When Was the Last Time All the Planets Aligned?

Erik: It kind of depends on your definition of aligned. Like if you think they’re going to be in a straight line in the solar system, for the 3 inner planets, that actually happens like every 40 years. But for all 8, calculations seem to be about every 400 billion years. So which means it has never, ever happened. But we do get every so often these things called planetary parades. And those happen pretty often. The term planetary parade is cute, but it also is more accurate in the sense that it does describe what you actually see in the sky, with the planets being in a nice straight line. There will be a planetary parade on August 12th, so there’s going to be 6 planets in the sky. Unfortunately, 2 of them are going to be Uranus and Neptune, so you won’t be able to see them, but the planets will be in a nice straight line spread across the sky.

Off camera: If all the planets are in a marching band, because they’re in a parade, what instrument do you think each planet would play?

Erik: Oh, gosh. Mercury would be a piccolo. Venus would be a trumpet. Mars, you know, maybe mysterious like a theremin. Jupiter, I’m going to give double bass. Saturn, a… uh… A harp, so.