volume of space. The K-corona (K for kontinuierlich, "continuous" in German) is created by sunlight scattering off free electrons; Doppler broadening of the reflected photospheric absorption lines completely obscures them, giving the spectral appearance of a continuum with no absorption lines. The F-corona (F for Fraunhofer) is created by sunlight bouncing off dust particles, and is observable because its light contains the Fraunhofer absorption lines that are seen in raw sunlight; the F-corona extends to very high elongation angles from the Sun, where it is called the Zodiacal light. The E-corona (E for emission) is due to spectral emission lines produced by ions that are present in the coronal plasma; it may be observed in broad or forbidden or hot spectral emission lines and is the main source of information about the corona's composition.

The solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 10 and 100 eV. The stream of particles varies in temperature and speed over time. These particles can escape the Sun's gravity because of their high kinetic energy and the high temperature of the corona.

The solar wind creates the heliosphere, a vast bubble in the interstellar medium that surrounds the solar system. Other phenomena include geomagnetic storms that can knock out power grids on Earth, the aurorae (northern and southern lights), and the plasma tails of comets that always point away from the Sun.

Sunspots
Sunspots are temporary phenomena on the surface of the Sun (the photosphere) that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection, forming areas of reduced surface temperature. Although they are at temperatures of roughly 3,000–4,500 K (4,940–7,640 °F), the contrast with the surrounding material at about 5,780 K leaves them clearly visible as dark spots, as the intensity of a heated black body (closely approximated by the photosphere) is a function of T (temperature) to the fourth power. If the sunspot were isolated from the surrounding photosphere it would be brighter than an electric arc. Sunspots expand and contract as they move across the surface of the sun and can be as large as 80,000 kilometers (49,710 mi) in diameter, making the larger ones visible from Earth without the aid of a telescope.

Manifesting intense magnetic activity, sunspots host secondary phenomena such as coronal loops and reconnection events. Most solar flares and coronal mass ejections originate in magnetically active regions around visible sunspot groupings. Similar phenomena indirectly observed on stars are commonly called starspots and both light and dark spots have been measured.

The study of solar physics
Solar physics is the study of our Sun. It is a branch of astrophysics that specializes in exploiting and explaining the detailed measurements that are possible only for our closest star. It intersects with many disciplines of pure physics, astrophysics, and computer science, including fluid dynamics, plasma physics including magnetohydrodynamics, seismology, particle physics, atomic physics, nuclear physics, stellar evolution, space physics, spectroscopy, radiative transfer, applied optics, signal processing, computer vision, and computational physics.

Because the Sun is uniquely situated for close-range observing (other stars cannot be resolved with anything like the spatial or temporal resolution that the Sun can), there is a split between the related discipline of observational astrophysics (of distant stars) and observational solar physics. The Solar Physics Division of the American Astronomical Society boasts about 600 members (in 2008), compared to several thousand in the parent organization.

A major thrust of current (2009) effort in the field of solar physics is integrated understanding of the entire solar system including the Sun and its effects throughout interplanetary space within the heliosphere and on planets and planetary atmospheres. Studies of phenomena that affect multiple systems in the heliosphere, or that are considered to fit within a heliospheric context, are called heliophysics, a new coinage that entered usage in the early years of the current millennium.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Solar System/The Sun


text:
Solar System/Mercury

Mercury is the smallest planet and the closest planet to the Sun. With a diameter of just 4879.4 kilometers (38% of that of Earth), it is smaller than the two largest planetary moons in the solar system — Ganymede of Jupiter and Titan of Saturn. Mercury has no moons. Mercury and Venus are the only two planets with zero oblateness: its polar diameter is the same as its equatorial diameter. Mercury is one of the four terrestrial planets (planets with a solid surface). If you were standing on Mercury, you would weigh just 38% of what you weigh on Earth.

Orbit

Mercury orbits the Sun once every 87.97 Earth-days, with an orbital eccentricity of 0.21 — far greater than that of any other planet. As a result of this eccentricity, the planet moves notably faster near perihelion (closest point to the Sun) than at aphelion (farthest point from the Sun). Mercury's distance from the Sun varies during its elliptical orbit from 0.31 AU (Earth-Sun distances) at perihelion to 0.47 AU at aphelion, with an average over the entire orbit of 0.39 AU.

Rotation
Mercury is unique in having essentially no axial tilt whatsoever — its tilt is 0.00°. It rotates prograde (in the direction of its orbit around the Sun) about its axis relative to the distant stars once every 58.65 Earth-days. Because its orbital period is not substantially greater than its rotational period (almost exactly 1.5 times as great), Mercury is the only planet on which a solar day (noon to noon) lasts for more than one local year — specifically, a solar day lasts for almost precisely two solar orbits. Furthermore, the fact that the highly elliptical orbit causes the planet to speed up and slow down over the course of the orbit, combined with the similarity in the lengths of the rotational period and orbital period, results in the Sun temporarily reversing direction across the sky when the planet is near perihelion. This occurs because near perihelion the planet is actually revolving around the Sun faster than it is rotating. Mercury is the only planet where this happens, and there are certain places on the planet (where perihelion occurs around sunrise) where the Sun rises temporarily (in the east), reverses direction and sets temporarily in the east, and then rises for good, while there are other places (where perihelion occurs around sunset) where the Sun sets temporarily (in the west), reverses direction and temporarily rises in the west, and then sets for good.

Atmosphere
The mean surface temperature of Mercury is 442.5 K,[3] but it ranges from 100 K to 700 K[44] due to the absence of an atmosphere and a steep temperature gradient between the equator and the poles. The subsolar point reaches about 700 K during perihelion then drops to 550 K at aphelion.[45] On the dark side of the planet, temperatures average 110 K.[46] The intensity of sunlight on Mercury’s surface ranges between 4.59 and 10.61 times the solar constant (1,370 W·m−2).[47]

Despite the generally extremely high temperature of its surface, observations strongly suggest that ice exists on Mercury. The floors of deep craters at the poles are never exposed to direct sunlight, and temperatures there remain below 102 K; far lower than the global average.[48] Water ice strongly reflects radar, and observations by the 70 m Goldstone telescope and the VLA in the early 1990s revealed that there are patches of very high radar reflection near the poles.[49] While ice is not the only possible cause of these reflective regions, astronomers believe it is the most likely.[50]

The icy regions are believed to contain about 1014–1015 kg of ice,[51] and may be covered by a layer of regolith that inhibits sublimation.[52] By comparison, the Antarctic ice sheet on Earth has a mass of about 4 × 1018 kg, and Mars' south polar cap contains about 1016 kg of water.[51] The origin of the ice on Mercury is not yet known, but the two most likely sources are from outgassing of water from the planet’s interior or deposition by impacts of comets.[51]

Mercury is too small for its gravity to retain any significant atmosphere over long periods of time; however, it does have a "tenuous surface-bounded exosphere"[53] containing hydrogen, helium, oxygen, sodium, calcium, potassium and others. This exosphere is not stable—atoms are continuously lost and replenished from a variety of sources. Hydrogen and helium atoms probably come from the solar wind, diffusing into Mercury’s magnetosphere before later escaping back into space. Radioactive decay of elements within Mercury’s crust is another source of helium, as well as sodium and potassium. MESSENGER found high proportions of calcium, helium, hydroxide, magnesium, oxygen, potassium, silicon and sodium. Water vapor is present, released by a combination of processes such as: comets striking its surface, sputtering creating water out of hydrogen from the solar wind and oxygen from rock, and sublimation from reservoirs of water ice in the permanently shadowed polar craters. The detection of high amounts of water-related ions like O+, OH-, and H2O+ was a surprise.[54][55] Because of the quantities of these ions that were detected in Mercury's space environment, scientists surmise that these molecules were blasted from the surface or exosphere by the solar wind.[56][57]

Sodium, potassium and calcium were discovered in the atmosphere during the 1980–1990s, and are believed to result primarily from the vaporization of surface rock struck by micrometeorite impacts.[58] In 2008 magnesium was discovered by MESSENGER probe.[59] Studies indicate that, at times, sodium emissions are localized at points that correspond to the planet's magnetic poles. This would indicate an interaction between the magnetosphere and the planet's surface.[60]

Internal Structure
Mercury is one of four terrestrial planets in the Solar System, and is a rocky body like the Earth. It is the smallest planet in the Solar System, with an equatorial radius of 2,439.7 km.[3] Mercury is even smaller—albeit more massive—than the largest natural satellites in the Solar System, Ganymede and Titan. Mercury consists of approximately 70% metallic and 30% silicate material.[14] Mercury's density is the second highest in the Solar System at 5.427 g/cm³, only slightly less than Earth’s density of 5.515 g/cm³.[3] If the effect of gravitational compression were to be factored out, the materials of which Mercury is made would be denser, with an uncompressed density of 5.3 g/cm³ versus Earth’s 4.4 g/cm³.[15]

