Peter Wlasuk informs me this is the second Nova in Sagittarius this summer. Note where the sunspots are located. The one at the lower right is unusually large and has moved rapidly across the Sun. The following is taken from the World Book 2000 edition. Sunspot is a relatively dark area on the surface of the sun.
Sunspots appear dark because they are cooler than the rest of the sun's visible surface.
They may have a temperature of only about l7,000 deg. F, compared with 11,000 deg. Such a large spot consists of a dark central region called the umbra and a lighter surrounding region known as the penumbra. A very small sunspot, known as a pore, has no penumbra. The number of sunspots and solar latitudes at which they appear vary over a period of about 11 years.