Solar energy the next generation power

Solar energy is radiant light and heat from the sun harnessed using a range of ever-evolving technologies solar heating, solar photovoltaics, solar thermal electricity, solar architecture and artificial photosynthesis.

such as

Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.

In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating climate change, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared".

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How Can science prove the age of the earth?

No scientific method can prove the age of the earth and the universe, and that includes the ones we have

listed here. Although age indicators are called ‘clocks’ they aren’t, because all ages result from calculations that necessarily involve making assumptions about the past. Always the starting time of the ‘clock’ has to be assumed as well as the way in which the speed of the clock has varied over time. Further, it has to be assumed that the clock was never disturbed.

There is no independent natural clock against which those assumptions can be tested. For example, the amount of cratering on the moon, based on currently observed cratering rates, would suggest that the moon is quite old. However, to draw this conclusion we have to assume that the rate of cratering has been the same in the past as it is now. And there are now good reasons for thinking that it might have been quite intense in the past, in which case the craters do not indicate an old age at all (see below).

Ages of millions of years are all calculated by assuming the rates of change of processes in the past were the same as we observe today—called the principle of uniformitarianism. If the age calculated from such assumptions disagrees with what they think the age should be, they conclude that their assumptions did not apply in this case, and adjust them accordingly. If the calculated result gives an acceptable age, the investigators publish it.

Examples of young ages listed here are also obtained by applying the same principle of uniformitarianism. Long-age proponents will dismiss this sort of evidence for a young age of the earth by arguing that the assumptions about the past do not apply in these cases. In other words, age is not really a matter of scientific observation but an argument about our assumptions about the unobserved past.

The assumptions behind the evidences presented here cannot be proved, but the fact that such a wide range of different phenomena all suggest much younger ages than are currently generally accepted, provides a strong case for questioning those accepted ages (13.77 billion years for the universe and 4.54 billion years for the solar system).

Also, a number of the evidences, rather than giving any estimate of age, challenge the assumption of slow-and-gradual uniformitarianism, upon which all deep-time dating methods depend. 

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Galaxy Collision (Video)

Two spiral galaxies undergo a protracted crash lasting two billion years, eventually merging into a single
elliptical galaxy. Credit: NCSA/NASA/B. Robertson (Caltech) and L. Hernquist (Harvard Univ.)

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The stars of the space

A star is a massive, luminous sphere of plasma held together by its own gravity. The nearest star to Earth is Sun, which is the source of most of the planet's energy. Some other stars are visible from Earth during the night, appearing as a multitude of fixed luminous points due to their immense distance. Historically, the most prominent stars were grouped into constellations and asterisms, and the brightest stars gained proper names. Extensive catalogues of stars have been assembled by astronomers, which provide standardized star designations.

the

For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space. Once the hydrogen in the core of a star is nearly exhausted, almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star's lifetime and, for some stars, by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, luminosity, and spectrum respectively. The total mass of a star is the principal determinant of its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star's environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities, known as a Hertzsprung–Russell diagram (H–R diagram), allows the age and evolutionary state of a star to be determined.

A star's life begins with the gravitational collapse of a gaseous nebula of material composed primarily of^[1] The remainder of the star's interior carries energy away from the core through a combination of radiative and convective processes. The star's internal pressure prevents it from collapsing further under its own gravity. Once the hydrogen fuel at the core is exhausted, a star with at least 0.4 times the mass of the Sun^[2] expands to become a red giant, in some cases fusing heavier elements at the core or in shells around the core. The star then evolves into a degenerate form, recycling a portion of its matter into the interstellar environment, where it will contribute to the formation of a new generation of stars with a higher proportion of heavy elements.^[3] Meanwhile, the core becomes a stellar remnant: a white dwarf, a neutron star, or (if it is sufficiently massive) a black hole.

hydrogen, along with helium and trace amounts of heavier elements. Once the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process.

Binary and multi-star systems consist of two or more stars that are gravitationally bound, and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution.^[4] Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy.