Mercury’s density can be used to infer details of its inner structure. While the Earth’s high density results appreciably from gravitational compression, particularly at the core, Mercury is much smaller and its inner regions are not nearly as strongly compressed. Therefore, for it to have such a high density, its core must be large and rich in iron.[16]

 * 1) Crust—100–300 km thick
 * 2) Mantle—600 km thick
 * 3) Core—1,800 km radius

Geologists estimate that Mercury’s core occupies about 42% of its volume; for Earth this proportion is 17%. Recent research strongly suggests Mercury has a molten core.[17][18] Surrounding the core is a 500–700 km mantle consisting of silicates.[19][20] Based on data from the Mariner 10 mission and Earth-based observation, Mercury’s crust is believed to be 100–300 km thick.[21] One distinctive feature of Mercury’s surface is the presence of numerous narrow ridges, and these can extend up to several hundred kilometers. It is believed that these were formed as Mercury’s core and mantle cooled and contracted at a time when the crust had already solidified.[22]

Mercury's core has a higher iron content than that of any other major planet in the Solar System, and several theories have been proposed to explain this. The most widely accepted theory is that Mercury originally had a metal-silicate ratio similar to common chondrite meteors, thought to be typical of the Solar System's rocky matter, and a mass approximately 2.25 times its current mass.[23] However, early in the Solar System’s history, Mercury may have been struck by a planetesimal of approximately 1/6 that mass and several hundred kilometers across.[23] The impact would have stripped away much of the original crust and mantle, leaving the core behind as a relatively major component.[23] A similar process has been proposed to explain the formation of Earth’s Moon (see giant impact theory).[23]

Alternatively, Mercury may have formed from the solar nebula before the Sun's energy output had stabilized. The planet would initially have had twice its present mass, but as the protosun contracted, temperatures near Mercury could have been between 2,500 and 3,500 K (Celsius equivalents about 273 degrees less), and possibly even as high as 10,000 K.[24] Much of Mercury’s surface rock could have been vaporized at such temperatures, forming an atmosphere of "rock vapor" which could have been carried away by the solar wind.[24]

A third hypothesis proposes that the solar nebula caused drag on the particles from which Mercury was accreting, which meant that lighter particles were lost from the accreting material.[25] Each hypothesis predicts a different surface composition, and two upcoming space missions, MESSENGER and BepiColombo, both aim to make observations to test them.[26][27]

Mariner 10's "Sail Power"
The first spacecraft to visit Mercury was NASA’s Mariner 10 (1974–75).[12] The spacecraft used the gravity of Venus to adjust its orbital velocity so that it could approach Mercury, making it both the first spacecraft to use this gravitational “slingshot” effect and the first NASA mission to visit multiple planets.[120] Mariner 10 provided the first close-up images of Mercury’s surface, which immediately showed its heavily cratered nature, and revealed many other types of geological features, such as the giant scarps which were later ascribed to the effect of the planet shrinking slightly as its iron core cools.[123] Unfortunately, due to the length of Mariner 10's orbital period, the same face of the planet was lit at each of Mariner 10’s close approaches. This made observation of both sides of the planet impossible,[124] and resulted in the mapping of less than 45% of the planet’s surface.[125]

On March 27, 1974, two days before its first flyby of Mercury, Mariner 10's instruments began registering large amounts of unexpected ultraviolet radiation near Mercury. This led to the tentative identification of Mercury's moon. Shortly afterward, the source of the excess UV was identified as the star 31 Crateris, and Mercury's moon passed into astronomy's history books as a footnote.

The spacecraft made three close approaches to Mercury, the closest of which took it to within 327 km of the surface.[126] At the first close approach, instruments detected a magnetic field, to the great surprise of planetary geologists—Mercury’s rotation was expected to be much too slow to generate a significant dynamo effect. The second close approach was primarily used for imaging, but at the third approach, extensive magnetic data were obtained. The data revealed that the planet’s magnetic field is much like the Earth’s, which deflects the solar wind around the planet. However, the origin of Mercury’s magnetic field is still the subject of several competing theories.[127]

On March 24, 1975, just eight days after its final close approach, Mariner 10 ran out of fuel. Since its orbit could no longer be accurately controlled, mission controllers instructed the probe to shut down.[128] Mariner 10 is thought to be still orbiting the Sun, passing close to Mercury every few months.[129]

title: Solar System/Mercury


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Solar System/Venus

Venus, named after the Roman goddess of love, is often known as the Morning Star or Evening Star. This is because it reaches its brightest just before sunrise or soon after sunset. It is the second closest planet to the Sun, after Mercury. Venus has no moons. Its diameter of 12104 km is 0.95 times that of Earth; Venus is the sixth largest planet and the second largest of the four terrestrial planets. If you were standing on Venus, you would weigh 90% of what you weigh on Earth.

Orbit

Venus orbits the Sun once every 224.70 Earth-days in the most nearly circular orbit of any planet. Its average distance from the Sun is 0.723 AU (astronomical units, meaning Earth-Sun distances).

Rotation
The rotational characteristics of Venus are interesting and unique. It rotates retrograde (that is, in the opposite direction from its revolution around the Sun), so the Sun rises in the west and sets in the east. The only other planet with retrograde rotation is Uranus, but whereas Uranus is tipped over by almost 90°, Venus has only a very slight tilt — the smallest axial tilt of any planet except Mercury. Venus rotates once relative to the stars every 243.02 Earth-days, a rotational period that is far longer than that of any other planet; its equatorial rotational velocity of 6.52 km per hour is far slower than that of any other planet. Because of the combination of an orbital period of 224.70 Earth-days and a retrograde rotational period of 243.02 Earth-days, a solar day (noon to noon) on Venus lasts for about 116.8 Earth-days, and it has about 1.9 solar days per orbital period.

Physical Characteristics

Venus is a rocky planet, similar in size to the Earth. We have little data on its interior but we think it is likely to be similar to Earth (that is, have a distinct core, mantle and crust). Unlike Earth there is no observable plate movement.

Atmosphere

Venus has an atmosphere comprised of 96.5% carbon dioxide and 3.5% nitrogen. This high level of CO2 creates a "greenhouse effect". The surface atmospheric pressure is nearly 100 times greater than Earth's, equivalent to being 1 km underwater on Earth.

The amount of CO2, and the clouds of sulphur dioxide, create a huge greenhouse effect. Venus is hotter than Mercury despite receiving only one quarter of the energy from the Sun that Mercury does. Typical temperatures are 480 C, despite Venus not being the closest planet to Sun.

Venus once had liquid water until the last 800 million years ago.

The Surface

Most of Venus's surface is smooth plains, with two areas of highlands. The highest mountain, Maxwell Montes, rises 11 km above the surface.

title: Solar System/Venus


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Solar System/Earth

Earth is the third planet from the Sun and has a diameter of 12,756 kilometers, making it the fifth largest planet. It is the only place in the universe where at this time life is known to exist. Earth is one of the four terrestrial planets (planets having a solid surface).

Shape
The diameter of the Earth at the poles is 44 kilometers less than its diameter at the equator.

Orbit
The orbit is nearly circular, with an eccentricity of only 0.0167. Earth orbits the Sun once every 365.2422 sidereal days (rotations relative to the distant stars) at an average distance of 149,597,870 kilometers, and this distance is defined as one AU (astronomical unit). This distance is often expressed approximately in terms of miles as 93 million miles. Earth is at its closest to the Sun each year (that is, is at perihelion) at a time in the range January 2 to January 5, and is farthest from the Sun (is at aphelion) at a time in the range July 4 to July 7. Light from the Sun takes an average of 499 seconds (8 minutes 19 seconds) to get to Earth.

Rotation
The Earth rotates prograde (in the same direction as it travels around the Sun) relative to the distant stars once every 23 hours 56 minutes 4 seconds. Since the Earth is traveling around the Sun during this time, it takes an extra 3 minutes 56 seconds to complete a rotation relative to the Sun; so the solar day is 24 hours long. (Indeed, the "hour" is defined as 1/24 of a solar day.)

Earth's axis is tilted by 23.45° relative to the perpendicular of its orbital plane. This tilt is what causes seasons to occur on Earth. (Since Earth's orbit is virtually circular, the minor variations in the distance from the Sun are not the cause of the seasons.) The longest day of the year in the northern or southern hemisphere occurs at the time in the orbit when points on the Tropic of Cancer or Tropic of Capricorn (23.45° north or south latitude) are pointed directly at the Sun at noon (so the Sun appears directly overhead). This time is known as the Summer Solstice in that hemisphere and the Winter Solstice in the opposite hemisphere. The times when the points on the equator are pointed directly at the Sun at noon are called the equinoxes, because at those times all points on Earth experience 12 hours between sunrise and sunset and 12 hours between sunset and sunrise.

title: Solar System/Earth


text:
Solar System/Moon

Size
The Moon's diameter is 3476 kilometers, or 0.2764 times that of Earth. This makes the Moon far larger relative to its planet than any other planetary moon in the solar system. In absolute terms it is the fifth largest planetary satellite in the solar system.

title: Solar System/Moon


text:
Solar System/Mars

Mars is the fourth planet from the Sun and the second smallest (after Mercury), with a diameter of 6794 km (53% of that of Earth). Mars is one of the four terrestrial planets (planets having a solid surface). If you were standing on Mars, you would weigh just 38% of what you weigh on Earth.

