Secret Behind Jupiter's Giant Size

Jupiter is the largest planet in the solar system. 120 times the size of Earth. However, recent measurements by the spacecraft reveal the planet’s core at most 10 times the size of the planet we inhabit.Recent studies found that about Jupiter, the giant planet has a core of very small compared with the size. Scientists believe, so the planet Jupiter, the largest in the Milky Way Galaxy because he swallowed the other small planets, before the swell.

As disclosed in the site of science, New Scientist, the core of Jupiter thought to have greater evaporation in a collision with a planet the size 10 times the size of Earth. This study provides new insight into a process that is fierce in the early formation of our solar system.Researchers from Peking University, China has to imitate what might happen in the event that the collision. The simulation results show, rocky planets closer to Jupiter will be demolished as it hit the giant planet’s atmosphere.

Half an hour later, the planet would fall into the core of Jupiter. Heavy elements in the core as the metal will evaporate and then mixed with hydrogen and helium in the atmosphere of Jupiter. Scientists believe this may explain why the core of Jupiter is very small but extremely dense atmosphere.Douglas Lin of the University of California, said that while the smaller planet does not bump into him, Jupiter will continue to grow into a giant planet itself.

The research team said, elements in the planet Saturn may also be caused by something similar, a collision with a smaller planet.The planets in our solar system created by collisions between dwarf planets that orbit the Sun, who was also born. In the process the impact, small planets to melt and form planets is greater.

Earth and Moon are the result of a collision between two giant planets about the size of Mars and Venus.Collision process occurs in less than 24 hours, and the temperature of the earth at that time was very high, around 7000 degrees Celsius, where rock and metal can be melted.

Astronomers find loads of water-ice on big asteroid

A slushy cocktail of water-ice and organic materials has been directly detected on the surface of an asteroid for the first time. The finding strengthens the theory that asteroids delivered the ingredients for Earth’s oceans and life, and could make astronomers rethink conventional models for how the Solar System evolved.

It has long been thought that asteroids, which lie in a belt between Mars and Jupiter, are rocky bodies that sit too close to the Sun to retain ice. By contrast, comets, which form further out beyond Neptune, are ice-rich bodies that develop distinctive tails of vaporized gas and dust when they approach the Sun. However, this distinction was blurred in 2006 by the discovery of small objects with comet-like tails in the asteroid belt1, says astronomer Andrew Rivkin of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.To investigate the composition of these ‘main-belt comets’, Rivkin and his colleague Joshua Emery, of the University of Tennessee in Knoxville, turned the infra-red telescope at Mauna Kea, Hawaii, onto the asteroid 24 Themis — the parent body from which two of the smaller comet-like asteroids observed in 2006 were chipped. Emery and Rivkin took seven measurements of 24 Themis over a period of six years, each time looking at a different face of the asteroid as it travelled around its orbit. They consistently found a band in the absorption spectrum of light reflected from its surface that indicated the presence of grains coated in water ice, as well as the signature of carbon-to-hydrogen chemical bonds — as found in organic materials. Rivkin and Emery’s work is published in this week’s Nature2.

“Astronomers have looked at dozens of asteroids with this technique, but this is the first time we’ve seen ice on the surface and organics,” says Rivkin. The result was independently confirmed by a team led by Humberto Campins at the University of Central Florida in Orlando. He and his colleagues observed 24 Themis for 7 hours one night, as it almost fully rotated on its axis. “Between us, we have seen the asteroid from almost every angle and we see global coverage,” says Campins. He and his team also publish their findings in this week’s Nature3.

Julie Castillo-Rogez, an astrophysicist at NASA’s Jet Propulsion Laboratory in Pasadena, California, describes the findings as “huge”. “This answers the long-term question of whether there is free water in the asteroid belt,” she says.
Icy interloper

Because 24 Themis lies only about 479 million kilometres from the Sun (roughly three times the mean distance from Earth to the Sun), it is surprising that the surface ice has not all been vaporized. Both teams speculate that more ice may be held in a reservoir beneath the asteroid’s surface, shielded from the Sun, and that this ice is slowly churned up as the asteroid is struck by small bodies in the belt, thus replenishing the surface ice.The findings lend weight to the idea that asteroids and comets are the source of Earth’s water and organic material. Geochemists think that the early Earth went through a molten phase when any organic molecules would have dissociated, so new organic material would have had to be delivered to the planet at a later time, says Campins. “I believe our findings are linked to the origin of life on Earth,” he says.To assess the plausibility of this scenario, astronomers must determine whether the make-up of 24 Themis is typical of other asteroids and, if so, what exactly they hold, says Castillo-Rogez. A priority should be to search for water ice on near-Earth asteroids that could be targeted by NASA’s planned robotic and manned missions. “If we find ice samples that contain the same ratio of deuterium [‘heavy hydrogen’ made up of one neutron and one proton] to hydrogen as seen on Earth, that would be a strong pointer,” she says.

