| A | B |
|---|
| nebula | cloud of gas and dust; the birthplace of stars |
| protostar | gas and dust are compressed by gravity and spinning begins; early stage in the life cycle of a star |
| main sequence | stage of a star where hydrogen fuses to create helium |
| giant star | occurs when hydrogen fuel runs out; star expands outward, increasing its size by 1,000 to 10,000 x |
| white dwarf | small, very dense, hot star; mostly made of carbon |
| black dwarf | all energy is used up; the end of the star's life cycle |
| supergiant stars | fuses elements into heavier elements like iron; very rare |
| supernova | giant explosion; occurs when a massive star uses up its fuel |
| neutron star | protons and electrons combine after a supernova; very dense |
| black hole | regions of space where not even light can escape the gravitational pull |
| absolute magnitude | actual brightness of a star |
| apparent magnitude | brightness of a star as seen from Earth |
| lightyear | the distance light travels in one year; equal to 6 trillion miles |
| H-R Diagram | Hertzsprung-Russell Diagram; shows relationships between the temperature of stars and the brightness of stars on a graph |
