Mercury may be sole survivor of planetary pile-up The inner solar system may once have been a crowded and violent place – and Mercury its lone survivor. A new model suggests that most young planetary systems start with several close-in, rocky planets, which later destroy each other in a cascade of collisions. If forming tightly packed systems of inner planets is easy, theres no reason it shouldnt happen in our solar system, says Kathryn Volk at the University of British Columbia, Canada. And if it happened here, it would solve several problems. As astronomers discover more and more planets orbiting other stars, our solar system looks increasingly unusual. While we have four inner rocky planets and four outer gas giants, many other systems have hot Jupiters very close to their star. Whats more, observations by NASAs Kepler space telescope suggest that between 5 and 10 per cent of planetary systems cram several planets closer to their host star than Mercury is to the sun. Within our solar system, Mercury itself is an oddball. Its dense iron core takes up 42 per cent of its volume, its orbit is less circular than that of the other planets, and current planetary formation models predict Mercury should be closer to the sun and bigger, so we know were missing something. newscientist/article/dn26761-mercury-may-be-sole-survivor-of-planetary-pileup.html#.VLdUfivF-So
Posted on: Thu, 15 Jan 2015 05:52:14 +0000
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