1. What is the diameter of the Sun?
show answer
– 1.4 million km
– 100 times the diameter of the Earth (13,000 km)
2. What is the average distance from the Earth to the Sun?
3. What is the composition of the Sun?
show answer
– Hydrogen 75%
– Helium 25%
– Traces of other elements
4. Describe the Sun’s surface.
5. Describe the Sun’s atmosphere.
show answer
– Thin Chromosphere (Sphere of Colour)
- 2000 km thick.
- Not visible unless during an eclipse.
-Extensive Corona (Crown).
- Also visible during an eclipse.
- Ionised gas 2 million Kelvin.
- Hot enough to emit X- rays.
6. Describe the Proton-Proton Chain.
show answer
– Proton-Proton Chain reaction at Sun’s core.
- Only hot enough in the core (15 million K)
– Proton + Proton = Hydrogen-2 + Neutrino + Positron.
Hydrogen -2 + Proton = Helium-3
Helium -3 + Helium-3 = Helium-4 + Proton + Proton
7. How is energy released from this reaction?
show answer
– At each stage in the Proton-Proton chain, matter is lost
- E = mc2
- Released energy :
- Keeps core hot for further Nuclear Fusion
- Convected to photosphere and then radiated into space.
8. Describe 2 methods that we can use to observe the sun.
show answer
– Project an image of the sun onto paper.
– Use a special H-Alpha or Mylar filter on a telescope.
-Remember, NEVER look at the sun directly as this can easily cause permanent blindness!
9. What is a sunspot?
show answer
Cooler regions on the surface (Photosphere) of the Sun.
- Correspond to strong local magnetic fields.
- Inhibit upward convection of solar material from the core below.
- Occur in pairs.
10. Describe the structure of a sunspot.
show answer
– Umbra.
- 2000 k cooler than rest of sun (3,800 K)
– Penumbra.
- 200 K cooler than the photosphere (5,600 K)
11. Describe the rotation of the Sun.
show answer
– The Sun doesn’t rotate as a solid body.
- The equator takes 25 days to rotate.
- The poles take 36 days to rotate.
12. What is the solar cycle?
show answer
– The relative number of sunspots follows a regular 11 year pattern called the Solar cycle.
13. What is a Butterfly diagram?
show answer
– A Butterfly diagram is a graph of the latitude of the spot on the sun’s surface.
- At the beginning of a solar cycle there are a few sunspots at 35 to 40 degrees north and south.
- As the solar cycle progresses, there are more spots but their positions drift towards the equator.
14. What is the solar wind?
show answer
– A steady stream of charged particles from the corona.
- Mostly Electrons and Protons
- Some Helium Ions
15. Describe the two types of Solar wind?
show answer
- Slow (400km/s)
- Fast (850km/s)
- Fast originates from coronal holes at the poles.
- Magnetic field lines here are open so particles can escape the sun more easily.
16. What is H-Alpha light?
show answer
– This is EMR emitted by ionised Hydrogen Gas
- 656nm wavelength
- Used to observe the sun and emission nebulae.
17. What other wavelengths of EMR are used to study the Sun?
18. What features of the Sun can you observe using an H-Alpha filter?
show answer
- Solar prominences
- Large clouds of cooler gas in the Sun’s atmosphere
- Solar filaments
- Cooler gas silhouetted against hotter photosphere.
- Solar flares
- Sudden releases of energy
- Sunspots
- Chromosphere
