Stars move slowly across the sky over very long periods. The closer a star is, the more easily we can see its movement. Stellar parallax is a shift in a star's apparent position due to Earth's orbit.

Let’s try a demonstration that we all enjoyed in elementary school. Close one eye, hold out your thumb at arm’s length, and align it with an object on the other side of the room. Without moving your ...

Don't miss the big stories. Like us on Facebook. Astronomers quickly become used to dealing with huge numbers. For example, in any one lecture, I might declare that the sun emits some 400 billion ...

Regular readers of my Stargazers columns have surely become accustomed to seeing some pretty big numbers. For example, in any one column, I might explain that our Milky Way galaxy is home to hundreds ...

Exit strategy Artist’s impression of New Horizons as it flew past Pluto in 2015. (Courtesy: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute) NASA’s New Horizons ...