Orbit

Mars orbits the Sun once every 1.8809 Earth-years, with an orbital eccentricity of 0.093—the greatest eccentricity of any planet except Mercury. It averages 1.52 times as far from the Sun as does Earth.

Rotation
Mars rotates about its axis prograde (in the same direction as its solar orbit) once every 24 hours 37 minutes 23 seconds. This is closer to one Earth-day than the rotational period of any other planet. Its axis is tilted by 25.19° relative to the perpendicular of its orbital plane; this is closer to Earth's axial tilt of 23.45° than that of any other planet.

Atmosphere
Mars' atmosphere is made mostly of carbon dioxide (CO2). Its atmosphere is 0.6% the pressure of Earth's atmosphere.

Climate
The average temperature for Mars was -63 °C (-81 °F). Mars was once habitable until 3.5 billion years ago.

Internal structure
Scientists of 19th century believed that life had gained a toehold on Mars. Canals were discovered on the red planet by Italian astronomer, Giovanni Schiaparelli in 1887. These appeared as markings on the surface of Mars. Scientists believed that these canals are constructed by intelligent beings to divert water from polar regions to the desert areas. Like Earth, Mars had seasons. In spring and summer, the colour of the dark areas of the Mars changed from bluish green to yellow. So, it was suspected that plant life thrived on Mars. However, the Mars probe, Mariner 4 sent home pictures of a lifeless planet. Ultraviolet radiation from the sun coupled with the special nature of soil prevents Life from gaining on toehold on Mars.

Phobos

Phobos is the larger and closer of Mars's two satellites, with a diameter of just 26 km along one axis and just 18 km along another axis. Of all the moons that are their planet's largest, Phobos is the smallest both in absolute terms and relative to its planet's size.

Deimos
Deimos has a diameter of 16 km along one axis and 10 km along another.

Sojourner
Launched in 1997. It has a 2 MHz CPU and 64K of RAM. It has a camera capable of shooting photos up to 484p.

Spirit and Opportunity
Both launched in 2004. Both have 20 MHz RAD6000 CPUs, 128 MB of RAM and 256 MB storage. Both have cameras capable of shooting photos up to 1024p.

Curiosity
Launched in 2011 and landed in 2012. It is currently operating. It has 200 MHz PowerPC 750 CPU, 256 MB of RAM and 2 GB storage. It has cameras capable of shooting photos up to 1200p and video up to 720p@10.

Perserverance
Launched in 2020 and landed in 2021. It is currently operating. It has 200 MHz PowerPC 750 CPU, 256 MB of RAM and 2 GB storage. It has cameras capable of shooting photos up to 5K and video up to 720p@10.

title: Solar System/Mars


text:
Solar System/Jupiter

Jupiter is the fifth planet from the Sun. It is by far the largest planet, with a diameter of 142,984 kilometers (11.2 times that of Earth). Its mass is 317 times that of Earth. The volume of all the other planets combined is only 69% of Jupiter's volume; 1266 Earths would fit inside it. Jupiter is one of the four gas giants. If Jupiter had a solid surface and you stood on it, you would weigh 2.5 times what you weigh on Earth.

Physical characteristics
Jupiter is the giant planet of the Solar System, its diameter being eleven times greater than planet Earth's. Also, Jupiter's mass is over 300 times greater than Earth's. Jupiter rotates in less than ten hours, causing the middle of the planet to bulge out and the planet to flatten at its poles. This planet is a gas planet made up of hydrogen and helium, and what appears to be its surface is, in fact, the top of its atmosphere, which has swirls of other gases such as methane and ammonia.

Jupiter might be a giant planet, but it is not solid. Inside, it is made up mostly of liquid hydrogen. At the center lies a small core of rock and iron, which is believed to reach temperatures of at least 36,032 degrees Fahrenheit. Jupiter does not get much heat from the sun because it is so far away; this planet gives out its own heat. Heat rises from the center of Jupiter to the surface and passes into the atmosphere. The heat moves into belts of cooler gases which surround the planet.

Across Jupiter are dark bands, which change in darkness, size, and position from time to time. They are separated by lighter bands called zones. Like the wind patterns in Earth's atmosphere, the bands and zones on Jupiter are caused by heat. Also, Jupiter has a thin ring around it, like Saturn's but much smaller.

Rotation
Jupiter rotates prograde (in the same direction as it orbits) once every 9 hours 55.5 minutes, with its axis tilted just 3.13° from the perpendicular of its orbit.

Orbit
Jupiter orbits the Sun once every 11.86 Earth-years, at an average distance of 5.46 AU (Earth-Sun distances) and with an orbital eccentricity of .048.

The Great Red Spot
The Great Red Spot is a swirling storm hanging in Jupiter's atmosphere lying across two bands in the southern hemisphere. It is about 25,000 miles across- over three times the diameter of the Earth- and rotates counter clockwise with a period of around six days. The color is most likely due to phosphine brought up from lower layers, which is broken down by sunlight to create red sulfur.

Jupiter's Great Red Spot is approximately five miles higher than the clouds. The Pioneer and Voyager space probes found that the Great Red Spot is very cold which means that its top is very high in the atmosphere. At the spot's center, gas spirals up, raising pressure in a dome shape. The Great Red Spot is the largest storm in the solar system. It whips violently around Jupiter and has raged in the planet's atmosphere for more than 300 years.

The rings of Jupiter
The rings are very thin and dark unlike Saturn's rings that are thick and made of ice. Jupiter's rings are made of rock and other hard materials.

Satellites
Jupiter has 79 moons, which 53 have been named, and 61 are less than 10 km in diameter. Jupiter's sixteen largest moons divide into four groups. The four nearest Jupiter are tiny, next are the four large Galilean moons, much farther out are two clusters of four small, dark moons, and the farthest group of moons travels around Jupiter backwards compared to the other moons. The Galilean moons are named after an Italian astronomer, Galileo Galilei, who first spotted them in 1610.

Io
The inner two of the Galilean moons are Io and Europa, both of which are roughly the size of Earth's Moon. Io is a bright, red-orange world; it is covered with volcanoes. Clouds of sulfur and sulfur dioxide spew out of vents on Io's surface because the rock below the surface is hot and molten. Plumes rise up to 200 mi high. Io is home to the most energetic volcano in the solar system, Loki. Io is heated inside by constant twisting and turning due to the gravity of Jupiter, Europa, and Ganymede. The closeness to its planet is the reason for all its activity. The pull of the planet's gravity raises tides inside the moon, which produce heat and cause eruptions.

Europa
Europa is one of the two Galilean inner, large moons along with Io. Europa is covered by smooth ice. Jupiter's powerful gravity stirs Europa's icy crust and causes it to heat up; researchers believe there is liquid water below the moon's surface. This raises the question, "Could alien microbes have evolved in the waters of Europa?" Hydrothermal vents, like those on Earth's seafloor, may provide an energy source and create mineral-rich environments at the bottom of its ocean. Scientists are planning bold missions to this moon.

Ganymede
Ganymede is the largest planetary satellite in the solar system, and in fact its diameter is 8% larger than the planet Mercury's.

Callisto
Callisto is Jupiter's second largest moon and the third largest in the solar system. Its diameter is 98% of that of Mercury.

title: Solar System/Jupiter


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Cookbook:Asian-Inspired Chicken Salad

| Side dishes |  Asian Cuisine

This chicken salad is inspired by east and southeast Asian-associated flavors of soy, ginger, sesame, and mango.

