The Earth has music for those who listen. So does one of Earth’s finest phenomena: the aurora. (Also known as the northern lights and aurora borealis in the Northern Hemisphere—or the southern lights and aurora australis in the Southern Hemisphere.) Pictured here are the northern lights, captured by astronaut Don Pettit aboard the ISS, as they danced across Earth’s atmosphere. This electric tango happens when charged particles from the Sun move through Earth’s magnetic field and collide with atoms in the upper atmosphere. Depending on which gas is most excited to waltz, different colors will appear. High-energy electrons cause oxygen to emit green light, while low-energy ones emit red. Nitrogen invites in blue light, and the three often blend together to create an array of pinks, purples, and whites. Image description: A prominently green aurora streaks through Earth’s atmosphere. The aurora covers most of the image on the right, and above it, streaks of red are visible. One of...