Expanding Crab Nebula

29 March 2019

I was talking with a mate the other day about these Facebook posts, when I casually mentioned the one I'd done about the expanding Crab Nebula.  Duh, turns out I'd never posted it! So here it is.


The Crab Nebula (M1) was formed by a supernova in 1054, so a little under 1000 years ago. People saw it from the Earth. Supernovas are big bangs.

The gas and dust ejected from the exploding star formed a massive nebula with criss-crossing shock waves further interacting with clouds of hydrogen, oxygen and other gases and elements. It's a very complex nebula - a little like the Tarantula.

But the real point is that it's still expanding. So fast, in fact, that you can actually see it growing in a time-lapse taken by Detlef Hartmann over a ten-year period.

I would definitely recommend having a look at the Crab Nebula - it won't move while you're watching it, of course, even though it is expanding at about 1000 km per second. It's smallish and pretty faint, so to see it, you'll need a pretty long focal length telescope, preferably with a good wide aperture. 

A Schmidt-Cassegrain would be nice to use, something like a 9.25" Celestron. It'll need the CGX equatorial mount if you're going to photograph it, or a CPC fork mount if you're just watching.

But you know, a large Dobsonian would be a fantastic way of seeing it yourself, albeit a bit smaller. And you can get a whole lot more aperture without having to shell out your hard-earned.

You'd be doing a whole lot better than me. Not only have I not photographed it, I don't think I've even seen it. From Melbourne, where I live, or even Central Victoria, where I do most of my imaging, the Crab Nebula never gets above 20 degrees above the northern horizon. Its best time is right in the new year, when it transits at midnight.