Comet Pan-STARRS Visits an Iconic Galaxy

Bad Astronomy
The entire universe in blog form
April 3 2013 2:05 PM

The Comet and the Galaxy

Never say never, especially when it comes to posting comet pictures.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

Here is another shot of the beauty that is comet C/2011 L4 (Pan-STARRS), taken in late March as it passed the iconic Andromeda galaxy:

Comet and galaxy
Comet Pan-STARRS passes the Andromeda galaxy. Click to embiggen, and you really, really want to.

Image credit: Smilyk Pavel, used by permission.

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This stunning picture was taken by Smilyk Pavel, an astrophotographer, about 60 kilometers from Syktyvkar, the capital city of the Komi Republic in Russia. It’s a stack of 12 separate pictures, each two minutes long.

The comet was about 180 million kilometers (110 million miles) away from Earth when this picture was taken. For comparison, the Andromeda galaxy is roughly 25 million trillion kilometers away. Amazingly, they appear to be the same size in the sky, but that’s a massive, massive illusion due to perspective. The Andromeda galaxy is, well, a galaxy. Those tend to be big, and far away.

I love the scale of this. Andromeda is far larger than the full Moon on the sky, so what you’re seeing here is a pretty big chunk of sky, roughly the size of your palm held at arm’s length. And the comet sure looks different now than in earlier pictures; we’re seeing the tail from a different angle, so it looks more spread out and fan-shaped than earlier (though I'll note that the comet is smeared out a bit due to its motion compared to the background stars).

If you want to see this for yourself, tonight’s not a bad time to try. The comet and galaxy are still relatively close to each other in the sky, but since the comet’s on the move that won’t last long. Sky and Telescope has a how-to on viewing. The farther north you are, the better, and you’ll need binoculars no matter what. It may be tough, since the two are low to the northwest after sunset, when the sky is still bright, but it’s definitely worth a shot. It’s not something you get to see very often!

If you want to see more pictures of this amazing comet, I have posted pictures in previous posts: here, here, here, here, here, and here. My thanks to my friends at APOD for helping me track this down; they posted the image earlier today.