Blue moon

A rare seasonal "blue moon" will take place on May 18. The next one won't be until August 2021.

There are two definitions of "blue moon." Neither involve the moon actually turning blue.

It's also the best time of the year to see Mercury.

The U.S. won't see another super blue blood trio until 2037.

The lunar eclipse can help scientists learn how to spot "biosignatures" on distant planets.

The moon will glow big, bright—and red.

Three separate lunar events will coincide next week.

The second supermoon of the month will glow a spectacular red.

The combination of lunar eclipse, supermoon and blue moon is incredibly rare.

This moon has piled up a stunning array of adjectives—here's what they all mean.

"The elements of this case are odd, at best."

It turns out that tonight's lunar event has nothing to do with color.