The Sun's life from start to finish

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   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 23 hours, near the end
   • About 1 hour
   • About 11 hours
2. 2.

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

   • 4.6 mm
   • 4.6 m
   • 46 m
   • 0.46 m
3. 3.

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

   • Its fuel will run out, so it will go dark at once
   • Its core will run out of hydrogen to fuse
   • It will grow heavy enough to explode
   • It will run out of the oxygen it needs to burn
4. 4.

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

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

   “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 has too little mass; only far heavier stars explode
   • It will explode once it becomes a red giant
   • It is too hot to explode
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?

   • Cooler and redder, though the star is far brighter
   • Hotter and whiter, since the star becomes so much bigger
   • Hotter and dimmer
   • Exactly the same
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 surface is hotter than the Sun's is now
   • Its surface is the hottest of any stage
   • It reflects light from nearby planets
   • Its huge surface area gives off a lot of light
8. 8.

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

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

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

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