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NASA’s Chandra X-ray Observatory Finds Planet That Makes Star Act Deceptively Old

A planet may be causing the star it orbits to act much older than it actually is, according to new data from Chandra X-ray Observatory. This discovery shows how a massive planet can affect the behavior of its parent star.
NASA’s
The star, WASP-18, and its planet, WASP-18b, are located about 330 light-years from Earth. WASP-18b has a mass about 10 times that of Jupiter and completes one orbit around its star in less than 23 hours, placing WASP-18b in the “hot Jupiter” category of exoplanets, or planets outside our solar system.
WASP-18b is the first known example of an orbiting planet that has apparently caused its star, which is roughly the mass of our sun, to display traits of an older star.
“WASP-18b is an extreme exoplanet,” said Ignazio Pillitteri of the Istituto Nazionale di Astrofisica (INAF)-Osservatorio Astronomico di Palermo in Italy, who led the study. “It is one of the most massive hot Jupiters known and one of the closest to its host star, and these characteristics lead to unexpected behavior. This planet is causing its host star to act old before its time.”
Pillitteri’s team determined WASP-18 is between 500 million and 2 billion years old, based on theoretical models and other data. While this may sound old, it is considered young by astronomical standards. By comparison, our sun is about 5 billion years old and thought to be about halfway through its lifetime.
Younger stars tend to be more active, exhibiting stronger magnetic fields, larger flares, and more intense X-ray emission than their older counterparts. Magnetic activity, flaring, and X-ray emission are linked to the star’s rotation, which generally declines with age. However, when astronomers took a long look with Chandra at WASP-18 they didn’t detect any X-rays. Using established relations between the magnetic activity and X-ray emission of stars, as well as its actual age, researchers determined WASP-18 is about 100 times less active than it should be.
“We think the planet is aging the star by wreaking havoc on its innards,” said co-author Scott Wolk of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
The researchers argue that tidal forces created by the gravitational pull of the massive planet – similar to those the moon has on Earth’s tides, but on a much larger scale – may have disrupted the magnetic field of the star.
The strength of the magnetic field depends on the amount of convection in the star, or how intensely hot gas stirs the interior of the star.

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Pluto the 9th planet solar system

Pluto (minor-planet designation 134340 Pluto) is the largest object in the Kuiper belt, and the tenth-Sun. It is the second-most-massive known dwarf planet, after Eris. Like other Kuiper-belt objects, Pluto is composed primarily of rock and ice^[15] and is relatively small, approximately one-sixth the mass of the Moon and one-third its volume. It has an eccentric and highly inclined orbit that takes it from 30 to 49 AU (4.4–7.4 billion km) from the Sun. This causes Pluto to periodically come closer to the Sun than Neptune, but an orbital resonance with Neptune prevents the bodies from colliding. In 2014 it was 32.6 AU from the Sun.

most-massive body observed directly orbiting the

Discovered in 1930, Pluto was originally classified as the ninth planet from the Sun. Its status as a major planet fell into question following further study of it and the outer Solar System over the ensuing 75 years. Starting in 1977 with the discovery of the minor planet 2060 Chiron, numerous icy objects similar to Pluto with eccentric orbits were found.^[16] The most notable of these was the scattered disc object Eris, discovered in 2005, which is 27% more massive than Pluto. The understanding that Pluto is only one of several large icy bodies in the outer Solar System prompted the International Astronomical Union (IAU) to define formally in 2006 what it means to be a "planet". This definition excluded Pluto and reclassified it as a member of the new "dwarf planet" category (and specifically as a plutoid).^[18] Astronomers who oppose this decision hold that Pluto should have remained classified as a planet, and that other dwarf planets and even moons should be added to the roster of planets along with Pluto.

Pluto has five known moons: Charon (the largest, with a diameter just over half that of Pluto), Nix, Hydra, Kerberos, and Styx. Pluto and Charon are sometimes described as a binary system because the barycenter of their orbits does not lie within either body.^[23] The IAU has yet to formalise a definition for binary dwarf planets, and Charon is officially classified as a moon of Pluto.^[24]

On July 14, 2015, the Pluto system is due to be visited by spacecraft for the first time. The New Horizons probe will perform a flyby during which it will attempt to take detailed measurements and images of the plutoid and its moons.

