Our sun operates on an 11-year cycle of activity--at the nadir, it's relatively quiet, with a small number of sunspots and fewer flares and coronal mass ejections or CMEs. CMEs are explosions of massive quantities of matter from the Sun moving around the speed of the solar wind. At the height of the solar cycle, more sunspots appear on the sun's surface and it's more active. And yes, there are more flares and CMEs. Instead of one or two CMEs a week, at the peak of the cycle, there can be three or more CMEs a day.
For the most part, these balls of super-heated gas a particles miss the Earth entirely. But, when a large mass hits the Earth and its orientation aligns with the magnetic field of the planet, bad things can happen. In 1859, a geomagnetic storm delivered such a shock to our atmosphere that it shocked operators and ignited fires in a couple of telegraph offices. A similar storm took out power for a few million people in Quebec in 1989.
We have directly measured data on solar activity for a few hundred years, but we really have no idea how strong solar storms can be. Because of that, and because we rely on the electrical grid for so much in developed nations, Mike Hapgood, a solar weather expert from the UK, wants us to take solar storms seriously--developing better tools to help us better predict solar weather, as well as hardening our electrical grid to prevent permanent, lasting damage to our infrastructure caused by geomagnetic storms.
Oh, one last thing. The Sun is will reach the peak of its 11-year solar cycle in 2014. We've already had one near miss this year, and it's only going to get more exciting from here, at least until we start edging toward the low point of the solar cycle again.