______ is a force that causes dust particles to stick together in a nebula.

• nuclear fusion
• gravity
• hydrogen
• iron

All stars begin as a __________?

• giant
• black hole
• white dwarf
• nebula

Stars are formed in a large cloud of gas and dust called a

• cumulonimbus cloud
• nebula
• neutron star
• black hole

Nebula's are mixtures of gases and what?

• clouds
• stars
• tiny particles
• dust

the planets of the solar system formed as 

• the center of the gas cloud cooled
• planetesimals flattened into a rotating disk
• planetesimals collided into one another
• the sun absorbed extra gas and dust from the solar system

What force acted on the massive nebula to collapse it and eventually form our sun?

• electrostatic force
• strong force
•  weak force
• gravity

A cloud of gas and dust from which bodies in space are formed

• photosphere
• nebula
• solar flare
• Sunspot

Small bodies in the beginning that later became planets

• Planetesimals
• Atom
• Element
• Hypothesis

Spinning on an axis.

• Precession
• Rotates
• Revolves
• Nutation

Orbiting around another body.

• Revolves
• Rotates
• Ellipse
• Planetesimals