Astronotes Armagh Planetarium's Stellar Blog! ... Solar System . ... The theory is known as the Grand Tack as according to it, during the first 10 million years of the Solar systemтАЩs existence Jupiter migrated inwards toward the Sun before turning and coming back, sweeping away all debris that fell into its path. ... Another widely-accepted theory of the formation of the Solar System, the delightfully-named Nice model neatly ties in with the Grand Tack theory as they both support each other. ...

... The discovery of giant Jupiter-type planets in a close proximity to 51 Peg, Boo, and And has prompted the question of where the planets could be formed in the circumstellar disks of solar-type stars. ... Planet formation, at distance of ~0.05 AU from the star, requires that the temperature of the circumstellar protoplanetary disk is low enough for the condensation of rocky materials, and the surface density is sufficiently high. ...

The solar system probably formed about 4.5 billion years ago from a giant disk of gas, dust and ice in space. ... All forms of life on Earth require liquid water to survive, so the presence of liquid water is a good criterion for deciding whether other planets in the universe could be habitable. Earth is the only habitable planet in the solar system. Venus, closer to the Sun, is too hot to have liquid water. Planets and moons in the outer solar system are too cold for liquid water. ...

... New research shows how circumbinary planets form . ... Luke Skywalker s home planet Tatooine would have formed far from its current location in the Star Wars universe, a new University of Bristol study into its real world counterparts, observed by the Kepler space telescope, suggests. ... Circumbinary planets have captured the imagination of many science-fiction writers and film makers; our research shows just how remarkable such planets are, said Stefan Lines from the University of Bristol. ...

3) Planets and Brown Dwarfs . ... By its nature, this method is most sensitive to massive planets orbiting close to their stars. ... That means that some of the more massive extrasolar planets could actually be brown dwarfs (although the statistics of the finds suggest that most of them are not). ... Another possible difference between brown dwarfs and massive planets is how they are born. ... They would base the fundamental definition on the mode of formation: a planet is built from planetesimals. ...

Astronomy Picture of the Day . Uranus: The Tilted Planet . ... This picture was snapped by the Voyager 2 spacecraft in 1986 - the only spacecraft ever to visit Uranus. ... Irregular Galaxy Sextans A . ... But small irregular galaxies form stars too, like this lovely, gumdrop-shaped galaxy, Sextans A. Mars: A Sheer Close Up . ... The Annotated Galactic Center . ... The new large black spot reveals that a volcano named Pillan Patera has been erupting during the interim. ...

... 8, ``Celestial Mechanics'', 2002 Formation and migration of trans -- Neptunian objects S. I. Ipatov 1;2 1 Institute of Applied Mathematics, Moscow, Russia 2 NASA/GSFC, Greenbelt, USA We support the Eneev's idea [1] that the largest (with diameter d?100 km) trans ­ Neptunian objects ( TNOs ) moving now in not very eccentric orbits ... The total amount of water delivered to the Earth during the formation of the giant planets was about the mass of water in the Earth's oceans. ...

. Mars has become the center of intense interest since the Martian Meteorite results were announced. Currently there is a lively debate whether or not primitive life formed there or not.

... Did you know that you're made of stardust? ... Almost everything is made up of materials that were formed in the centre of a star. Anything that wasn't made in a star, is made from the same material as stars gas planets, like Jupiter and Saturn, for example. Once you know that planets are made from the leftover material around forming stars, this makes sense! When a star is born, deep in a cloud of gas and cosmic dust, any leftover material forms a disc around it (like Saturn's rings). ...

... 2001 June 4 . The T Tauri Star Forming System . ... A prototype laboratory for the formation of low mass stars like our Sun is the T Tauri system , one of the brighter star systems toward the constellation of Taurus . In young systems , gravity causes a gas cloud to condense. The situation then usually becomes quite complex, as some of the infalling gas is heated so much by collisions that it is immediately expelled as an outgoing wind . ... About APOD | ...

... B ut Europa's surface is not at all like anything in the inner solar system. ... T he images of Europa's surface strongly resemble images of sea ice on Earth. It is possible that beneath Europa's surface ice there is a layer of liquid water , perhaps as much as 50 km deep, kept liquid by tidally generated heat. ... It is most likely generated by sunlight and charged particles hitting Europa's icy surface producing water vapor which is subsequently split into hydrogen and oxygen. ...

Saturn: The beauty of the rings. Saturn . ... Belongs to the giant planets . It has no definite solid surface. ... The free fall acceleration at the Saturn surface near equator is 9,06 m/s^2 . ... In the centre of the planet the temperature is about 20000K. The satellites . ... The rings of Saturn . ... It is prove