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Uranus the 7th planet solar system

Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest Solar System. Uranus is similar in composition to Neptune, and both are of different chemical composition to the larger gas giants Jupiter and Saturn. Thus, astronomers sometimes place them in a separate category called "ice giants". Uranus's atmosphere, although similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, contains more "ices", such as water, ammonia, and methane, along with traces of hydrocarbons.^[12] It is the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224.2 °C), and has a complex, layered cloud structure, with water thought to make up the lowest clouds, and methane the uppermost layer of clouds. In contrast, the interior of Uranus is mainly composed of ices and rock.

planetary mass in the

It is the only planet whose name is derived from a figure from Greek mythology rather than Roman mythology like the other planets, from the Latinized version of the Greek god of the sky, Ouranos. Like the other giant planets, Uranus has a ring system, a magnetosphere, and numerous moons. The Uranian system has a unique configuration among those of the planets because its axis of rotation is tilted sideways, nearly into the plane of its revolution about the Sun. Its north and south poles therefore lie where most other planets have their equators.^[16] In 1986, images from Voyager 2 showed Uranus as a virtually featureless planet in visible light without the cloud bands or storms associated with the other giants. Terrestrial observers have seen signs of seasonal change and increased weather activity in recent years as Uranus approached its equinox. The wind speeds on Uranus can reach 250 meters per second (900 km/h, 560 mph).

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Why Our Standard Candle Isn’t Really Standard

When a runaway thermonuclear explosion rips through a white dwarf star and blows the star to bits, it’s called a type 1a supernova. These explosions are incredibly violent and incredibly bright, sometimes outshining entire galaxies. Thought to occur about once every two centuries in a galaxy like the Milky Way, these stellar cataclysms are relatively frequent events.

The star doing the exploding is a white dwarf with a fairly standard mass, so the supernova’s brightness is predictable. And because luminosity decreases with distance, scientists can use the difference between an explosion’s observed and predicted brightness to determine how far away the blazing starstuff is. That characteristic has led to type 1a supernovae being called “cosmic mile markers” and “standard candles.”

There’s controversial evidence for the presence of an ex-companion star in Tycho’s supernova remnant. The explosion happened in 1572. (NASA/CXC/Chinese Academy of Sciences/F. Lu)

In the late 1990s, distance measurements based on type 1a supernovae revealed that the expanding universe is accelerating. In other words, it’s flying apart more quickly now than it was billions of years ago. Scientists still don’t know exactly what’s going on, but they attribute the phenomenon to an enigmatic thing called dark energy. The discovery represented a fundamental shift in cosmology and earned the Nobel Prize in physics in 2011.

But here’s the thing: Despite their crucial cosmological importance, type 1a supernovae are still very much a mystery. As astronomers study more and more of them, it’s becoming increasingly clear just how non-standard these explosions actually are – and how little we really know about them.

“They’re standardizable candles, not standard candles,” astrophysicist Brad Tucker told me a bit ago, while I was working on a feature describing type 1a supernovae for the Proceedings of the National Academy of Sciences. Tucker splits his time between UC Berkeley and the Australian National University.

“These are very powerful tools in cosmology,” he said. “But we really don’t know what’s going on with them.”

It’s true. The uncertainties swirling around these fascinating explosions are kind of astonishing. Here are a few.

1. Until now, there was no proof that white dwarfs were doing the exploding.

For starters, we didn’t have solid observational evidence pointing to white dwarfs as the culprits behind type 1a supernovae until earlier this year, as reported yesterday in the journal Nature. Decades of solid theoretical work (and circumstantial evidence) suggested as much, but the observations weren’t there to back it up.

But in January, a star exploded in the Cigar Galaxy. Essentially next door at only 11.5 million light-years away, it was the closest type 1a supernova to Earth in four centuries. Chemical signatures in the billowing debris cloud revealed that supernova 2014J, as it’s called, is a type 1a supernova. Because the explosion was so nearby, astronomers were able to detect gamma-rays coming from the debris, a type of radiation that hasn’t been observable in other type 1a supernovae.

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The Monkey Head Nebula Is a Glittering Stellar Nursery

Peer closely at this photo and in the background, you’ll see galaxies the size of stars, and stars the size of huge version here]. But in the foreground is the Monkey Head Nebula (NGC 2174), captured in the infrared by the Hubble space telescope. It’s a region of wispy, turbulent gas and dust clouds — chaos enveloping a twinkling stellar nursery. This beautiful patch of starry sky is in the constellation Orion, about 6,500 light-years away. The nebula gets its name from the shape it takes when viewed in wide-field. This image doesn’t really give you the full primate-in-the-sky experience, so I’ve used that as an excuse to paste in a set of photos below. Sit back and stare, click to enlarge. 

galaxies

The Monkey Head' Nebula (Youtube)

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Mission to Pluto Is Like a Next-Gen Voyager

Yesterday, a cosmic coincidence brought together two spacecraft. One, a veteran cosmic explorer, is hurtling

ever outward toward the hinterlands of the solar system. The curtain is still waiting to rise on the other, a relative youngster that will soon be stepping into the spotlight.

