Bad Astronomy

Jupiter rolls into view

If you go outside a couple of hours after sunset tonight and look east, you’ll see a very bright “star” in the sky. That’s Jupiter.

If you look at it with a nice telescope equipped with a good camera and filter set, and you have the patience to spend a bit of time afterwards putting the images together into a brief animation, you’ll see this:

Cool, eh? [Make sure you set it to higher resolution to get the full effect.] That was done by Dutch “amateur” astronomer Henk Mannetje Emil Kraaikamp. Jupiter appears to roll across the screen because he aligned all the images on the clouds you can see on the planet; keep your eyes on the Great Red Spot, for example, and you’ll see it doesn’t move inside the frame. So as Jupiter’s rapid rotation (once every ten hours or so) makes it spin visibly even over the time of these observations, which in turn makes it look like it’s rolling.


The dot on the right is the moon Europa, which orbits Jupiter every three and a half days. Its orbital motion relative to Jupiter appears to make it move to the right as Jupiter moves left, and it disappears out of the telescope’s field of view.

My favorite thing is how three dimensional Jupiter looks! The rotation, coupled with how it gets darker near its edge, really gives you the sense that you’re seeing a massive planet spinning. Which, of course, you are.

Jupiter’s moons and even some of its clouds can be seen using binoculars, so if you get a chance, go outside and take a look!

Tip o’ the Equatorial Belt to theritz.

Related posts:

- Jupiter, the Bringer of Jollity
- Juno on its way to Jupiter!
- Home, from the start of a long, long journey
- Astronomers thankful for return of Jupiter’s belt