Outer Planets & Debris, Page 16

Outer Planets & Debris, Page 16: [Previous Page] [Next Page] [Class Home Page] Textbook pages 283 - 284

Chaos in the Early Solar System

After a billion years of clean-up and meteoritic bombardment, you end up with ten or so planets, in stable orbits. However, various Catastrophes are needed to explain specific isolated features and exceptions. The planets, their surfaces and atmospheres may be heavily modified by the last, big collision they experience.

Examples of Chaos in our Solar System

Earth may have been hit late in its formation, there by producing our Moon.

Earth was continually bombarded with cometary objects, in order to explain our abundance of water (the original Earth could not have retained it).

Mercury's composition (dense), Venus' rotation (backwards) and Uranus' tilt (on its side)

The ring systems around the Gas Giants Movie

Might Uranus & Neptune have formed closer in, where nebular material was more abundant, and migrated out to their present orbits?

The Oort Cloud (presently out at 50,000-100,000 AU) may have formed near the Gas Giants, but the objects were scattered to the outer solar system later.

Formation of the Asteroid Belt
Asteroids are primordial objects left over from the formation of the Solar System. The prevailing view is that asteroids are leftover rocky matter that never successfully coalesced into a planet. Gravitational interference from Jupiter's huge mass, which tugs on the planetesimal giving them a higher average velocity, prevented protoplanetary bodies from growing larger than about 1,000 km (620 miles). Collisions between these objects, rather than allowing them to coalesce into larger objects, caused them to sometimes shatter, due to their high velocity. Movie.

Theories and Observations go hand in hand
Our understanding of the origin and evolution of the solar system is still very limited. Ideas about how the solar system formed are still not thoroughly tested - there is no single theory that explains it all. Progress is made by cycling through the scientific process of hypothesis, prediction, measurement, theory, hypothesis, etc.