Ingredients

 * 1½ cups broccoli flowerets
 * ½ cup pea pods
 * 6 cups torn mixed greens
 * 2 cups thinly-sliced Nappa cabbage
 * ½ cup julienned carrots
 * 1 package (6 oz) grilled chicken breast, cut in strips
 * ¾ cups salad dressing (teriyaki ginger, Asian sesame with ginger, or balsamic vinaigrette)
 * 1 mango, peeled, seeded, and thinly sliced (optional)
 * Sesame crackers (optional)

Procedure

 * 1) In large saucepan quickly plunge broccoli and pea pods into boiling water for 30 seconds. Drain vegetables. Quickly rinse with cold water. Drain well.
 * 2) In large bowl toss together the blanched broccoli and pea pods, greens, cabbage and carrots.
 * 3) Add chicken.
 * 4) Drizzle with salad dressing. Toss to coat.
 * 5) Arrange on 4 serving plates.
 * 6) Top with mango, if desired.
 * 7) Serve with crackers.

title: Cookbook:Asian-Inspired Chicken Salad


text:
Solar System/Saturn

Saturn is the sixth planet from the Sun and is the second largest planet (after Jupiter), with a diameter of 120536 kilometers (9.4 times that of Earth). Saturn is known for its spectacular rings, which can be clearly seen with a home telescope of modest size. Saturn is one of the four gas giants. Even though Saturn is much more massive than Earth, if it had a solid surface and you stood on it you would weigh only 6% more than you do on Earth. This is because you would be standing much farther from the center of the planet than you do on Earth.

Orbit
Saturn orbits the Sun in 29.46 Earth-years, with an orbital eccentricity of 0.05 and an average distance from the Sun of 9.54 AU (Earth-Sun distances).

Rotation
Saturn rotates prograde (in the direction of its path around the Sun) once every 10 hours 14 minutes, with an axial tilt of 25.33°.

Physical characteristics
Saturn is the only planet that is less dense than water—in fact its density is just 0.69 that of water.

Titan
Titan is the second largest moon in the solar system and has a diameter over 5% greater than that of the planet Mercury. It is the only planetary moon that has a thick atmosphere made of nitrogen. Titan has lakes made of liquid methane.

By 7.8 billion years in the future, when Sun will become a red giant star, Titan will become habitable.

title: Solar System/Saturn


text:
User talk:Psychofarm

Capitalization/Abbreviation

 * Regarding capitalisation and abbreviation, check out Cookbook:Policy. It seems that the norm on Cookbook is to capitalise as per "title case" e.g. Nappa Cabbage, rather than Nappa cabbage. Webaware 02:22, 17 November 2006 (UTC)

Firstly - as you didn't get one!
Hello and welcome to Wikibooks!

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You will find more resources in Community Portal. If you want to ask a question, visit the Study help desk, the Staff lounge, IRC channel or ask me personally on my talk page. For site news, see the Bulletin board. It might be an idea if you add this page to your "watchlist" so that you can see when any new information is posted there.

Good luck! -- Herby talk thyme 08:20, 12 December 2006 (UTC)

Wikibooks Newsletter, Volume 1
(Wikibooks gazette home | Discuss | Bulletin board | Subscription list)

This is a short newsletter that is being distributed to all active wikibookians. You are getting this message because you are recognized as an established contributor to the project. This newsletter will be distributed on a regular basis to help share news, information, and tips. It comes from a bot account, User:The Staff. User:The Staff is currently operated by a team of wikibooks admins, the complete list of which is available on the user page of the bot. If you would like to not receive this newletter anymore, please remove your name from the list at Active wikibookians.

The work you do at Wikibooks is greatly appreciated. However there are plenty of other opportunities for you to get involved and help us to create a thriving Wikibooks community. We are sure that there are things we can do to help you and your understanding of Wikibooks and similarly there are certainly things you could do to help Wikibooks become a better place.

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The Staff 04:17, 19 December 2006 (UTC)

Templates
Why are you duplicating Template:Infobox2 as Template:Psychofarm/Infobox and Template:Infobox Disease as Template:Psychofarm/Infobox Disease? -- Adrignola talk contribs 21:09, 6 September 2009 (UTC)

 * Template:Infobox Disease from Wikipedia uses Template:Infobox. The Wikibooks already has a Template:Infobox and it is not the same.  So I decided to recreate the Infobox and Infobox Disease Template but put my Username in front of them, rather than edit the Templates already in use.  Does this make sense?--Psychofarm (talk) 21:15, 6 September 2009 (UTC)

 * Now I see what you did to fix the problem. I will flag the ones I no longer need for speedy deletion.  I learned a lot through this little exercise, though.  Thanks for your help.--Psychofarm (talk) 21:20, 6 September 2009 (UTC)

 * To be honest, I made this mistake myself in the past as well. I should put a link to Template:Infobox2 on Template:Infobox to avoid confusion in the future.  Frankly, the infoboxes Template:Infobox were intended to create are not really used anymore by the books that used them.  I'd almost want to delete all the entries in Category:Infoboxes so that Template:Infobox2 can be moved to Template:Infobox to match up with the location Wikipedia has it at.  I don't know whose bright idea it was to create an alternate template at a conflicting name with a popular template on Wikipedia.  It was bound to cause problems in the future. -- Adrignola talk contribs 21:27, 6 September 2009 (UTC)

title: User talk:Psychofarm


text:
Transwiki talk:Bypassing the Great Firewall of China

Problems
But sometimes it does not work and occasionally, if a client try Tor to bypass the Great Fire Wall and employ Goolgle to search, then Goolgle, who may consider the client as a spyware or something, will refuse to perform the searching job.


text:
User:Psychofarm

Items to work on

 * /Sandbox
 * /Dopamine and BiPolar Disorder
 * /footnotes and references text
 * Cookbook:Collard Green needs recipe to be separated from item description page

My Contributions

 * Cookbook:Peach and Tomato Gazpacho
 * Cookbook:Green leaf detoxifier

Useful Internal Links

 * Cookbook:Policy
 * Recipe template

Personal psychiatry project

 * /asenapine
 * Template:Infobox Disease

title: User:Psychofarm


text:
Latin/Noun and Verb Tables

This reference is not nearly finished yet, but it will be soon (hopefully)!

title: Latin/Noun and Verb Tables


text: User:Newmanbe

title: User:Newmanbe


text:
Cookbook talk:Nappa Cabbage

Nappa - where?
Out of interest, where is this vegetable called "nappa cabbage" other than the USA? Koreans call it baechu, and it seems that most of China calls it wombok or something similar, or maybe also petsai. In Australia, it is usually called either wombok or Chinese cabbage. Where did this "nappa" name come from? Webaware 03:08, 17 November 2006 (UTC)
 * Originally, I presumed that it was a reference to Napa Valley, California, USA. This region of the country does in fact grow a lot of produce and grows it year round.  However, given it's use in Asian cooking it seemed doubtful the term would be used outside of the USA.  Interestingly, Nappa (Dragon Ball), is a fictional cartoon character in an anime, where the name is reported to be a pun on the cabbage.  This being the case and the difference in spelling of one 'p' vs two 'p', the Napa spelling might be a mispelling that is commonly used in the USA due to our connection to the Napa valley.  The Napa valley itself is not named after the cabbage but rather the word likely has native American origins.  Perhaps someone familiar with Asian culture might know if the Chinese call it Nappa?  I believe the petsai may be a name used in French countries or those Asian countries with histories of French colonization. Psychofarm 11:42, 17 November 2006 (UTC)

title: Cookbook talk:Nappa Cabbage


text:
User talk:ENGLISHTEACHER

l was teaching English Language in Nigeria before but now l will really like to be employed in any school in France,my email address is (ayoms710@yahoo.com) l shall satisfy you with my services if l could be employed. Thanks

title: User talk:ENGLISHTEACHER


text:
A-level Physics/Forces, Fields and Energy/Work and energy

Doing Work:

Work is done whenever a force moves something over a distance. The force moves through a distance, and we say that it does work. The amount of work done tells us the amount of energy that has been transferred by the force. Thus:

work done (J) = energy transferred (J)

To calculate the amount of work done W, we need to know two quantities:

- The magnitude of the force F. - The distance, d, moved by the force, in the direction of the force/parallel to the force.

So Work done $$W$$ = force $$F$$ × distance moved in the direction of the force $$x$$.
 * $$W = F x$$

or, where $$\Theta$$ is the angle between the direction of the force and the distance,
 * $$W = F x cos\Theta$$

Force is measured in $$newtons$$ and distance travelled parallel to the force in $$metres$$. Thus, Work done is described in newton metres or $$Nm$$. This is the SI unit, joule, $$J$$. work done by tension &= T \times D\\ work done against friction &= -F \times D\\ work done by gravity &= -mg \times h\\ \end{alignat}

Energy:

James Joule is the man, where the term 'the joule' comes from. His principle of conservation of energy states that:

While energy may be converted from one form to another, the total amount of energy in a closed system is always constant.

