Unit 1Planet Formation

A nebula is:

• A cloud of ice
• A cloud of dust and gas
• A cloud of just gas
• A cloud of just dust

The most abundant gases in a nebula are:

• Hydrogen & Oxygen
• Nitrogen & Oxygen
• Hydrogen & Helium
• Oxygen & Helium

A nebula starts to move because:

• A nearby supernova
• A nearby star
• A passing spaceship
• A passing comet

A nebula starts to collapse because of:

• A nearby star shining it's light
• A passing spaceship
• A passing comet
• Gravity

As a nebula collapses it also begins:

• Expand
• Rotate
• Shake
• Turn to ice

A nebula collapses down into a disk known called:

• A compact disk
• An irregular cloud
• An accretion disk
• An circular disk

What forms in the very center of the accretion disk?

• A protosun
• A planet
• A protoplanet
• A planetesimal

What is forming in the accretion disk away from the center?

• Light
• Protostars
• Planetesimals
• Hydrogen

The planetesimals keep:

• Colliding and breaking apart
• Colliding and sticking together
• Colliding and bouncing around
• Breaking down into smaller pieces

The group of inner planets are known as:

• The Terrestrial Planets
• The Gas Giants
• The Outer Planets
• The Hallow Planets