On August 25, the Pluto-destined New Horizons spacecraft crossed Neptune’s orbit — 25 years to the day after its elder sibling, Voyager 2, swooped in for a close look at the big, blue ice giant and its curious, geyser-spewing moon.

That cosmic collusion of events helps mark the passing of a torch from one generation of space explorers to another, scientists said during a press conference commemorating the occasion.

A quarter-century ago, Voyager 2 beamed the first good images of Neptune back to Earthly eyes. Now, of course, Neptune isn’t anywhere near where it was then. But that didn’t stop New Horizons from snapping a quick photo as it zoomed over Neptune’s invisible footsteps. From 4 billion kilometers away, the giant planet and its weird moon Triton appear as nothing more than a few tiny pixels, a bit brighter than the inky black background.

For many, exploring the Pluto system will be the modern equivalent of the Voyager mission, says New Horizons principal investigator Alan Stern.

“This is the first opportunity in a generation to really explore a new planetary system for the first time,” he said. “When I was growing up, we had the privilege of seeing the first orbiter at Mars, and the first landers. And then, the first missions to Jupiter, to Saturn and Uranus and Neptune. And they were enthralling. And they were mind-blowing in terms of the richness of nature. But there hasn’t been anything like this yet in a long time.”

I think it’s safe to say that the spotlight will be firmly fixed on New Horizons when it pulls up next to Pluto in July 2015 and sends those first detailed images of the dwarf planet back to Earth. It’ll be like sending a long-awaited interplanetary postcard to millions of people at once.

Pluto is the most farflung system we will have explored. That enormous distance means we know relatively little about the tiny planet, which is faint and hard to see, even for the most powerful telescopes. “Even with all of our modern technology, everything we know about the Pluto system today would probably fit on one piece of paper,” Stern said, gesturing to a regular old piece of paper.

The same could probably be said for several of the giant planets in the 1980s. Putting the issues of politics and funding aside, these are stories of discovery on the grandest scale, of visiting new worlds and revealing new vistas.

Erupting Ice

Take Neptune, for example. Until Voyager arrived in 1989, the planet was a small blue smear in the sky. But Voyager saw much more than that. Fragments of rings gracefully hugged the space near the planet’s equator. A storm the size of Earth left a large, dark blue blotch on the cerulean surface (the Great Dark Spot had disappeared by the time Hubble aimed its eye at Neptune five years later). Methane clouds high in Neptune’s atmosphere hovered in relief above the otherwise smooth, gassy world. “The planet also had the highest speed winds of any that we had seen in the solar system — over 1,000 milers per hour,” says Voyager project scientist Ed Stone. “We were surprised to find such an active atmosphere so far from the sun.”

High altitude clouds streak Neptune’s atmosphere. (NASA/JPL)

And then there was Neptune’s strange little moon, Triton. Before Voyager arrived, teams had no idea what they would find. Unlike some of the other outer planet moons, Triton was not formed in the same neighborhood as Neptune. Instead, it grew up far, far away, in a region known as the Kuiper Belt. That distant band of rocky objects is home to the likes of Pluto and its dwarfy brethren.

“Triton was captured by Neptune and probably had geologic activity early in its history. But we had no idea, really, what it was going to look like,” Stone says. “There were many surprises ahead for us.”

The flyby revealed an active world with strange surface features (dubbed “cantaloupe terrain”), fractures, icy lava and geysers strewing dark material across the moon’s bright polar cap. “Even at the most remote edges, we have an active, alive surface on this cold little moon,” Stone says.

Now, a new animation using re-processed images from Voyager recreates that early flyby.

Voyager 2 Encounter with Triton(Youtube)

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Milky Way is on the outskirts of 'immeasurable heaven' supercluster

Astronomers discover that our galaxy is a suburb of a supercluster of 100,000 large galaxies they have called

Laniakea

In what amounts to a back-to-school gift for pupils with nerdier leanings, researchers have added a fresh line to the cosmic address of humanity. No longer will a standard home address followed by "the Earth, the solar system, the Milky Way, the universe" suffice for aficionados of the extended astronomical location system.

