The Sun's layers and the fusion that powers it

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Power about 3.8 × 10^26 W; c² ≈ 9.0 × 10^16 m²/s². The Sun gives off about 3.8 × 10^26 W (IAU). With E = mc² and c² ≈ 9.0 × 10^16 m²/s², about how much mass becomes energy each second, by Esme's math?

   • About 4 kilograms
   • Zero, since mass is conserved
   • About 4 billion metric tons
   • About 4 million metric tons
2. 2.

   Fusion turns about 0.7% of hydrogen's mass into energy. If 1 kg of hydrogen fuses into helium, about how much mass becomes energy, by Jun's math?

   • 0 g, since mass is conserved
   • About 7 g
   • About 0.7 g
   • About 70 g
3. 3.

   Why does the Sun become very slightly less massive over time, by Kira's reading?

   • Fusion turns some of its mass into energy that leaves as light
   • Fission splits off pieces of the Sun
   • It does not; its mass stays exactly the same
   • It burns and loses smoke into space
4. 4.

   Luz's friend says the Sun is a giant ball of burning gas, like a campfire. Which response is best?

   • Disagree: the Sun runs on fission of uranium
   • Agree: the Sun burns hydrogen with oxygen
   • Disagree: its energy comes from nuclear fusion in the core
   • Agree: fire and fusion are the same process
5. 5.

   Noah's friend says the Sun's surface must be its hottest part, since that is where the light comes from. Which response is best?

   • Agree: the core is cold and dark
   • Agree: light comes from the hottest part
   • Disagree: the 15 million °C core is far hotter
   • Disagree: the convection zone is the hottest part

6. Read this first

   Sun temperatures (NASA)

   Layer	Temperature
   core	about 15 million °C
   photosphere	about 5,500 °C

7. 6.

   Using kelvins (°C + 273), about how many times hotter is the Sun's core (15 million °C) than its photosphere (5,500 °C), by Pia's math?

   • The photosphere is the hotter one
   • About 2,600 times
   • About 3 times
   • About 2,700 times
8. 7.

   NASA lists the photosphere at about 5,500 °C and the corona, the Sun's outer atmosphere, at up to 2 million °C. Which statement is true, by Ren's reading?

   • The corona is where fusion happens
   • The corona is far hotter than the photosphere
   • The photosphere is the hottest layer outside the core
   • The corona is cooler, since it is farther from the core

9. Sun surface temperature

   Source	Value
   H-R card	about 5,800 K
   NASA	about 5,500 °C

10. 8.

    The H-R card puts the Sun at about 5,800 K, and NASA lists its surface at about 5,500 °C. Do they agree, by Tala's math?

    • No: 5,800 K must be the core temperature
    • Yes: kelvins and degrees Celsius are the same numbers
    • No: they differ by 300 degrees
    • Yes: 5,500 + 273 is about 5,800 K
11. 9.

    Why does fusion need the core's temperature of about 15 million °C, by Zee's reading?

    • Positive nuclei repel; only very fast ones get close enough to fuse
    • Heat splits helium back into hydrogen
    • Heat lights the hydrogen, as a match lights wood
    • Fusion needs oxygen, which only the core has
12. 10.

    What keeps the Sun from collapsing under its own gravity, by Bo's reading (NASA)?

    • Outward pressure from fusion-heated gas balances gravity
    • Fission blasts push it apart
    • Burning gases push outward like exhaust from a rocket engine
    • Nothing; the Sun is collapsing quickly