NEBULAR THEORY

Age of the solar system Based on the age of the oldest meteorites and radiometric dating the age of the solar system is calculated to about 4.56 billion years

Two important features FIRST: all the planets orbit in nearly the same flat, disk-like region SECOND: all the planets orbit in the same direction around the Sun These two features are important clues to how the solar system formed.

A Giant Nebula Big cloud of gas and dust Made mostly of hydrogen and helium Contained heavier elements as well Gravity caused the nebula to contract May have come from material leftover from the big bang or from previous supernovas

In the Nebular Hypothesis, a cloud of gas and dust collapsed by gravity begins to spin faster because of angular momentum conservation

The competing forces associated with gravity, gas pressure, and rotation, the contracting nebula begins to flatten into a spinning pancake shape with a bulge at the center.

As the nebula collapses further, instabilities in the collapsing, rotating cloud cause local regions to begin to contract gravitationally. These local regions of condensation will become the Sun and the planets, as well as their moons and other debris in the Solar System.

Formation of the Sun Sun first object to form in the solar system Gravity pulled matter together to the center of the disk Density and pressure increased Nuclear fusion reactions began

Formation of the planets The outer parts of the disk were cooling off Small pieces of dust started clumping together Clumps collided and combined with other clumps Larger clumps attracted smaller clumps with their gravity Eventually, all these pieces grew into the planets and moons that we find in our solar system today

The outer planets Jupiter Saturn Uranus Neptune Condensed from lighter materials such as Hydrogen Helium Water Ammonia Methane It is so cold by Jupiter and beyond that these materials can form solid particles

The inner planets Mercury Venus Earth Mars Formed from denser elements Iron Silicon Magnesium Sulfur Aluminum Calcium Nickel These elements are solid even when close to the Sun

http://Formation of the solar system