The extra line places the Milky Way in a vast network of neighbouring galaxies or "supercluster" that forms a spectacular web of stars and planets stretching across 520m light years of our local patch of universe. Named Laniakea, meaning "immeasurable heaven" in Hawaiian, the supercluster contains 100,000 large galaxies that together have the mass of 100 million billion suns.

Our home galaxy, the Milky Way, lies on the far outskirts of Laniakea near the border with another supercluster of galaxies named Perseus-Pisces. "When you look at it in three dimensions, is looks like a sphere that's been badly beaten up and we are over near the edge, being pulled towards the centre," said Brent Tully, an astronomer at the University of Hawaii in Honolulu.

Astronomers have long known that just as the solar system is part of the Milky Way, so the Milky Way belongs to a cosmic structure that is much larger still. But their attempts to define the larger structure had been thwarted because it was impossible to work out where one cluster of galaxies ended and another began.

Video from Youtube

Tully's team gathered measurements on the positions and movement of more than 8,000 galaxies and, after discounting the expansion of the universe, worked out which were being pulled towards us and which were being pulled away. This allowed the scientists to define superclusters of galaxies that all moved in the same direction (if you're reading this story on a mobile device, click here to watch a video explaining the research).

The work published in Nature gives astronomers their first look at the vast group of galaxies to which the Milky Way belongs. A narrow arch of galaxies connects Laniakea to the neighbouring Perseus-Pisces supercluster, while two other superclusters called Shapley and Coma lie on the far side of our own.

Tully said the research will help scientists understand why the Milky Way is hurtling through space at 600km a second towards the constellation of Centaurus. Part of the reason is the gravitational pull of other galaxies in our supercluster.

"But our whole supercluster is being pulled in the direction of this other supercluster, Shapley, though it remains to be seen if that's all that's going on," said Tully.

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The sun: Chemical composition

The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and metals in astronomy, account for less than 2% of the mass. The most abundant metals are oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon (0.2%), and iron (0.2%). 

23.8% of the mass of the Sun in the photosphere, respectively. All heavier elements, called

The Sun inherited its chemical composition from the interstellar medium out of which it formed. The hydrogen and helium in the Sun were produced by Big Bang nucleosynthesis, and the metals were produced by stellar nucleosynthesis in generations of stars that completed their stellar evolution and returned their material to the interstellar medium before the formation of the Sun. The chemical composition of the photosphere is normally considered representative of the composition of the primordial Solar System. However, since the Sun formed, some of the helium and heavy elements have gravitationally settled from the photosphere. Therefore, in today's photosphere the helium fraction is reduced and the metallicity is only 84% of that in the protostellar phase (before nuclear fusion in the core started). The protostellar Sun's composition was reconstructed as 71.1% hydrogen, 27.4% helium, and 1.5% metals. 

In the inner portions of the Sun, nuclear fusion has modified the composition by converting hydrogen into helium, so the innermost portion of the Sun is now roughly 60% helium, with the metal abundance unchanged. Because the interior of the Sun is radiative, not convective (see Radiative zone above), none of the fusion products from the core have risen to the photosphere. 

The reactive core zone of "hydrogen burning", where hydrogen is converted into helium, is starting to surround the core of "helium ash". This development will continue and will eventually cause the Sun to leave the main sequence, to become a red giant

The solar heavy-element abundances described above are typically measured both using spectroscopy of the Sun's photosphere and by measuring abundances in meteorites that have never been heated to melting temperatures. These meteorites are thought to retain the composition of the protostellar Sun and are thus not affected by settling of heavy elements. The two methods generally agree well.^[15]

Singly ionized iron group elements

In the 1970s, much research focused on the abundances of iron group elements in the Sun. Although significant research was done, the abundance determination of some iron group elements (e.g. cobalt and manganese) was still difficult at least as far as 1978 because of their hyperfine structures.

The first largely complete set of oscillator strengths of singly ionized iron group elements were made available first in the 1960s, and improved oscillator strengths were computed in 1976. In 1978 the abundances of 'singly Ionized' elements of the iron group were derived.

Solar and planetary mass fractionation relationship

Various authors have considered the existence of a mass fractionation relationship between the isotopic compositions of solar and planetary noble gases, for example correlations between isotopic compositions of planetary and solar neon and xenon. Nevertheless, the belief that the whole Sun has the same composition as the solar atmosphere was still widespread, at least until 1983.

