The Sun's layers and the fusion that powers it
Grade 9 Science Worksheet - Building Confidence
Circle the best answer.
“Star card cutaway of the Sun, not to scale:” On Ari's star card, the Sun's cutaway has four layers lettered A (center) to D (surface). Which layer is the core, where fusion happens?
- A, the center
- C, the layer below the surface
- B, the next layer out from the center
- D, the glowing surface, since it is hottest
Read this first
Star card cutaway of the Sun, not to scale
A, the center; B, the next layer out; C, the layer below the surface, drawn with looping arrows; D, the visible surface.
Which layer of the same cutaway carries energy by hot plasma rising and cooler plasma sinking, by Kira's reading?
- B, the radiative zone
- D, the photosphere
- A, the core
- C, the convection zone
In the Sun's core, hydrogen nuclei join to make helium. What is this process called, by Jun's reading?
- Nuclear fission
- Nuclear fusion
- Melting
- Burning, like a campfire
Which statement describes nuclear fission, by Luz's reading?
- Light nuclei such as hydrogen join into helium
- Atoms change from a solid to a gas
- Fuel combines with oxygen and burns
- A heavy nucleus such as uranium splits into smaller ones
Why is the Sun not a giant fire, by Milo's reading?
- It is a fire; fire and fusion are the same
- It gets its energy from Earth
- Burning needs oxygen; the Sun runs on fusion
- It runs on fission of hydrogen
Star card cutaway of the Sun, not to scale, with an arrow from the center out to the surface. In which order does energy travel out from the Sun's center, by Noah's reading?
- Core → photosphere, straight out in 8 minutes
- Core → convection zone → radiative zone → photosphere
- Core → radiative zone → convection zone → photosphere
- Photosphere → convection zone → radiative zone → core
About how long does light take to reach Earth after it leaves the Sun's photosphere, by Ren's reading?
- About 8 hours
- About 170,000 years
- About 8 minutes
- No time; it arrives instantly
“H-R diagram:” On the star card's H-R diagram, temperature runs from hot on the left to cool on the right. A star at the far left is what, compared with the Sun, by Tala's reading?
- The same temperature as the Sun
- Hotter than the Sun
- Cooler, since left means lower
- Cooler, since it is on the left
The Sun's dot sits at about 5,800 K. Where does a 3,000 K star go on the H-R diagram, by Zee's reading?
- To the left of the Sun
- To the right of the Sun
- Directly above the Sun, since temperature runs up the side
- On top of the Sun's dot
Core, about 15 million °C, hydrogen fuses into helium. The star card's facts box says: "Core, about 15 million °C: hydrogen fuses into helium." What happens in the core, by Esme's reading?
- Hydrogen burns with oxygen
- Hydrogen fuses into helium
- Helium splits into hydrogen
- Nothing; the core is the coolest part