The Sun's life from start to finish

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   The Sun is 4.6 billion years into a 10-billion-year main sequence. About what percent has it used, by Bo's math?

   • About 4.6%
   • About 100%, so it is nearly done
   • About 90%, so it ends soon
   • About 46%
2. 2.

   If the Sun's 10-billion-year main sequence were one 24-hour day, about how many hours would have passed so far, by Esme's math?

   • About 4.6 hours
   • About 11 hours
   • About 23 hours, near the end
   • About 1 hour
3. 3.

   On Jun's timeline, 1 m stands for 1 billion years. How far from the Sun's formation is now?

   • 0.46 m
   • 4.6 mm
   • 4.6 m
   • 46 m
4. 4.

   “Star card cutaway:” When the core runs out of hydrogen, gravity squeezes it. What happens next, by Luz's reading (NASA)?

   • The core explodes as a supernova
   • The whole Sun shrinks and goes completely dark
   • The core heats up and the outer layers swell
   • The outer layers cool and shrink
5. 5.

   “sources give 7 to 10” Why will the Sun not end as a supernova, by Milo's reading (NASA)?

   • It will explode once it becomes a red giant
   • It has too little mass; only far heavier stars explode
   • It is too hot to explode
   • It already exploded long ago
6. 6.

   The Sun today beside a red giant, with surface colors shown. Compared with the Sun today, how does a red giant's surface compare, by Noah's reading?

   • Exactly the same
   • Cooler and redder, though the star is far brighter
   • Hotter and whiter, since the star becomes so much bigger
   • Hotter and dimmer
7. 7.

   Drawing of a huge red giant beside a small yellow star. Why is a red giant so bright if its surface is cool, by Pia's reading?

   • Its huge surface area gives off a lot of light
   • Its surface is the hottest of any stage
   • It reflects light from nearby planets
   • Its surface is hotter than the Sun's is now
8. 8.

   A young white dwarf has a hotter surface than the Sun today but is far dimmer. Why, by Ren's reading?

   • It fuses hydrogen at its surface
   • It is tiny, about Earth's size, with little surface
   • It is still fusing, but slowly
   • Its surface is colder than ice
9. 9.

   What becomes of the Sun's outer layers at the end of its red giant stage, by Tala's reading (NASA)?

   • They drift away as a planetary nebula
   • They collapse into a black hole around the core
   • They stay and keep fusing hydrogen
   • They explode in a supernova
10. 10.

    Star card cutaway of a white dwarf. What fuses inside a white dwarf, by Zee's reading (NASA)?

    • Hydrogen into helium
    • Carbon into iron
    • Helium into carbon, as in a red giant
    • Nothing; it glows from stored heat as it cools