In 1983, it was claimed that it was the fractionation in the Sun itself that caused the fractionation relationship between the isotopic compositions of planetary and solar wind implanted noble gases.

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Earth, Orbit and rotation

Rotation

 Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time (86,400.0025 SI seconds). As the Earth's solar day is now slightly longer than it was during the 19th century due to tidal acceleration, each day varies between 0 and 2 SI ms longer.

Earth's rotation period relative to the fixed stars, called its stellar day by the International Earth Rotation and Reference Systems Service (IERS), is 86,164.098903691 seconds of mean solar time (UT1), or 23^h 56^m 4.098903691^s.^{[2][n 12]} Earth's rotation period relative to the precessing or moving mean vernal equinox, misnamed its sidereal day, is 86,164.09053083288 seconds of mean solar time (UT1) (23^h 56^m 4.09053083288^s) as of 1982.^[2] Thus the sidereal day is shorter than the stellar day by about 8.4 ms.^[129] The length of the mean solar day in SI seconds is available from the IERS for the periods 1623–2005^[130] and 1962–2005.

Apart from meteors within the atmosphere and low-orbiting satellites, the main apparent motion of celestial bodies in the Earth's sky is to the west at a rate of 15°/h = 15'/min. For bodies near the celestial equator, this is equivalent to an apparent diameter of the Sun or Moon every two minutes; from the planet's surface, the apparent sizes of the Sun and the Moon are approximately the same.

Orbit

Main article: Earth's orbit

Earth orbits the Sun at an average distance of about 150 million kilometers every 365.2564 mean solar days, or one sidereal year. From Earth, this gives an apparent movement of the Sun eastward with respect to the stars at a rate of about 1°/day, which is one apparent Sun or Moon diameter every 12 hours. Due to this motion, on average it takes 24 hours—a solar day—for Earth to complete a full rotation about its axis so that the Sun returns to the meridian. The orbital speed of the Earth averages about 29.8 km/s (107,000 km/h), which is fast enough to travel a distance equal to the planet's diameter, about 12,742 km, in seven minutes, and the distance to the Moon, 384,000 km, in about 3.5 hours.

The Moon revolves with the Earth around a common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common revolution around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the motion of Earth, the Moon and their axial rotations are all counterclockwise. Viewed from a vantage point above the north poles of both the Sun and the Earth, the Earth revolves in a counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.4 degrees from the perpendicular to the Earth–Sun plane (the ecliptic), and the Earth–Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses.

The Hill sphere, or gravitational sphere of influence, of the Earth is about 1.5 Gm or 1,500,000 km in radius.^{[135][n 13]} This is the maximum distance at which the Earth's gravitational influence is stronger than the more distant Sun and planets. Objects must orbit the Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun.

Earth, along with the Solar System, is situated in the Milky Way galaxy and orbits about 28,000 light years from the center of the galaxy. It is about 20 light years above the galactic plane in the Orion spiral arm.

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Earth, Composition and structure

Earth is a terrestrial planet, meaning that it is a rocky body, rather than a gas giant like Jupiter. It is the largest surface gravity, the strongest magnetic field, and fastest rotation, and is probably the only one with active plate tectonics.

of the four terrestrial planets in size and mass. Of these four planets, Earth also has the highest density, the highest

The shape of the Earth approximates an oblate spheroid, a sphere flattened along the axis from pole to pole such that there is a bulge around the equator.^[57] This bulge results from the rotation of the Earth, and causes the diameter at the equator to be 43 km (kilometer) larger than the pole-to-pole diameter.^[58] Thus the furthest point on the surface from the Earth's center of mass is the Chimborazo volcano in Ecuador.^[59] The average diameter of the reference spheroid is about 12742 km, which is approximately 40,000 km/π, as the meter was originally defined as 1/10,000,000 of the distance from the equator to the North Pole through Paris, France.^[60]

Local topography deviates from this idealized spheroid, although on a global scale, these deviations are small: Earth has a tolerance of about one part in about 584, or 0.17%, from the reference spheroid, which is less than the 0.22% tolerance allowed in billiard balls.^[61] The largest local deviations in the rocky surface of the Earth are Mount Everest (8,848 m above local sea level) and the Mariana Trench (10911 m below local sea level). Due to the equatorial bulge, the surface locations farthest from the center of the Earth are the summits of Mount Chimborazo in Ecuador and Huascarán in Peru.

