Going outside to gaze at the stars is a lot of fun, even if you're a beginner. If you have some experience you can identify constellations, planets, individual stars, and more.
One thing I love is a surprise: The flash of a meteor zipping across the sky, or happening to see a faint satellite moving amongst the stars.
Satellites are predictable, though. The science of orbital mechanics means being able to convert the physical parameters of an orbit (the radius, period, ellipticity, and so on) into coordinates on the sky for a given time. There are plenty of apps out there that do this for you; put in your position on the Earth and a time, and it will tell you what satellites are up and when.
Research scientist and amateur astronomer Thomas Glenn did this recently, but he was trying to do more than just spot a satellite: He wanted to capture the International Space Station (ISS) passing directly in front of Mars!
This is called a transit. Seeing the ISS pass in front of the Moon or Sun is hard enough, and they're 100 times wider than Mars. That means the path on the ground where the ISS ...