That's not what the Batsignal is supposed to look like!

That's not what the Batsignal is supposed to look like!

That's not what the Batsignal is supposed to look like!

Bad Astronomy
The entire universe in blog form
Sept. 23 2012 7:00 AM

That's not what the Batsignal is supposed to look like!

The dark night rises?

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!  

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[Click to stimulatedemissionate.]

Nope. This way cool picture is actually the Very Large Telescope observatory in Chile, though that really is a laser being shot into the sky. Our atmosphere boils and writhes, distorting the view of the stars. There's a layer of sodium atoms in the atmosphere far above the ground, and the laser is designed to make them glow. This creates a very bright point-like source of light that the telescope can view, and measure in real time how the atmosphere is messing up the observation. This can then be compensated using very fast computers and adjustable mirrors, and the result is a far sharper image than could be obtained otherwise.

During this 30 minute exposure, the Earth rotated enough to trail the stars, and the laser was moved to stay on target. That's why the stars are curves, and the normally pencil-thin laser looks like it does. It makes for a pretty slick effect! Shorter exposures are pretty amazing, too, and I have several linked in the Related Posts section below for your amusement.

Image credit: ESO/J. Girard

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