 

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Video NASA Discovers Earth2.0

An other earth in our galaxy?? It's possible??

 NASA discovered this..

 The next video provr that.

From youtube

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The core of the sun: It's magic

 The core of sun

The core of the Sun is considered to extend from the center to about 20–25% of the solar radius. It has a150 g/cm³ (about 150 times the density of water) and a temperature of close to 15.7 million kelvin (K). By contrast, the Sun's surface temperature is approximately 5,800 K. Recent analysis of SOHO mission data favors a faster rotation rate in the core than in the rest of the radiative zone. Through most of the Sun's life, energy is produced by nuclear fusion through a series of steps called the p–p (proton–proton) chain; this process converts hydrogen into helium. Only 0.8% of the energy generated in the Sun comes from the CNO cycle.

density of up to

The core is the only region in the Sun that produces an appreciable amount of thermal energy through fusion; 99% of the power is generated within 24% of the Sun's radius, and by 30% of the radius, fusion has stopped nearly entirely. The rest of the star is heated by energy that is transferred outward by radiation from the core to the convective layers just outside. The energy produced by fusion in the core must then travel through many successive layers to the solar photosphere before it escapes into space as sunlight or the kinetic energy of particles.

The proton–proton chain occurs around 9.2×10³⁷ times each second in the core. Since this reaction uses four free protons (hydrogen nuclei), it converts about 3.7×10³⁸ protons to alpha particles (helium nuclei) every second (out of a total of ~8.9×10⁵⁶ free protons in the Sun), or about 6.2×10¹¹ kg per second.^[18] Since fusing hydrogen into helium releases around 0.7% of the fused mass as energy,^[54] the Sun releases energy at the mass–energy conversion rate of 4.26 million metric tons per second, 384.6 yotta watts (3.846×10²⁶ W),^[1] or 9.192×10¹⁰ megatons of TNT per second.

The power production by fusion in the core varies with distance from the solar center. At the center of the Sun, theoretical models estimate it to be approximately 276.5 watts/m³,^[55] a power production density that more nearly approximates reptile metabolism than a thermonuclear bomb.^[d] Peak power production in the Sun has been compared to the volumetric heats generated in an active compost heap. The tremendous power output of the Sun is not due to its high power per volume, but instead due to its large size.

The fusion rate in the core is in a self-correcting equilibrium: a slightly higher rate of fusion would cause the core to heat up more and expand slightly against the weight of the outer layers, reducing the fusion rate and correcting the perturbation; and a slightly lower rate would cause the core to cool and shrink slightly, increasing the fusion rate and again reverting it to its present level.^[56][57]

The gamma rays (high-energy photons) released in fusion reactions are absorbed in only a few millimeters of solar plasma and then re-emitted again in a random direction and at slightly lower energy. Therefore it takes a long time for radiation to reach the Sun's surface. Estimates of the photon travel time range between 10,000 and 170,000 years.^[58] In contrast, it takes only 2.3 seconds for the neutrinos, which account for about 2% of the total energy production of the Sun, to reach the surface. Since energy transport in the Sun is a process which involves photons in thermodynamic equilibrium with matter, the time scale of energy transport in the Sun is longer, on the order of 30,000,000 years. This is the time it would take the Sun to return to a stable state if the rate of energy generation in its core were suddenly to be changed.^[59]

During the final part of the photon's trip out of the Sun, in the convective outer layer, collisions are fewer and far between, and they have less energy. The photosphere is the transparent surface of the Sun where the photons escape as visible light. Each gamma ray in the Sun's core is converted into several million photons of visible light before escaping into space. Neutrinos are also released by the fusion reactions in the core, but unlike photons they rarely interact with matter, so almost all are able to escape the Sun immediately. For many years measurements of the number of neutrinos produced in the Sun were lower than theories predicted by a factor of 3. This discrepancy was resolved in 2001 through the discovery of the effects of neutrino oscillation: the Sun emits the number of neutrinos predicted by the theory, but neutrino detectors were missing ²⁄₃ of them because the neutrinos had changed flavor by the time they were detected

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The magic black Hole (Video)

See the black hole on video... it's magic and danger dream

Let' see the video tougether

From Youtube

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Natural satellite of our solar system

