What process marks the birth of a star?
when it begins combining hydrogen to form helium
when its mass expands and cools
a supernova explosion
when gravity pulls in nebular dust
1 answer
When gravity pulls in nebular dust
when it begins combining hydrogen to form helium
when its mass expands and cools
a supernova explosion
when gravity pulls in nebular dust
1 answer
1 answer
22 answers
1 answer
11 answers