There are two main different types of energy; kinetic and potential. Kinetic energy (EK) is moving energy and potential energy (EP)is the energy that could be transferred to moving energy. The formula for these are:

Kinetic Energy: $$E_K = \frac{1}{2}mv^2$$

Potential Energy: $$E_P=mg\Delta h$$

The relationship between work done and energy is:

Work done = Energy transferred


text:
User talk:24.165.13.191

Welcome to Wikibooks. We invite everyone to contribute constructively to our collection. Take a look at the welcome page if you would like to learn more about contributing. However, unconstructive edits are considered vandalism, and if you continue in this manner you may be blocked from editing without further warning. Please stop, and consider improving rather than damaging the hard work of others. Thanks. -- Herby talk thyme 08:47, 17 November 2006 (UTC)

title: User talk:24.165.13.191


text:
Windows Registry Hacks

The Windows Registry is a database used by Microsoft Windows 95 and subsequent versions of Microsoft Windows that is used to store user preferences, setup, device, system configuration, etc. It is one of the least focused subjects in Windows operating system family. This book focusses on the various 'tweaks' that can be implemented using the Windows registry. For subjects like history of registry, structure of registry etc, please check Windows Registry.

Table of Contents

 * 1) Windows XP tweaks
 * 2) /Visual enhancement tweaks/
 * 3) /Common irritants/
 * 4) /Other miscellaneous tweaks/
 * 5) /Internet software tweaks/
 * 6) /Internet Explorer/
 * 7) /Outlook express/
 * 8) /Hardware Tweaks/
 * 9) /Network Related tweaks/
 * 10) /Security Related tweaks/
 * 11) /Software Removal/
 * 12) /HKEY_CLASSES_ROOT/
 * 13) /HKEY_CURRENT_CONFIG/
 * 14) /HKEY_CURRENT_USER/
 * 15) /HKEY_LOCAL_MACHINE/
 * 16) /HKEY_USERS/
 * 17) /Alphanumerical List of Microsoft Windows Registry Class Identifiers/
 * 18) /Alphanumerical List of Microsoft Windows Registry Type Library Entries/
 * 19) /Alphanumerical List of Microsoft Windows Registry Installer Component Entries/

title: Windows Registry Hacks


text:
Philippine History/The Philippine-American War

Introduction
The Philippine-American War, also called the Philippine Insurrection by the United States, was a war fought from 1899 to 1902 by forces of the First Philippine Republic (also called the Malolos Republic) under Gen. Emilio Aguinaldo (1898-1901) and Gen. Miguel Malvar (1901-1902) against the American forces under the command of Gen. Elwell Otis (1899-1900) and Gen. Arthur MacArthur (1900-1901). The immediate cause of the conflict was the fatal shooting of several Filipino soldiers over the San Juan Bridge by Pvt. William Grayson, an American soldier on February 4, 1899. It officially ended with the surrender of Gen. Miguel Malvar of the Philippine Republic in Batangas on April 16, 1902. However, there were generals who refused to recognize his order to surrender and sought to continue the war, considering themselves as spiritual heirs of the Katipunan. The most prominent of the latter group was led by Macario Sakay and his Republikang Tagalog. He was hanged for brigandage in 1907.

The Filipino-American War
When Intramuros was already completely surrounded by the U.S. naval and land troops, diplomatic negotiations were secretly conducted by Admiral Dewey and the Spanish governor-general through the Belgian consul. These negotiations led to the agreement of stating a mock battle to justify the turnover of Manila to the U.S. imperialists by the Spanish colonialists and were parallel to negotiations being held abroad towards the general settlement of the Spanish-American War through the mediation of the French government.

On August 13, 1898, the mock battle of Manila was staged by the U.S. imperialists and the Spanish colonialists. Aftepino revolutionary forces were conclusively deprived of the victory that was rightfully theirs. From then on, however, hatred of the U.S. imperialism became more widespread among the Filipino masses and their patriotic troops.

The Philippine revolutionary government shifted its headquarters from Cavite to Malolos, Bulacan in September in anticipation of further U.S. imperialist aggression. Here the Malolos Congress was held to put out a constitution that had for its models bourgeois-democratic constitutions. During the same period, the U.S. imperialists kept on insisting in diplomatic terms that Filipino troops withdraw further from where they had been pushed. The U.S. aggressors maneuvered to occupy more territory around Manila.

Attempts of the Aguinaldo government at diplomacy abroad to assert the sovereign rights of the Filipino people proved to be futile. On December 10, 1898, the Treaty of Paris was signed by the United States and Spain ceding the entire Philippines to the former at the price of $20 million and guaranteeing the property and business rights of Spanish citizens in the archipelago. On December 21, U.S. President McKinley issued the "Proclamation of Benevolent Assimilation" to declare in sugar-coated terms a war of aggression against the Filipino people.

On February 4, 1899, the U.S. troops made a surprise attack on the Filipino revolutionary forces in the vicinity of Manila. In the ensuing battles in the city, at least 3,000 Filipino were butchered while only 250 U.S. troops fell. Thus, armed hostilities between U.S. imperialism and the Filipino people began. The Filipino people heroically stood up to wage a revolutionary war of national liberation.

Before the Filipino-American War was decisively won by U.S. imperialism in 1902, 126,468 U.S. troops had been unleashed against the 7,000,000 Filipino people. These foreign aggressors suffered a casualty of at least 4,000 killed and almost 3,000 wounded. Close to 200,000 Filipino combatants and noncombatants were slain. In short, for every U.S. trooper killed, 50 Filipinos were in turn killed. More than a quarter of a million Filipinos died as a direct and indirect result of hostilities. However, an estimate of a U.S. general would even put the Filipino death casualty to as high as 600,000 or one-sixth of the population in Luzon then.

The U.S. imperialist aggressors practised genocide of monstrous proportions. They committed various forms of atrocities such as the massacres of captured troops and innocent civilians; pillage on women, homes and property; and ruthless employment of torture, such as dismemberment, the water cure and the rope torture. Zoning and concentration camps were resorted to in order to put civilians and combatants at their mercy.

As U.S. imperialism forced the Aguinaldo government to retreat, it played on the weaknesses in the ranks of the ilustrado leadership of the revolution. The imperialist chieftain McKinley dispatched the Schurman Commission in 1899 and then the Taft Commission in 1900 and issued to them instructions for the "pacification" of the country and cajolement of capitulationist traitors.

The liberal-bourgeois leadership of the old democratic revolution once more proved to be inadequate, flabby and compromising. Aguinaldo failed to lead the revolution effectively. He turned against such anti-imperialists as Mabini and Luna and increasingly relied on such capitulationists as Paterno and Buencamino. These two traitors who in previous years were notorious for their puppetry to Spanish colonialism had sneaked into the revolutionary government and usurped authority therein. They headed a pack of traitors who were deeply attracted to the siren song of "peace," "autonomy" and "benevolent assimilation" which the U.S. imperialists sang as they butchered the people.

In every town occupied by the U.S. imperialist troops, puppet municipal elections were held and dominated by the old principalia. These puppet elections excluded the masses who could not comply with the property and literacy requirements. These sham elections were used mainly to break off the principalia from the revolution and to attract its members into becoming running dogs in the same way that the Spanish colonialists had done.

As soon as traitors led by Paterno and Buencamino were in the hands of the U.S. imperialists, they were used to serve imperialist propaganda, chiefly to call on the people to lay down their arms. Under the instigation of the aggressors, particularly the U.S. army intelligence, Trinidad Pardo de Tavera organized the Partido Federal in 1900 to advocate the annexation of the Philippines by the United States. At the same time, the imperialists promulgated laws to punish those who would advocate independence.

The people and their revolutionary leaders who refused to take the oath of allegiance to the U.S. flag were persecuted, imprisoned or banished to Guam. Mass organizations, especially among the workers and peasants, were suppressed every time they surfaced.

In 1901, Aguinaldo himself was captured by the imperialists with the help of Filipino mercenaries. From then on, the treacherous counterrevolutionary forefathers of the Armed Forces of the Philippines were systematically organized and employed to help complete the imperialist conquest of the Filipino people. The first puppet constabularymen were used extensively in "mopping up" operations against persistent revolutionary fighters in Luzon and Visayas as well as in the subjugation of Mindanao.

Even when the main detachments of the Aguinaldo government had been defeated, armed resistance against U.S. imperialism still persisted in practically every town of the entire archipelago. The people of Bicol continued to wage armed struggle until 1903 when their leader Simeon Ola betrayed them by surrendering. In the Visayas, particularly Cebu, Samar, Leyte and Panay, the Pulahanes fought fierce battles against the U.S. aggressor troops and the puppet constabulary. So did the masses of Cavite, Batangas, Laguna and Quezon even after a general amnesty was issued. In Central Luzon, a religious organization, the Santa Iglesia, also waged armed resistance. In the Ilocos, associations that proclaimed themselves as the New Katipunan conducted a guerrilla war for national independence against U.S. imperialism. As late as 1907, puppet elections could not be held in Isabela because of the people's resistance. The most prominent of the final efforts to continue the revolutionary struggle in Luzon was led by Macario Sakay, from 1902 to 1906 in Bulacan, Pampanga, Laguna, Nueva Ecija and Rizal. It was only in 1911 that guerrilla war completely ceased in Luzon. However, the fiercest armed resistance after 1902 was waged by the people of Mindanao until as late as 1916.