A natural satellite, or moon, is a celestial body that orbits another body, e.g. a planet, which is called its . There are 173 known natural satellites orbiting planets in the Solar System, as well as at least eight orbiting IAU-listed dwarf planets. As of January 2012, over 200 minor-planet moons have been discovered.^[4] There are 76 known objects in the asteroid belt with satellites (five with two satellites each), four Jupiter trojans, 39 near-Earth objects (two with two satellites each), and 14 Mars-crossers. There are also 84 known natural satellites of trans-Neptunian objects. Some 150 additional small bodies have been observed within rings of Saturn, but only a few were tracked long enough to establish orbits. Planets around other stars are likely to have satellites as well, though numerous candidates have been detected to date, none have yet been confirmed.

primary

Of the inner planets, Mercury and Venus have no natural satellites; Earth has one large natural satellite, known as the Moon; and Mars has two tiny natural satellites, Phobos and Deimos. The large gas giants have extensive systems of natural satellites, including half a dozen comparable in size to Earth's Moon: the four Galilean moons, Saturn's Titan, and Neptune's Triton. Saturn has an additional six mid-sized natural satellites massive enough to have achieved hydrostatic equilibrium, and Uranus has five. It has been suggested that some satellites may potentially harbour life, though there is currently no direct evidence of life.

The Earth–Moon system is unique in that the ratio of the mass of the Moon to the mass of the Earth is much greater than that of any other natural-satellite–planet ratio in the Solar System (although there are minor-planet systems with even greater ratios, notably the Pluto–Charon system).

Among the dwarf planets, Ceres and Makemake have no known natural satellites. Pluto has the relatively large natural satellite Charon and four smaller natural satellites. Haumea has two natural satellites, and Eris has one. The Pluto–Charon system is unusual in that the center of mass lies in open space between the two, a characteristic sometimes associated with a double-planet system.

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Mercury: The first and nearly planet to sun

Mercury is the smallest and closest to the Sun of the eight planets in the Solar System, with an orbital period Earth days. Seen from Earth, it appears to move around its orbit in about 116 days, which is much faster than any other planet. It has no known natural satellites. The planet is named after the Roman deity Mercury, the messenger to the gods.

of about 88

Because it has almost no atmosphere to retain heat, Mercury's surface experiences the greatest temperature variation of all the planets, ranging from 100 K (−173 °C; −280 °F) at night to 700 K (427 °C; 800 °F) during the day at some equatorial regions. The poles are constantly below 180 K (−93 °C; −136 °F). Mercury's axis has the smallest tilt of any of the Solar System's planets (about ¹⁄₃₀ of a degree), but it has the largest orbital eccentricity.^[a] As such it does not experience seasons in the same way as most other planets such as Earth. At aphelion, Mercury is about 1.5 times as far from the Sun as it is at perihelion. Mercury's surface is heavily cratered and similar in appearance to the Moon, indicating that it has been geologically inactive for billions of years.

Mercury is gravitationally locked and rotates in a way that is unique in the Solar System. As seen relative to the fixed stars, it rotates exactly three times for every two revolutions^[c] it makes around its orbit.^[13] As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two years.

Because Mercury moves in an orbit around the Sun which lies within Earth's orbit (as does Venus), it can appear in Earth's sky in the morning or the evening, but not in the middle of the night. Also, like Venus and the Moon, it displays a complete range of phases as it moves around its orbit relative to Earth. Although Mercury can appear as a bright object when viewed from Earth, its proximity to the Sun makes it more difficult to see than Venus. Two spacecraft have visited Mercury: Mariner 10 flew by in the 1970s and MESSENGER, launched in 2004, remains in orbit.

 

Mercury planet

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Venus: The 2nd planet solar system

Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has no natural satellite. It isRoman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°.

named after the

Venus is a terrestrial planet and is sometimes called Earth's "sister planet" because of their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). However, it has also been shown to be radically different from Earth in other respects. It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the planet's surface is 92 times that of Earth's. With a mean surface temperature of 735 K (462 °C; 863 °F), Venus is by far the hottest planet in the Solar System. It has no carbon cycle to lock carbon back into rocks and surface features, nor does it seem to have any organic life to absorb it in biomass. Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light. Venus may have possessed oceans in the past,^[13][14] but these would have vaporized as the temperature rose due to a runaway greenhouse effect. The water has most probably photodissociated, and, because of the lack of a planetary magnetic field, the free hydrogen has been swept into interplanetary space by the solar wind. Venus's surface is a dry desertscape interspersed with slab-like rocks and periodically refreshed by volcanism.

 Venus

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