The Sun's life from start to finish
Grade 9 Science Worksheet - Building Confidence

Circle the best answer.
Timeline ruler of the Sun's life with a dot at now. The Sun is now fusing hydrogen into helium in its core. Which stage of life is it in, by Ari's reading?
- Protostar
- White dwarf
- Red giant
- Main sequence
Drawing of the Sun swelling into a large red star. Late in its life, the Sun will swell to hundreds of times its size and glow red. What is this stage called, by Bo's reading?
- Red giant
- Supernova
- White dwarf
- Main sequence
The Sun's last stage is a hot core about the size of Earth that slowly cools. What is it called, by Kira's reading?
- A black hole
- White dwarf
- A small star still fusing hydrogen
- A neutron star left by a supernova
What comes right after the main sequence for the Sun, by Luz's reading?
Timeline ruler with the main sequence shaded and the next stage blank. Timeline ruler with the main sequence shaded and the next stage blank. main sequence - It swells into a red giant
- It shrinks straight to a white dwarf
- It goes dark at once
- It explodes as a supernova
What happens right before the Sun becomes a white dwarf, by Milo's reading?
Timeline ruler with the white dwarf stage marked and the stage before it blank. Timeline ruler with the white dwarf stage marked and the stage before it blank. Timeline ruler white dwarf stage - The main sequence begins
- A supernova blast
- A protostar forms
- Its outer layers drift away as a planetary nebula
About how long is the Sun's main-sequence stage, by Pia's reading (NASA)?
Timeline ruler from 0 to 12 billion years with the main sequence shaded from 0 to 10. Timeline ruler from 0 to 12 billion years with the main sequence shaded from 0 to 10. Timeline ruler, billion years main sequence 0 1 2 3 4 5 6 7 8 9 10 11 12 0 - About 10,000 years
- About 4.6 billion years, ending now
- About 100 years
- About 10 billion years
About how much main-sequence time does the Sun have left, by Ren's reading?
Timeline ruler: now at 4.6 billion years; main sequence ends at about 10. Timeline ruler: now at 4.6 billion years; main sequence ends at about 10. Timeline ruler: billion years 0 1 2 3 4 5 6 7 8 9 10 4.6 10 4.6: now at 4.6 billion years 10: main sequence ends at about 10 - About 10 billion years more
- It ends within the next century
- About 5 billion years
- About 50 years
Star card cutaway of a red giant with its core marked. What does the core of a red giant like the future Sun fuse, by Tala's reading (NASA)?
- Hydrogen into helium, just as now
- Nothing; fusion has stopped for good
- Iron into gold
- Helium into carbon
Why does a white dwarf glow, by Zee's reading (NASA)?
Drawing of a white dwarf with heat arrows leaving it. Drawing of a white dwarf with heat arrows leaving it. white dwarf heat - It is still hot and slowly cools; no fusion happens
- It reflects light from other stars
- It fuses helium in its core
- It fuses hydrogen like the Sun today
About how big is a white dwarf, by Esme's reading (NASA)?
Size bars, not to scale: Earth, the Sun and a white dwarf. Size bars, not to scale: Earth, the Sun and a white dwarf. Size bars 0 0.2 0.4 0.6 0.8 1 Earth 1 the Sun 1 a white dwarf 1 Not to scale. - About 20 km across, like a neutron star
- The same size as the Sun now
- Hundreds of times the Sun's size
- Roughly the size of Earth