For some time, U.S. imperialists succeeded in deceiving the Sultan of Sulu that his feudal sovereignty would be respected under the Bates Treaty of 1899 which he signed. When the foreign aggressors begun to put what they called the "Moro Province" under their administrative control, they had to contend with the Hassan uprising of 1903-1904; Usap rebellion of 1905; Pala revolt of 1905; Bud Dajo uprising of 1906; Bud Bagsak battle of 1913 and many others. This heroic resistance of the people was quelled with extreme atrocity.

The Sedition Law of 1901, the Brigandage Act of 1902 and the Reconcentration Act of 1903 were passed by U.S. imperialism to sanction military operations against the people as mere police operations against "common criminals." Patriots were called bandits. People in extensive areas were herded into military camps in order to separate them from the patriotic guerrillas.

The war expenditures of U.S. imperialism in the conquest of the Philippines were paid for by the Filipino people themselves. They were compelled to pay taxes to the U.S. colonial regime to defray a major part of the expenditures and the interest on bonds floated in the name of the Philippine government through the Wall Street banking houses. Of course, the superprofits derived from the protracted exploitation of the Filipino people would constitute the basic gains of U.S. imperialism.


text:
High School Mathematics Extensions/Primes/text

Introduction
A prime number (or prime for short) is a natural number that has exactly two divisors: itself and the number 1. Since 1 has only one divisor — itself — we do not consider it to be a prime number but a unit. So, 2 is the first prime, 3 is the next prime, but 4 is not a prime because 4 divided by 2 equals 2 without a remainder. We've proved 4 has three divisors: 1, 2, and 4. Numbers with more than two divisors are called composite numbers.

The first 20 primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, and 71.

Primes are an endless source of fascination for mathematicians. Some of the problems concerning primes are so difficult that even decades of work by some of the most brilliant mathematicians have failed to solve them. One such problem is Goldbach's conjecture, which proposes that all even numbers greater than 3 can be expressed as the sum of two primes. No one has been able to prove it true or false.

This chapter will introduce some of the elementary properties of primes and their connection to an area of mathematics called modular arithmetic.

Geometric meaning of primes
Given 12 pieces of square floor tiles, can we assemble them into a rectangular shape in more than one way? Of course we can, this is due to the fact that

\begin{matrix} 12 &=& 12 \times 1 \\ &=& 6 \times 2\\ &=& 4 \times 3\\ \end{matrix} $$ We do not distinguish between 2×6 and 6×2 because they are essentially equivalent arrangements.

But what about the number 7? Can you arrange 7 square floor tiles into rectangular shapes in more than one way? The answer is no, because 7 is a prime number.

Fundamental Theorem of Arithmetic
A theorem is a non-obvious mathematical fact. A theorem must be proven; a proposition that is generally believed to be true, but without a proof, is called a conjecture or a hypothesis.

With those definitions out of the way the fundamental theorem of arithmetic simply states that:
 * Any natural number (except for 1) can be expressed as the product of primes in one and only one way.

For example
 * $$12 = 2 \times 2 \times 3 \,\!$$

Rearranging the multiplication order is not considered a different representation of the number, so there is no other way of expressing 12 as the product of primes.

A few more examples

\begin{matrix} 99 &=& 3 &\times &3 &\times &11 \\ 52 &=& 2 &\times &2 &\times &13 \\ 17 &=& 17 & \end{matrix} $$

It can be easily seen that a composite number has more than one prime factor (counting recurring prime factors multiple times).

Why?

Bearing in mind the definition of the fundamental theorem of arithmetic, why isn't the number 1 considered a prime?

Factorization
We know from the fundamental theorem of arithmetic that any integer can be expressed as the product of primes. The million dollar question is: given a number x, is there an easy way to find all prime factors of x?

If x is a small number then it is easy. For example 90 = 2 × 3 × 3 × 5. But what if x is large? For example x = 4539? Most people can't factorize 4539 into primes in their heads. But can a computer do it? Yes, the computer can factorize 4539 fairly quickly. We have 4539 = 3 × 17 × 89.

Since computers are very good at doing arithmetic, we can work out all the factors of x by simply instructing the computer to divide x by 2 then 3 then 5 then 7 ... and so on.

So there is an easy way to factorize a number into prime factors. Just apply the method described above. However, that method is too slow for large numbers: trying to factorize a number with thousands of digits would take more time than the current age of the universe. But is there a fast way? Or more precisely, is there an efficient way? There may be, but no one has found one yet. Some of the most widely used encryption schemes today (such as RSA) make use of the fact that we can't factorize large numbers into prime factors quickly. If such a method is found, a lot of internet transactions will be rendered unsafe.

Consider the following three examples of the dividing method in action.

Example 1
 * $$x = 21$$

 * $$\frac{x}{2} = 10.5$$ not a whole number, so 2 is not a factor of 21

 * $$\frac{x}{3} = 7$$ hence 3 and 7 are the factors of 21.

Example 2

 * $$x=153$$

 * $$\frac{x}{2} =76.5$$ hence 2 is not a factor of 153

 * $$\frac{x}{3} =51$$ hence 3 and 51 are factors of 153

 * $$\frac{51}{3} =17$$ hence 3 and 17 are factors of 153

It is clear that 3, 9, 17 and 51 are the factors of 153. The prime factors of 153 are 3, 3 and 17 (3×3×17 = 153)

Example 3

 * $$\frac{2057}{2}=1028.5$$

 * $$\cdots$$

 * $$\frac{2057}{11}=187$$

 * $$\frac{187}{11}=17$$

 * hence 11, 11 and 17 are the prime factors of 2057.

Exercise
 {Factorise the given numbers below}

{ 13={ 13|prime (i) _25 }
 * type="{}"}

{ 26={ 2*13|13*2|2 * 13|13 * 2|2×13|13×2|2 × 13|13 × 2|2X13 (i)|13X2 (i)|2 X 13 (i)|13 X 2 (i) _25 }
 * type="{}"}

{ 59={ 59|prime (i) _25 }
 * type="{}"}

{ 82={ 2*41|41*2|2 * 41|41 * 2|2×41|41×2|2 × 41|41 × 2|2X41 (i)|41X2 (i)|2 X 41 (i)|41 X 2 (i) _25 }
 * type="{}"}

{ 101={ 101|prime (i) _25 }
 * type="{}"}

{ 121={ 11^2|11*11|11 * 11|11×11|11 × 11|11X11 (i)|11 X 11 (i) _25 }
 * type="{}"}

{Give up if it takes too long. There is a quick way. 2187={ 3^7|3*3*3*3*3*3*3|3 * 3 * 3 * 3 * 3 * 3 * 3|3×3×3×3×3×3×3|3 × 3 × 3 × 3 × 3 × 3 × 3|3X3X3X3X3X3X3 (i)|3 X 3 X 3 X 3 X 3 X 3 X 3 (i) _25 }
 * type="{}" coef="2"}

Fun Fact — Is this prime?
 Interestingly, there is an efficient way of determining whether a number is prime with 100% accuracy with the help of a computer.

2, 5 and 3
The primes 2, 5, and 3 hold a special place in factorization. Firstly, all even numbers have 2 as one of their prime factors. Secondly, all numbers whose last digit is 0 or 5 can be divided wholly by 5.

The third case, where 3 is a prime factor, is the focus of this section. The underlying question is: is there a simple way to decide whether a number has 3 as one of its prime factors?

Theorem — Divisibility by 3
 A number is divisible by 3 if and only if the sum of its digits is divisible by 3

For example, 272 is not divisible by 3, because 2 + 7 + 2 = 11, which is not divisible by 3.

945 is divisible by 3, because 9 + 4 + 5 = 18. And 18 is divisible by 3. In fact 945 / 3 = 315

Is 123456789 divisible by 3?

 * 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = (1 + 9) × 9 / 2 = 45

 * 4 + 5 = 9

Nine is divisible by 3, therefore 45 is divisible by 3, therefore 123456789 is divisible by 3!

The beauty of the theorem lies in its recursive nature. A number is divisible by 3 if and only if the sum of its digits is divisible by 3. How do we know whether the sum of its digits is divisible by 3? Apply the theorem again!

info — Recursion
 A prominent computer scientist once said "To iterate is human, to recurse, divine." But what does it mean to recurse? Before that, what is to iterate? "To iterate" simply means doing the same thing over and over again, and computers are very good at that. An example of iteration in mathematics is the exponential operation, e.g. xn means doing x times x times x times x...n times. That is an example of iteration.

Thinking about iteration economically (in terms of mental resources), by defining a problem in terms of itself, is "to recurse". To recursively represent xn, we write:

x^n = 1 $$ if n equals 0.

x^n = x\times x^{n-1} $$ if n > 0 What is 99? It is 9 times 9 8. But, 98 is 9 times 97. Repeating this way is an example of recursion.

