The Sun Flashcards
What is the diameter of the Sun?
1.4 million km
100 times the diameter of the Earth (13,000 km)
What is the average distance from the Earth to the Sun?
150 million km
What is the composition of the Sun?
- Hydrogen 75%
- Helium 25%
- Traces of other elements
Describe the Sun’s surface.
- Photosphere
Visible surface
5800 K
Describe the Sun’s atmosphere.
-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.
Describe the Proton-Proton Chain.
Proton-Proton Chain reaction at Sun’s core.
Only hot enough in the core (15 million K)
How is energy released from this reaction?
At each stage in the Proton-Proton chain, matter is lost
E = mc2
Describe 2 methods that we can use to observe the sun.
- Project an image of the sun onto paper.
- Use a special H-Alpha or Mylar filter on a telescope.
What is a sunspot?
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.
Describe the structure of a sunspot.
- Umbra: 2000 k cooler than rest of sun (3,800 K)
- Penumbra: 200 K cooler than the photosphere (5,600 K)
Describe the rotation of the Sun.
The Sun doesn’t rotate as a solid body:
The equator takes 25 days to rotate.
The poles take 36 days to rotate.
What is the solar cycle?
The relative number of sunspots follows a regular 11 year pattern called the Solar cycle
What is a Butterfly diagram?
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.
What is the solar wind?
A steady stream of charged particles from the corona:
- Mostly Electrons and Protons
- Some Helium Ions
Describe the two types of Solar wind?
-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.
