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

• nuclear fusion
• gravity
• hydrogen
• iron

Helium is the result of ______ atoms combining in nuclear fusion.

• nuclear fusion
• gravity
• hydrogen
• iron

A star is born and lit up  when ______ happens and provides the star with energy that it will use for millions of years.

• nuclear fusion
• gravity
• hydrogen
• iron

A super giant grows bigger and bigger until it climbs up the periodic table to _____.

• silicon
• oxygen
• hydrogen
• iron

What is this an example of?

• White hole 
• nebula
• protostar
• planetary nebula

What color star lives the longest?

• blue
• red
• yellow
• white

After a supernova of what used to be a blue star with a very large mass, what is left?

• white dwarf star
• black dwarf star
• black hole
• white hole

How are the cores of stars able to stay lit after a planetary nova without having nuclear fusion any more?

• they are very dense and hot
• they are just the star, but smaller
• the light continues to earth, because of the distance
• there is energy that is left over and expands, which makes a new star

What is the most dense type of star?

• brown dwarf star
• neutron star
• white dwarf star
• black dwarf star

The _____ of a star explodes off in a super nova or planetary nebula. 

• core
• stratosphere
• ionosphere
• outer atmosphere