A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction.
Answer:
1. an object that has been intentionally placed into orbit. they are called Artificial Satalites.Satanists.
2. a huge collection of gas ,dust and billions of stars and their solar systems held together by gravity.
3. a large object such as Jupiter or Earth that orbits a star. planets are smaller than stars and they do not produce light.
4. July 16, 1969
Answer:
One AMU or 1 Atomic Mass Unit
