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Archive for the ‘Solar System Formation’ Category

Series of Bumps Knocked Uranus Sideways

October 10, 2011 Leave a comment

Credit: Lawrence Sromovsky, (Univ. Wisconsin-Madison), Keck Observatory.

Credit: Lawrence Sromovsky, (Univ. Wisconsin-Madison), Keck Observatory.

Uranus’s highly tilted axis makes it something of an oddball in our Solar System. The accepted wisdom is that Uranus was knocked on its side by a single large impact, but new research to be presented on Thursday 6th October at the EPSC-DPS Joint Meeting in Nantes rewrites our theories of how Uranus became so tilted and also solves fresh mysteries about the position and orbits of its moons. By using simulations of planetary formation and collisions, it appears that early in its life Uranus experienced a succession of small punches instead of a single knock-out blow. This research has important ramifications on our theories of giant planet formation.

Uranus is unusual in that its spin axis is inclined by 98 degrees compared to its orbital plane around the Sun. This is far more pronounced than other planets, such as Jupiter (3 degrees), Earth (23 degrees), or Saturn and Neptune (29 degrees). Uranus is, in effect, spinning on its side.

The generally accepted theory is that in the past a body a few times more massive than the Earth collided with Uranus, knocking the planet on its side. There is, however, one significant flaw in this notion: the moons of Uranus should have been left orbiting in their original angles, but they too lie at almost exactly 98 degrees.

This long-standing mystery has been solved by an international team of scientists led by Alessandro Morbidelli (Observatoire de la Cote d’Azur in Nice, France), who will be presenting his group’s research on Thursday 6th October at the EPSC-DPS Joint Meeting in Nantes, France.

Full Story: http://www.europlanet-eu.org/outreach/index.php?option=com_content&task=view&id=359&Itemid=41

Did Earth’s Oceans Come from Comets?

October 7, 2011 Leave a comment

ESA’s Herschel infrared space observatory has found water in a comet with almost exactly the same composition as Earth’s oceans. The discovery revives the idea that our planet’s seas could once have been giant icebergs floating through space.

The origin of Earth’s water is hotly debated. Our planet formed at such high temperatures that any original water must have evaporated. Yet today, two-thirds of the surface is covered in water and this must have been delivered from space after Earth cooled down.

Comets seem a natural explanation: they are giant icebergs travelling through space with orbits that take them across the paths of the planets, making collisions possible. The impact of comet Shoemaker-Levy 9 on Jupiter in 1994 was one such event. But in the early Solar System, when there were larger numbers of comets around, collisions would have been much more common.

Full Story: http://www.esa.int/esaSC/SEMER89U7TG_index_0.html

NASA Partners Uncover New Hypothesis on Crater Debris

September 27, 2011 Leave a comment

A team of researchers partnered with the NASA Lunar Science Institute (NLSI) has developed a new hypothesis for the origin of crater ejecta–debris that is launched out of a crater during meteorite impacts.

These findings may help scientists target samples for extraction during future missions to asteroids and terrestrial bodies such as Mercury, Venus, the moon and Mars. The results are published in the Sept. 21, 2011, issue of the Elsevier journal, Earth and Planetary Science Letters.

The science team, led by professor Gordon Osinski at The University of Western Ontario, London, Ontario, compared observations of ejecta from all terrestrial planets. The observations showed that ejecta deposits all contained more than one layer.

Full Story: http://www.astronews.us/2011-09-27-0129.html

Solar System Likely Once Had Another Gas-Giant Planet

September 21, 2011 Leave a comment

Jupiter, Saturn, Uranus and Neptune. Those are the gas giants, the four heavyweights of the solar system. But was there once a fifth?

Maybe so, says a new study by David Nesvorny of the Southwest Research Institute in Boulder, Colorado. He used computer simulations to explore what the solar system may have looked like some four billion years ago.

Full Story: http://www.scientificamerican.com/podcast/episode.cfm?id=solar-system-likely-once-had-anothe-11-09-19