The Sun (part 2)
Sunspots are dark areas on the sun. Although they are dark, they are still very hot. They appear dark
due to the fact that they are on a hotter background. The dark center area (umbra) has a temperature
of about 4500K. The less dark outer area (penumbra) is a bit hotter at about 5500K.
As we said before, the Sun spins faster at the equator (25 days) than at the poles (30 days). Combine
this spin differential and the convection going on just under the photosphere dramatically affects the
solar magnetism. As the magnetic line of force are bent due to the spin differential they become
compacted. When they get compacted enough a sunspot is formed. Sunspots come in pairs. Also,
there is usually a pair in the northern hemisphere and pair in the same relative position in the souther
hemisphere. This is called a “set” of sunspots. The pairs of sunspots have opposite polarity. If the
sunspot is on the “edge” of the sun as we view it we can see a prominence. Prominences emerge
from the south pole and re-enter the photosphere at the north pole. Prominences may extend
500,000 km across the Sun’s surface, but prominences this large are rare.
Solar flares are even more energetic than prominences. So energetic, in fact, that the Sun’s gravity is
not great enough to pull the ejected material back to its surface. This material is blasted into space at
incredible velocities and temperatures of 100 million K.
Questions:
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Name a briefly describe (size and temperature) the main regions of the Sun.
What is the diameter of the Sun?
What is the mass of the Sun?
In what region of the Sun does fusion occur?
What “fuel” is being burned in the Sun?
The part of the Sun we see is called the ___.
List the 3 regions of the solar atmosphere.
What are the two most abundant elements in the Sun?
What is the darker region of a sunspot called?
The Sun is a fairly typical star. T or F