Active Region AR1678 has quickly formed into a region larger than three Earths.
This view shows the formation of this region from February 17 through part of February 19, 2013.
Sunspots usually show up as small forms that are irregularly shaped, and grow within days or weeks to their full size. While they can last weeks or months, they do eventually disappear, often by breaking into smaller and smaller sunspots.
Sunspots are a magnetic phenomenon on the Sun. You can think of them as small pores on the surface of the Sun where lines of magnetic force enter and exit.
Sunspots always come in pairs like the north and south poles on a bar magnet. The strength of the sunspot magnetic fields are usually 1000 times as strong as the average solar magnetic field. Because magnetic fields can produce pressure, inside sunspots, the gas does not need to exert quite as much pressure as elsewhere on the Sun to insure that the total pressure across a sunspot is in equilibrium with the gas surrounding the sunspot.
Since the cooler a gas is, the less pressure it exerts, this means that the gas inside a sunspot can be cooler than the gas in the rest of the solar surface and still, with the help of the sunspots magnetic field, remain in equilibrium.
Credit: NASA SDO
