Sunspots

What are sunspots?

• Sunspots are temporary phenomena on the Sun's photosphere that appears visibly as dark spots compared to their surroundings.
• These sunspots can become many times bigger than the Earth.
• Sunspot regions follow the rotation of the Sun; that means a sunspot region travels across the solar disk from east to west as seen from Earth.

Why they are dark?

• Sunspots appear dark to us because they're cooler than the surrounding areas on the sun's visible surface.

Why they occur?

• Sun, unlike Earth and inner planets, does not rotate in one piece, since it is ball of continually circulating hot gases.
• The interior and the exterior of the sun rotate separately.
• The outside rotates more quickly at the equator than at the solar north and south poles.
• Over the time it distorts the sun's magnetic field.
• Thus the regions where twists in the magnetic field lines happens to have so much magnetic power.
• Those regions push back the hot gases beneath them and prevent the heat from rising directly to the surface. In other words, they become sunspots.

Sunspot consists of two parts:

• The dark part (umbra)
• Lighter part around the dark part (penumbra)

When they commonly appear?

• Sunspots are a common sight on our sun during the years around solar maximum.

What is solar maximum?

• Solar maximum or solar max is the period of greatest solar activity in the solar cycle of the Sun, where one solar cycle lasts about 11 years.

Why significant?

• Due to its link to other kinds of solar activity, sunspot occurrence can be used to:
  • Help predict space weather, the state of the ionosphere, and hence the conditions of short-wave radio propagation or satellite communications.

PRELIMS QUESTION

Consider the following statements regarding Sunspots:
1.Sunspots are temporary phenomena on the Sun's photosphere.
2.They're hotter than the surrounding areas on the sun's visible surface.
Which of the statements given above is/are correct?
(a)1 only
(b)2 only
(c)Both 1 and 2
(d)Neither 1 nor 2

Answer to prelims question