Extrasolar Planets & SETI, Page 3: [Previous Page] [Next Page] [Syllabus] Textbook pages 228 - 234

Formation of our Solar System

From the characteristics we see in our Solar System, scientists have put together a scenario for how our Solar System came to be. MOVIEMOVIE2

Everything (Sun, planets, asteroids, comets) were created about 4.5 b.y.a. The material making up the Solar System all came from a single mostly homogeneous cloud of material. The matter rotated in a flattened plane, splayed out in a disk due to the angular momentum. With time, material not falling to the central Sun would either be thrown out of the system or begin to collect and build up planetesimals. At safe relative distances, planetesimals built up to form the planets.

If all the planets formed from the same material, why are they so different? Differing distances (temperatures) from the Sun allowed for the differing chemistries that would go into making the planets. Planets near by were formed in much higher temperatures, boiling off their lighter elements (H, He), and leaving behind rocks of metals and silicates. Very distant planets were formed in such a cold environment to have formed water, ammonia and methane ices (like the distant comets).