Exercises
 {For questions 1-3, factorize:}

{ 45={ 3^2*5|5*3^2|3^2 * 5|5 * 3^2|3^2×5|5×3^2|3^2 × 5|5 × 3^2|3^2X5 (i)|5X3^2 (i)|3^2 X 5 (i)|5 X 3^2 (i)|3*3*5|5*3*3|3 * 3 * 5|5 * 3 * 3|3×3×5|5×3×3|3 × 3 × 5|5 × 3 × 3|3X3X5 (i)|5X3X3 (i)|3 X 3 X 5 (i)|5 X 3 X 3 (i) _25 }
 * type="{}"}

{ 4050={ 2*3^4*5^2|5^2*3^4*2|2 * 3^4 * 5^2|5^2 * 3^4 * 2|2×3^4×5^2|5^2×3^4×2|2 × 3^4 × 5^2|5^2 × 3^4 × 2|2X3^4X5^2 (i)|5^2X3^4X2 (i)|2 X 3^4 X 5^2 (i)|5^2 X 3^4 X 2 (i)|2*3*3*3*3*5*5|5*5*3*3*3*3*2|2 * 3 * 3 * 3 * 3 * 5 * 5|5 * 5 * 3 * 3 * 3 * 3 * 2|2×3×3×3×3×5×5|5×5×3×3×3×3×2|2 × 3 × 3 × 3 × 3 × 5 × 5|5 × 5 × 3 × 3 × 3 × 3 × 2|2X3X3X3X3X5X5 (i)|5X5X3X3X3X3X2 (i)|2 X 3 X 3 X 3 X 3 X 5 X 5 (i)|5 X 5 X 3 X 3 X 3 X 3 X 2 (i) _25 }
 * type="{}"}

{ 2187={ 3^7|3*3*3*3*3*3*3|3 * 3 * 3 * 3 * 3 * 3 * 3|3×3×3×3×3×3×3|3 × 3 × 3 × 3 × 3 × 3 × 3|3X3X3X3X3X3X3 (i)|3 X 3 X 3 X 3 X 3 X 3 X 3 (i) _25 }
 * type="{}"}

{Show that the divisible-by-3 theorem works for any 3 digit number. (do it on paper)
 * type="{}" coef="3"}
 * Hint: Express a 3 digit number as 100a + 10b + c, where 0 ≤ a, b and c ≤ 9 Solution

{A number is divisible by 9 if and only if the sum of its digits is divisible by 9. +True -False
 * type=""}

{Determine whether the numbers for questions 6-9 are divisible by 9.}

{89 -Yes +No
 * type=""}

{558 +Yes -No
 * type=""}

{51858 +Yes -No
 * type=""}

{41857 -Yes +No
 * type=""}

Finding primes
The prime sieve is a relatively efficient method for finding all primes less than or equal to a specified number. To find all primes less than or equal to 50, we do the following:

First, we write out the numbers 1 to 50 in a table as below

\begin{matrix} 1 & 2 &  3 &  4 &  5 &  6 &  7 &  8 &  9 & 10 \\ 11 & 12 & 13 & 14 & 15 & 16 & 17 & 18 & 19 & 20 \\ 21 & 22 & 23 & 24 & 25 & 26 & 27 & 28 & 29 & 30 \\ 31 & 32 & 33 & 34 & 35 & 36 & 37 & 38 & 39 & 40 \\ 41 & 42 & 43 & 44 & 45 & 46 & 47 & 48 & 49 & 50 \\ \end{matrix} $$

Cross out 1, because it's not a prime.

\begin{matrix} X & 2 &  3 &  4 &  5 &  6 &  7 &  8 &  9 & 10 \\ 11 & 12 & 13 & 14 & 15 & 16 & 17 & 18 & 19 & 20 \\ 21 & 22 & 23 & 24 & 25 & 26 & 27 & 28 & 29 & 30 \\ 31 & 32 & 33 & 34 & 35 & 36 & 37 & 38 & 39 & 40 \\ 41 & 42 & 43 & 44 & 45 & 46 & 47 & 48 & 49 & 50 \\ \end{matrix} $$

Now 2 is the smallest number not crossed out in the table. We mark 2 as a prime and cross out all multiples of 2 i.e. 4, 6, 8, 10 ...

\begin{matrix} X & 2_p & 3 & X &  5 & X &  7 & X &  9 & X \\ 11 &  X & 13 & X & 15 & X & 17 & X & 19 & X \\ 21 &  X & 23 & X & 25 & X & 27 & X & 29 & X \\ 31 &  X & 33 & X & 35 & X & 37 & X & 39 & X \\ 41 &  X & 43 & X & 45 & X & 47 & X & 49 & X \\ \end{matrix} $$

Now 3 is the smallest number not marked in anyway. We mark 3 as a prime and cross out all multiples of 3 i.e. 6, 9, 12, 15 ...

\begin{matrix} X & 2_p & 3_p & X & 5 & X &  7 & X &  X & X \\ 11 &  X &  13 & X &  X & X & 17 & X & 19 & X \\ X &  X &  23 & X & 25 & X &  X & X & 29 & X \\ 31 &  X &   X & X & 35 & X & 37 & X &  X & X \\ 41 &  X &  43 & X &  X & X & 47 & X & 49 & X \\ \end{matrix} $$

Continue this way to find all the primes. When do you know you have found all the primes under 50? Note that this algorithm is called Sieve of Eratosthenes

Exercise

\begin{matrix} X & 2 & 3 & X & 5 &X &7& X& X& X \\ 11 & X & 13 & X& X& X&17 &X& 19& X\\ X& X& 23 & X& X &X&X&X&29& X\\ 31 &X& X& X& X &X&37& X& X& X\\ 41 & X& 43 & X& X&X&47& X& X& X\\ \end{matrix} $$The prime sieve has been applied to the table above. Notice that every number situated directly below 2 and 5 are crossed out. Construct a rectangular grid of numbers running from 1 to 60 so that after the prime sieve has been performed on it, all numbers situated directly below 2 and 5 are crossed out. What is the width of the grid?
 * Find all primes below 200.
 * Find the numbers which are divisible by 3 below 200. Did you change the width of your grid?

Infinitely many primes
To answer the question ''what is the largest prime number?  let us first answer what is the largest natural number?'' If somebody tells you that $$10^{10}$$ is the largest natural number, you can immediately prove them wrong by telling them that $$10^{10} + 1$$ is a larger natural number. You can substitute $$10^{10}$$ with any number other natural number $$n$$ and your argument will still work. This means that there is no such thing as the largest natural number. (Some of you might be tempted to say that infinity is the largest natural number. However, infinity is not a natural number but just a mathematical concept.)

The ancient Greek mathematician Euclid, had the following proof of the infinitude of primes.

Proof of infinitude of primes
Let us first assume that
 * there are a finite number of primes

therefore
 * there must be one prime that is greater than all others,

let this prime be referred to as n. We now proceed to show the two assumptions made above will lead to a contradiction, and thus there are infinitely many primes.

Take the product of all prime numbers to yield a number x. Thus:
 * $$x = 2 \times 3 \times 5 \times \ldots \times n \!$$

Then, let y equal one more than x:
 * $$y = x + 1 \!$$

One may now conclude that y is not divisible by any of the primes up to n, since y differs from a multiple of each such prime by exactly 1. Since y is not divisible by any prime number, y must either be prime, or its prime factors must all be greater than n, a contradiction of the original assumption that n is the largest prime! Therefore, one must declare the original assumption incorrect, and that there exists an infinite number of primes.

 Fun Fact — Largest known prime   The largest known prime is 282,589,933-1. It has a whopping 24,862,048 digits! Primes of the form 2n-1 are called Mersenne primes named after the French monk/amateur mathematician.

Useful Off-site Resources

 * "The Prime Pages. Prime Number Research, Records, and Resources"


text:
User talk:68.33.208.134

Welcome!
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title: User talk:68.33.208.134


text:
Animal Care/House Gecko

The Tropical House Gecko (scientific name Hemidactylus frenatus), is a native of southeastern Asia and the northern parts of Africa. Known as the Pacific house gecko, it is the most recently discovered member of a quartet of small, prolific and aggressive little lizards that become active at twilight. They can be seen climbing walls of houses and other buildings in search of insects attracted to porch lights, hence their name. Spread around the world by ships, these geckos are now common around Florida and other southern areas of the United States.

A tropical gecko, Hemidactylus Frenatus likes to live in warm, humid areas where it can crawl around on rotting wood in search of the insects it eats. Keep this in mind if you attempt to recreate its habitat should you decide to keep one as a pet.

House geckos are fast moving so catching them may be difficult. Be careful when handling them as their tails detach easily as a defence mechanism.

These small geckos grow to three to six inches in length and live about five years.

