Solar Max | Universe Today

Written by Fraser Cain

The number of sunspots on the Sun rise and fall over the course of an 11-year cycle. At the low point, the solar minimum, there are very few sunspots on the Sun, and little solar activity. And then at the high point of this cycle, the solar maximum, or solar max, there are more sunspots and the Sun is highly active.

The Sun atmosphere is structured by its magnetic field. These field lines rise up from inside the Sun and pierce through the photosphere – the visible surface of the Sun. Sun spots appear in the points where the field lines go through the photosphere, and they appear in pairs as the magnetic lines form loops. When the solar activity reaches its maximum, there are more sunspots on its surface, and more prominences and coronal mass ejections.

The sunspot cycle was first discovered in 1843 by Samuel Heinrich Schwabe, who noticed a periodic cycle in the number of sunspots visible on the surface of the Sun. Since sunspot observations first began in 1699, there have been 29 cycles, with an average length of 10.66 years. The next solar max is expected to begin in 2012.

We've written several articles for Universe Today about the Sun. Here's an article about the source of the Sun's solar wind, and here's an article about how we might harvest solar power from space.

If you'd like more info on the Sun, check out NASA's World Book on the Sun, and here's a link to NASA's SOHO mission webpage.

We've also recorded several episodes of Astronomy Cast about the Sun. Listen here, Episode 30: The Sun, Spots and All.

Filed under: Astronomy