Mars is usually a long ways away: up to 250 million miles, in fact. But it can also get much closer, the distance varying according to its orbit.
On May 30, according to NASA, that distance will be its closest in 11 years, or nearly 47 million miles. That's because both planets will be in rough alignment on the same side of the sun.
Mars' orbit around the sun takes 687 days, meaning that Earth and Mars fly by each other around once every two years. But because their orbits are shaped differently, Mars is sometimes closer and sometimes farther.
The closeness this year, at any rate, is good news for stargazers, since if you look up at night in the right place, you should be able to spot the Red Planet with the naked eye.
It's also good news for NASA, which used the Hubble Space Telescope to snap some new photos of the planet.
This century so far has seen a few close Mars encounters, including, in 2005, when the planet came as near to Earth as it had in 60,000 years: a mere 34.6 million miles. It will next come that close in 2287.