| A | B |
|---|
| photosphere | The layer of the sun that radiates most of the light that reaches Earth is the: |
| magnitude | The measure of a star's brightness: |
| chromosphere | Part of the usn that lies directly above the visible "surface" of the sun |
| hydrogen | The sun's surface is made up mostly of: |
| wind | Streams of electrons and protons that shoot out from the sun's corona make up the solar _____. |
| solar flares | The most explosive events that occur on the sun: |
| cool | Sunspots appear dark because they are relatively _____. |
| auroras | The effect that solar flares have on Earth: |
| helium | The product of nuclear fusion: |
| nuclear fusion | The source of the sun's energy: |
| 5.5 billion years | The sun can continue to exist in its present stable state for about another _____. |
| blue | Stars of this color have the highest surface temperature: |
| red | Stars of this color have the coolest surface temperature: |
| light-years | Stellar distances are usually expressed in what units: |
| temperature & absolute magnitude | A H-R diagram shows the relationsihp between _____ (&) _____. |
| main-sequence | About 90% of stars on the H-R diagram are _____ stars. |
| blue | These main-sequences stars are the most massive: |
| red | These main-sequence stars are the least massive: |
| nebula | Interstellar matter that will eventually form a star: |
| supernova | Massive stars terminate in a briliant explosion called a: |
| collapse | All stars (no matter what size) eventually _____. |
| run out of fuel | Stars collapse because they _____. |
| red giant | A main-sequence star becomes this once when it has exhausted the fuel in its core: |
| main-sequence star | The sun is a ____. (what type of star?) |
| red giant | The next stage in the sun's life cycle: |
| black hole | Light cannot escape the intense gravitational pull of a _____. |
| Milky Way | Our galaxy: |
| within one of the spiral arms | This is where our sun is located in the galaxy: |
| galaxy | Which is biggest--globular cluster, galaxy, star, or planet? |
| nebular | Which of the following is not a type of galaxy: nebular, irregular, spiral, or elliptical? |
| 13.7 | According to the big bang theory, the universe began about ___ billion years ago. |
| born | When a protostar reaches a temperature high enough for nuclear fusion to begin, a star is said to be ____. |
| corona | The outermost layer of the sun: |
