As it approaches the peak of its 11-year cycle of activity, the Sun is putting on a magnificent display of sunspots on its surface. The maximum activity is expected in the middle of next year.
Observers say that the current series of sunspots is particularly fine.
Each spot is about the size of the Earth. They appear dark only by contrast. The normal temperature on the Sun's surface is 6,000 degrees Celsius. A sunspot is at a temperature of about 3,000 degC. If it were on its own it would be brighter than an arc lamp. Sunspots are caused when magnetic fields, coiled in the shape of a tube, which emerge from below the Sun's visible surface.