A nebula collapses down into a disk known called:

How long ago did these nebular processes start?

Any object with mass experiences gravity

Which of the following formed when the temperature at the center of the nebula reached 10,000,000 °C and hydrogen fusion began?

These small bodies joined together through collision and force of gravity to make larger bodies called protoplanets.

What is the fuel for the sun's energy?

Planetesimals grew by _______________, the process of adding mass by colliding with other planetesimals.

____________________ were asteroid-like bodies that eventually combined to form planets.

The terrestrial planets are relatively small and rocky. In part, that is because the inner solar system was ____________ during their formation for ice-forming compounds to condense.

As the outer planets grew, their gravity increased, and they were able to capture ____________ and ____________ gas.

Where in our solar system would you expect to find a planet that is mostly made of gas?

During the formation of Earth, small space rocks are attracted to each other by