However, 24 Themis may not be a typical member of the belt it could be an interloper that formed beyond Neptune, along with the comets, which was later knocked inwards, says Rivkin. If so, this would fit well with the controversial ‘Nice model’ of the evolution of the Solar System. Proposed in 2005, this model suggests that the giant planets Jupiter, Saturn, Uranus and Neptune and asteroids migrated to their present orbits after formation4. Either way, says Rivkin, “The old-fashioned picture of the Solar System in which asteroids are asteroids and comets are comets is getting harder to sustain.”(nature)

Astronomers announcedthis week they found super-Earth/ GJ 1214b

super-Earth/ GJ 1214b

Astronomers announced this week they found a water-rich and relatively nearby planet that’s similar in size to Earth. While the planet probably has too thick of an atmosphere and is too hot to support life similar to that found on Earth, the discovery is being heralded as a major breakthrough in humanity’s search for life on other planets.”The big excitement is that we have found a watery world orbiting a very nearby and very small star,” said David Charbonneau, a Harvard professor of astronomy and lead author of an article on the discovery, which appeared this week in the journal Nature.
The planet, named GJ 1214b, is 2.7 times as large as Earth and orbits a star much smaller and less luminous than our sun. That’s significant, Charbonneau said, because for many years, astronomers assumed that planets only would be found orbiting stars that are similar in size to the sun.

Because of that assumption, researchers didn’t spend much time looking for planets circling small stars, he said. The discovery of this “watery world” helps debunk the notion that Earth-like planets could form only in conditions similar to those in our solar system.
“Nature is just far more inventive in making planets than we were imagining,” he said.In a way, the newly discovered planet was sitting right in front of astronomers’ faces, just waiting for them to look. Instead of using high-powered telescopes attached to satellites, they spotted the planet using an amateur-sized, 16-inch telescope on the ground. There were no technological reasons the discovery couldn’t have happened long ago, Charbonneau said.The planet is also rather near to our solar system — only about 40 light-years away.Planet GJ 1214b is classified as a “super-Earth” because it is between one and 10 times as large as Earth. Scientists have known about the existence of super-Earths for only a couple of years. Most planets discovered by astronomers have been gassy giants that are much more similar to Jupiter than to Earth.Charbonneau said it’s unlikely that any life on the newly discovered planet would be similar to life on Earth, but he didn’t discount the idea entirely.

Lithium clue for planet-hunters

A survey of stars known to possess planets shows the vast majority to be severely depleted in lithium.To date, scientists have detected just over 420 worlds circling other stars using a range of techniques.Garik Israelian and colleagues tell the journal Nature that future planet hunts could be narrowed by going after stars with particular compositions.Scientists think events early in the star’s formation may be responsible for producing the lithium phenomenon.Theory holds that planets grow from a disc of dusty material that develops around infant stars.The researchers propose that this disc and its contents alter the young star’s spin, mixing its upper layers more effectively into the interior where its contents can be “burnt” in the fusion processes that power it.

“When discs form around stars there is interaction of angular momentum between disc, planets and parent star; and this interaction affects the rotation of the parent star and that will affect the lithium abundance,” said Garik Israelian from the Instituto de Astrofisica de Canarias, Tenerife, Spain.The relative low abundance of lithium in our Sun’s upper layers has long been a fascination for scientists.

Researchers who have studied meteorites with compositions unchanged since the beginning of the Solar System say the element’s presence in our star ought to be 140 times greater than is observed.Physicists know the Sun’s upper layers as viewed today do not convect deeply enough to take any lithium to a location that is sufficiently hot to burn the element. This suggests mixing conditions must have been different in the past.

The outcome of the research is a tool astronomers can now use to help pinpoint the right type of stars where they are likely to detect planets.”Suppose you had 50 or 100 candidates for parent-bearing stars,” explained Dr Israelian.”Those which have a very low abundance of lithium will be the best candidates around which you might find planets,” he told BBC News.

Astronomers detect exoplanets, as they are called, using a number of methods.One technique looks for the gravitational “wobble” a massive planet will induce in its parent star.Another approach is to monitor a star for extended periods in the hope a planet will pass across its face. This transit reveals the planet’s presence by making the star’s light dim ever so slightly.(daily mail)