"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.