The Solar Dynamics Observatory

The Sun is a variable star.

We need to understand solar dynamics for many reasons.

Changes in solar output can affect climate.

Solar storms can fry satellites, endanger astronauts, and cause huge blackouts.

In 1859, there was a HUGE solar flare directed at Earth. For a few minutes, the brightness of the Sun doubled. When the coronal mass ejection reached Earth hours later, auroras were seen as far south as Hawaii and Cuba; telegraph equipment caught fire.

If this were to happen now, it would be catastrophic.

It was a once-in-500-year event, so not very rare...

http://en.wikipedia.org/wiki/Solar_storm_of_1859

http://www.space.com/scienceastronomy/mystery_monday_031027.html

http://www.independent.co.uk/news/science/do-not-adjust-your-sets-solar-storms-could-cause-blackouts-at-olympics-1887630.html