Tonight's full moon is the first of two full moons in May, a rare occurrence. One might say, "once in a blue moon." ...

Among the strangest ideas in planetary science is the Double Moon Theory—the belief that Earth once had two moons. This video explores how the theory developed, what evidence supporters point to, and ...

Ever wonder why we say 'once in a blue moon'? May’s full moon schedule sheds some light. This Sky Above includes Halley's ...

The sky will be graced with the flower moon on Friday and a blue moon on May 31 — two full moons in one month.

A video filmed in Taylor, Michigan, showing what appear to be two moons in the night sky has prompted widespread curiosity — but as interesting as it could have turned out if true, astronomers say the ...