My friends and I saw an object that looked like a star moving across the sky. All of a sudden it got very bright and seemed to explode. What was I seeing? Was it a supernova?

Unfortunately what you saw wasn't a supernova explosion! Supernovae visible to the unaided eye have happened only rarely in history, and wouldn't appear to come from a moving star. What you saw in the sky was a satellite. Satellites in orbit look like stars, but they move across the sky, and there are a lot of them visible on any given night. You can see the satellites because sunlight reflects off of their solar panels or communications antennas, and sometimes they will appear to "flare" briefly as sunlight glints off of something on the spacecraft. The global set of Iridium satellites produce especially bright flares that can be the brightest thing in the sky! A good place to find out when satellites are supposed to be visible at your location is Heavens-Above.

This page was last updated July 18, 2015.