(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.)

(THE CONVERSATION) During the early hours of Jan. 31, there will be a full moon, a total lunar eclipse, a blue moon and a supermoon – all at the same time. None of these things is really all that unusual by itself. What is rare is that they’re happening all together on one day.

What makes the moon look full?Like the Earth, half the moon is illuminated by the sun at any one time. The moon orbits around the Earth and as a result we see different amounts of the lit-up side.

A full moo...