Super blood Moon

22 February 2019

Last Tuesday was a full Moon. Big deal, it happens every month. But it was also a super Moon. Apart from a comic hero, what is a super Moon?

The Moon orbits the Earth. Seen from above, it's as though the Earth and Moon are doing a dance. Imagine a pair of ice skaters, one large and one small, spinning while holding hands.

But the Moon's orbit is "eccentric". It's not a circle, but an oval, with the Earth slightly to one end. So the Moon gets closer and further away from the Earth as it goes around. So now imagine our two ice skaters not holding hands, but joined by a spring that expands and contracts. Sometimes the skaters are further away from each other, so they'll look smaller to each other. Sometimes they're close, so they'll appear larger to each other.

Now imagine there’s a spotlight on our skaters, shining from the side. As the skaters spin around, sometimes the spotlight illuminates one skater’s face, and sometimes it illuminates the side of their heads. Somewhat strangely, this spotlight is in a lift, and it moves up and down, sometimes shining from above, sometimes shining from the floor level.

Yeah, I’m getting there, there's a lot going on here.

If the spotlight illuminates the whole face of one skater at the same time as the spring is at its shortest, this is the equivalent of the super Moon. The second skater sees a big close, fully lit face.

If all that happens when the spotlight is at floor level, and the fully lit face gets shadowed - just for a second - by the other skater's head, it's a lunar eclipse as well. Yes, it's our super blood Moon.

So...

Sometimes we get full Moons, sometimes we get super Moons, sometimes we get blood Moons, and just occasionally we get super blood moons.

So a full Moon is, well, usual.

Add the Moon being closest to the Earth: a super Moon.

Add a lunar eclipse: a super blood Moon.

Now, can someone explain a "super blood wolf Moon"?

There's an animation of this here.