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 46%
   • About 90%, so it ends soon
   • About 4.6%
   • About 100%, so it is nearly done
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 1 hour
   • About 11 hours
   • About 4.6 hours
   • About 23 hours, near the end
3. 3.

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

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

   Hydrogen fusing into helium. Why will the Sun leave the main sequence, by Kira's reading (NASA)?

   • It will grow heavy enough to explode
   • Its fuel will run out, so it will go dark at once
   • It will run out of the oxygen it needs to burn
   • Its core will run out of hydrogen to fuse
5. 5.

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

   • The outer layers cool and shrink
   • The core heats up and the outer layers swell
   • The core explodes as a supernova
   • The whole Sun shrinks and goes completely dark
6. 6.

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

   • It already exploded long ago
   • 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
7. 7.

   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
   • Hotter and dimmer
   • Cooler and redder, though the star is far brighter
   • Hotter and whiter, since the star becomes so much bigger
8. 8.

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

   • They collapse into a black hole around the core
   • They explode in a supernova
   • They stay and keep fusing hydrogen
   • They drift away as a planetary nebula
9. 9.

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

   • Hydrogen into helium
   • Nothing; it glows from stored heat as it cools
   • Carbon into iron
   • Helium into carbon, as in a red giant
10. 10.

    Red giant core fusing helium into carbon, then the white dwarf left behind. Mostly what will the Sun's white dwarf be made of, by Ari's reading (NASA)?

    • Mostly carbon, made by helium fusion
    • Iron, from fusion up the periodic table
    • Mostly hydrogen, as the Sun is now
    • Neutrons packed tightly together