Subscribe to our newsletter. A dark patch in the sun's photosphere resulting from a localised fall in temperature to about 4000 K. Most spots have a central very dark umbra surrounded by a lighter penumbra.
Sunspots tend to occur in clusters and to last about two weeks.
The cause is thought to be the presence of intense localised magnetic fields, which suppress the convection currents that bring hot gases to the photosphere. They offer to buy or sell new and used college textbooks. Branson ultrasonic cleaners - buy on line Buy Bransonic table top ultrasonic cleaners on line. Ideal for jewelry, pipettes, dental instruments, and small components. Links to industrial ultrasonic sites.