Director of Mumbai’s Nehru Planetarium Arvind Paranjpye shared with us this lovely scarlet image of the sun today. The image shows a very large sunspot dotting the surface of the sun these days. “It is large enough to be seen with naked eyes. However, one should not look at the Sun without proper protection, such as solar goggles used for observing solar eclipses,” he cautions.
For astronomy enthusiasts, the sunspot, cataloged as AR 1967 (Active Region 1967) is 200,000 kilometers in size — big enough to fit in a dozen Earths in itself.
Paranjpye says normally a sunspot’s life is from about a few hours to a few days. Larger ones can live for more than a month. This is one of those. “Actually this spot is the same as seen earlier in the first week of January 2014. It was called AR1944 then.”
The sun rotates on its axis once every month and the sunspot AR1944 that went behind the sun has now reappeared as AR1967.
Sunspots are a result of complex interactions between its magnetic field and rotation. The sun is gaseous body. Unlike solid bodies such as Earth, different regions on the sun take different time to make one rotation. The rotation is fastest close to equatorial region (about 30 days) and slowest near polar region (over 30 days).
Paranjpye further informs that the sunspot appears dark only due to the contrast with surrounding region. The temperature of a sunspot is about 4500 degree Celsius, which is about 2000 degrees lesser than its surroundings.
Sunspots appear in cycles. Sunspots on the surface of the sun go through a cycle of 11 years. “Every five years and six months, we have a very large solar activity that decays over the next five and half years and then increases again. Presently we are close to the end of its current activity cycle.” At the end of the sunspot cycle the magnetic poles of the sun also flip – the North Pole becomes the South Pole and the South Pole becomes the North Pole.
Solar astronomers are closely watching the sun for this event to take place anytime now.
So enjoy the astronomical event but be sure not to forget your goggles.