Chapter 10 Section 2

A Solar System is born

Our Solar System

• Our solar system consists of 9 (10) planets, the sun and many moons and small bodies (comets, meteors, etc)

The Solar Nebula

• Nebulas are found in the regions of space between the stars.

• Nebulas are mixtures of gas and dust.

• The gasses of nebulas is mostly from Hydrogen and Helium.

Interstellar Medium

• The inter stellar medium, matter of a nebula, is held together by the force of gravity.

• The outward pressure balances with the inner gravitational pull to keep a nebula from collapsing.

Collapsing Nebulas

• The balance between gravity and pressure in a nebula can be upset if two nebulas collide or if a star explodes.

• When a nebula collapses, small areas in the cloud called globules are pushed together.

Collapsing…

• As a solar nebula collapses, the attraction between the particles would grow stronger.

• The center of the collapsed cloud of gas and dust would become very dense and hot.

• The measure of the average kinetic energy in a substance is known as temperature.

• Over time, the nebula will become flattened into a rotating disk

Planetesimals

• In a solar nebula, bits of dust collided and stuck together to form small bodies.

• The largest of these colliding bodies are called planetesimals, or small bodies.

Gas Giants

• The largest planetisimals were far enough away from the solar nebula to attract nebula gases.

• The planets J,S, U , N are called gas giants.

The Sun is born

• When the gas in the nebula’s center stopped collapsing, our Sun was born.

Events in Order

• 1. The solar nebula began to collapse.

• 2. The solar nebula rotates and flattens. It grew warmer near its center.

Events Cont’d

• 3. Planetesimals began to form.

• 4. The largest of the Planetesimals grew in size and attracted more gas and dust.

The end of the events

• 5. Planets began to grow as planetismals collided with one another.

• 6. The sun was born. The remaining gas and dust were removed from the solar system.

Inner Planets

• The inner planets of our solar system are mostly rocky. They are M,V,E,M.

• After the planets were formed, the center mass of the solar nebula became so dense and hot it formed Helium.