Stars and Brightness — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. Stars first form inside a giant cloud of gas and dust called a nebula.
Gravity pulls gas and dust together inside a nebula until a new star ignites.
2. After leaving the nebula, a steady star spends most of its life on the main sequence.
Main sequence stars, like our Sun, fuse hydrogen for billions of years in stable balance.
3. When a medium star runs low on hydrogen, it swells into a red giant.
Reduced fuel causes the core to contract while outer layers expand into a red giant.
4. After shedding its outer layers, a medium star leaves behind a hot, dense core called a white dwarf.
A white dwarf is the cooling remnant left after a medium star sheds its outer shell.
5. Massive stars end their lives in a powerful explosion called a supernova.
When a massive star runs out of fuel, its core collapses and triggers a supernova explosion.
6. The most massive star cores can collapse into objects with such strong gravity that even light cannot escape, called black holes.
When a very massive core collapses, it forms a black hole whose gravity traps all light.
7. A huge group of billions of stars held together by gravity is called a galaxy.
A galaxy is a vast collection of stars, gas, dust, and dark matter bound by gravity.
8. Light from the Sun reaches Earth in about eight minutes.
Sunlight travels roughly 93 million miles to Earth in about eight minutes.
9. The closest star beyond the Sun, Proxima Centauri, lies about four light-years away.
Proxima Centauri sits about 4.2 light-years from Earth, making it our nearest stellar neighbor.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Hubble Space Telescope
→ Orbits Earth and views visible and ultraviolet light from above the atmosphere
Orbits Earth and views visible and ultraviolet light from above the atmosphere
James Webb Space Telescope
→ Orbits far from Earth and captures infrared light to see distant, early galaxies
Orbits far from Earth and captures infrared light to see distant, early galaxies
Ground-based optical telescope
→ Sits on a mountain and views visible light, weather permitting, from the ground
Sits on a mountain and views visible light, weather permitting, from the ground
Radio telescope
→ Uses a large dish to collect radio waves from space objects like pulsars
Uses a large dish to collect radio waves from space objects like pulsars
Different telescopes specialize in different wavelengths and locations to study a wide range of cosmic objects.