Recently some of my friends were discussing solar activity, and I learned that there’s a system for rating geomagnetic storms. This recent one was a G3, which is fairly common and not that serious. But about once per month on average there will be a G4 storm which can interfere with GPS navigation and even have the aurora visible as far south as California.
This kind of information and much more is available from a cool web site called Space Weather. For example, did you know that just a week ago an asteroid got as close to the Earth as the moon is? It was just a 27 m in size, so not earth destroying. But these encounters are happening all the time. Browsing around SpaceWeather a bit more and you’ll find great pictures of the sun like this one. Or the current interplanetary magnetic field measured in nanoTeslas.
All in all, fun stuff.