House Geckos in Captivity
Easy to care for, all you need is a vivarium which can be a ten gallon or larger fish tank, clean substrate [store bought] a secure cover for the tank, a heat source [such as an incandescent light bulb with reflector], some branches for your gecko to climb on, a rock for him/her to bask on, and some plants to collect droplets of water from your misting bottle as these geckos usually won't drink from a dish.

Choose a gecko from a reputable dealer. Make sure he/she looks healthy: a healthy gecko will have clear eyes nose and anus, be alert and active, have good looking skin and have a good appetite and be well fleshed out. Sick geckos may appear thin, have poor looking skin, discharge from the nose, eyes or anus, and appear lethargic. Some stores sell house geckos as snake food, so be aware of poorly treated geckos meant to be served as dinner.

If you want more than one gecko, do not house more than one male per tank as they will fight each other, and make sure you have all females unless you want to breed them.

Clean out your tank with a mild [3%] solution of water and chlorine bleach, then rinse until all odor of chlorine is gone. Besides daily removal of feces, be sure to clean the tank when it gets dirty [once a week to once a month].

Layer the bottom of the tank with a clean, non-toxic substrate such as coconut hair [available at your pet store], non-toxic wood shavings [avoid cedar), carpet (bought from a pet store) or ordinary potting soil.

Place a clean branch, a rock or two, and perhaps a piece of tree bark in the tank. Geckos love to hide on the underside of branches or chunks of bark during the day while they sleep. They also love to climb on rocks to bask as well as enjoy the stored heat.

If you wish, put in some small potted plants and keep them well watered. This will aid in keeping the humidity high in the tank as well as provide a more natural setting for your gecko. Using potted plants makes it easier to remove them for your frequent tank cleaning.

Put your light/heat source on one end of the tank so as to make a temperature gradient from one end of the tank to the other.If you don't have any heat souce, every day just put a rock in the sun for one hour and then place it in the tank, this will create a none harmful heat souce that lasts four to five hours.. Ordinary light bulbs in metal reflectors from a hardware store, placed on top of a metal screen lid, make excellent heat sources and provide a 'day' period that allow the gecko to sleep. Other heat sources that work well are ceramic heaters. Under tank heaters can also be used and can help maintain a minimum temperature.

Daytime temperatures of the vivarium should be around 29-32 °C (85-90 °F) on the hot side and 21-24 °C (70-75 °F) on the cool side during the day and 21-24 °C (70-65 °F) at night. Note: do NOT use an electric heater rock sold by some pet stores. They can malfunction and more than one gecko has died from excess heat created by these devices.

Try to keep the humidity in the tank around 75% by liberal spraying with de-chlorinated water from a spray bottle, well watered house plants or perhaps a humidor made of moss, wood chips, or coconut hair soaked in water and placed in a container on the opposite side of the tank from the heat source.

Since they are carnivorous you need to provide live insects for food, although when you fist capture or buy them they might not eat for two or three days (due to stress). Either crickets and mealworms purchased at a pet store or live bugs caught around the house. Choose crickets that are smaller than your gecko's head. Too large of a cricket can actually bite and wound a gecko.

It is best to supplement crickets and mealworms by dusting them with a calcium/vitamin powder available from your pet store. Feeding your gecko insects caught in the wild will help provide a more balanced diet as their guts will contain many varied nutrients that farm raised crickets will not. Feed just before evening every other day.

Be careful when handling your gecko because they have both a very delicate skin that can be easily torn and a detachable tail that contains a large proportion of the animal's fat stores.These geckos are also pretty fast so make sure to be gentle.Losing a tail isn't too traumatic, but repeatedly losing a tail can weaken a gecko as they use a great deal of energy to replenish the lost tail and its fat store.

Be sure to wash your hands well after handling your gecko or any part of its habitat to avoid salmonella. Wearing disposable gloves can minimize disease transmission.

title: Animal Care/House Gecko


text:
User:Hst99999~enwikibooks

testing by me

title: User:Hst99999~enwikibooks


text:
User talk:Varun kumar

Hello and welcome to Wikibooks!

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You will find more resources in Community Portal. If you want to ask a question, visit the Study help desk, the Staff lounge, IRC channel or ask me personally on my talk page.

Good luck! -- Herby talk thyme 12:44, 17 November 2006 (UTC)

Reg hacking
This interests me in a number of senses. If I can help do say. Also look around some pages may be worth linking to etc etc Securing Windows XP for instance? Regards -- Herby talk thyme 18:07, 7 January 2007 (UTC)

title: User talk:Varun kumar


text:
User talk:Varun Kumar

Let's do it properly!

Hello and welcome to Wikibooks!

Here are some tips to help you get started:
 * You can sign your name on Talk and vote pages using four tildes, like this: ~~~~.
 * Remember to conduct any editing experiments in the sandbox.
 * If you're a Wikipedian, see Wikibooks for Wikipedians for a primer on how things work here (it's a little different).
 * If you want to base your work here on materials from Wikipedia, please use WB:RFI to bring the material over in compliance with the GFDL.
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 * Please say hello at the Staff Lounge with any questions or ideas.
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You will find more resources in Community Portal. If you want to ask a question, visit the Study help desk, the Staff lounge, IRC channel or ask me personally on my talk page.

Good luck! -- Herby talk thyme 13:14, 17 November 2006 (UTC)

Portal, WP & WB
Hi

I guess the first thing is that that things are not the same here as WP. Hard to really put into words but stick around and you will see. There are considerably less contributors so less active pages to "chat" on such as WP portals. Look around - talk pages on Computer science bookshelf, All bookshelves or Community Portal may help however the staff lounge gets as much traffic as anywhere else. All the best -- Herby talk thyme 13:18, 17 November 2006 (UTC)

Template:Registry
I was just wondering if this template should rather have a different, possibly more descriptive, name.

Also, it could use a "usage" section. I'm of the school of creating sub-pages for usage. That way, the template and usage section histories aren't mixed and usage sections of protected pages can still be edited. To prevent the usage section from being displayed, use the tag (the  is also an interesting one). --Swift 18:08, 31 December 2006 (UTC)

title: User talk:Varun Kumar


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User talk:Ekel dumaop1989

Thanks for experimenting with Wikibooks. Your test worked, and has now been removed. Please use Sandbox for any other tests you want to do, since testing material in modules will normally be removed quickly. Please see the welcome page if you would like to learn more about contributing to our project. Thanks. -- Herby talk thyme 13:19, 17 November 2006 (UTC)

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A-level Chemistry/AQA/Module 1/Bonding

Intermolecular Forces
The bonds which act between a molecules are called intermolecular forces. The word intermolecular means, "between molecules". There are three kinds of intermolecular forces.

Van Der Waals
Temporary Induced Dipole-Dipole Attractions Also known as London forces. These are the weakest of the intermolecular forces.

Dipole-Dipole
Also known as Dispersion forces.

Hydrogen Bonding
This is the strongest type of intermolecular force. This only occurs between a lone pair of electrons on a Nitrogen (N), Oxygen (O) or Fluorine (F)atom and a hydrogen atom that has a strong partial charge(δ+). The electronegative atom pulls electrons away from the hydrogen so that, on the opposite side to the bond, the hydrogen appears almost like an unshielded proton.

Ionic
This occurs between oppositely charged ions (atoms or molecules which have gained or lost electrons). An example of an ionically bonded compound is NaCl.

The sodium exists as a positive ion, $$Na^+$$ (positively charged). It loses the electron in its $$3s^1$$ sub-energy level, giving it a stable electron configuration of $$1s^22s^22p^6$$, or $$[Ne]$$. This electron is donated into the 2p sub-energy level of the chlorine atom, which then forms a chloride ion, $$Cl^-$$. This also now has a stable electron configuration of $$1s^22s^22p^6$$.

The force of attraction (called the "electrostatic force of attraction") between these two ions, caused by their opposite charges, is the ionic bond.

The ions arrange themselves into "giant ionic lattices", which are regular, repeating structures. Ionic compounds are usually white and crystalline in appearance; they have high melting and boiling points, as a lot of energy is required to overcome the electrostatic forces of attraction. They can, however, be disrupted by polar solvents, such as water; they are, therefore, water soluble.

Covalent
The term covalent bond is used to describe the bonds in compounds that result from the sharing of one or more pairs of electrons. This is usually indicated as H-F. The electron pair creates a 'bond' between the two atoms because it attracts the nucleus of each atom and therefore resist the separation of the two atoms.

A co-ordinate bond (also called a dative covalent bond) is a covalent bond (a shared pair of electrons) in which both electrons come from the same atom.

Metallic
Positive ions are arranged in a lattice with a sea of delocalised (free) electrons. The force of attraction between the delocalised electrons and positively charged ions holds the structure together.

title: A-level Chemistry/AQA/Module 1/Bonding


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title: User talk:168.9.35.14