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 90%, so it ends soon
   • About 4.6%
   • About 100%, so it is nearly done
   • 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 11 hours
   • About 23 hours, near the end
   • About 4.6 hours
   • 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?

   • 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
   • Its core will run out of hydrogen to fuse
   • It will run out of the oxygen it needs to burn
5. 5.

   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?

   • Cooler and redder, though the star is far brighter
   • Exactly the same
   • Hotter and dimmer
   • Hotter and whiter, since the star becomes so much bigger
6. 6.

   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 surface is the hottest of any stage
   • Its surface is hotter than the Sun's is now
   • Its huge surface area gives off a lot of light
   • It reflects light from nearby planets
7. 7.

   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 still fusing, but slowly
   • It is tiny, about Earth's size, with little surface
   • Its surface is colder than ice
8. 8.

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

   • They explode in a supernova
   • They collapse into a black hole around the core
   • 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)?

   • Carbon into iron
   • Helium into carbon, as in a red giant
   • Nothing; it glows from stored heat as it cools
   • Hydrogen into helium
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
    • Neutrons packed tightly together
    • Mostly hydrogen, as the Sun is now
    • Iron, from fusion up the periodic table