STEREO sees lunar transit
The NASA spacecraft STEREO-B caught this transit of the moon across the sun in 2007. NASA's STEREO mission consists of two spacecrafts launched to study solar storms. Solar storms are responsible for the magnificent beauty of aurora borealis on Earth, but they can also cause satellite failures, power blackouts and pipeline explosions. As experts note, solar storms occur when an eruption on the surface of the sun sends radiation or electrically charged particles toward Earth. They can release the equivalent energy of 1 billion hydrogen bombs.