We all know the dangers of getting too much sun: things like sunburn and heat stroke can really ruin a summer day. But did you realize that activity on the sun's roiling surface can also cause us a lot of grief? "Sunspots," which look like black holes in the sun's surface, are where bundles of magnetic fields cross the surface of the Sun from the solar interior to the solar atmosphere and back. Hot gas from below bubbles up to the surface (also called the photosphere); the sunspots look dark because they are cooler than their surrounding area. Eruptions from sunspots often shoot X-Rays and high-energy particles our way. Even though the sun is 150 million km (93 million miles) away, solar activity can endanger the International Space Station and the astronauts inside, as well as aircraft flying at high-altitude or high-latitude. X-Rays and high-energy particles can mess up GPS signals and our electrical grid.
Earth has a magnetic field, which begins at the core and stretches far out into space. Typically, this magnetic field is a useful shield for solar activity. However, if the Earth's magnetic field bumps up against the sun's magnetic field, all types of madness can ensue, including geomagnetic storms, or space weather that can affect the International Space Station.
Every time the sun lashes out with another beautiful but potentially threatening solar flare or coronal mass ejection, we are reminded that the naturally occurring solar cycle is approaching a "solar maximum" in 2013 and that solar activity is on the ascent. But what does that mean? If you're having a hard time picturing an active ball of flaming nuclear fusion versus a less-active ball of flaming nuclear fusion, simply see above.
