Modest Chaos in the Early Solar System
http://aasnova.org/2016/11/08/modest-chaos-in-the-early-solar-system/
The puzzling architecture of the Solar system has long been a headache for planetary dynamicists. We can sort of divide its structure
(cover image, not to scale) into several zones. First, the terrestrial planets Mercury, Venus, Earth and Mars, which are divided from
the gas and ice giant planets by the asteroid belt. Beyond the ice giants there is the Kuiper belt, which spans out to very large
distances from the Sun. One longstanding conundrum in this ordering is the relatively small mass of Mars and existence of the asteroid
belt in between Mars and Jupiter. It shouldn’t be there, and Mars should be way bigger. In fact, Mars is only 10% of the mass of Earth
and therefore seems to have never accreted enough material to become a fully fledged planet. In planet formation, Mars-sized objects
are usually termed “planetary embryos”, as we think this is the intermediate stage of a planet’s growth.
