Straighten the Horizon in Photoshop

How do you quickly and easily straighten the horizon in Photoshop? I can't believe I didn't know this until just this week! Using the Measurement tool (under the eye-dropper) draw a line along where the horizon SHOULD be, then click Straighten.

I'm a big fan of less reading. This should about do it!

That's all! Photoshop automatically rotates and crops your image so you don't have blank space along the edges. I seriously had no idea this tool even existed until now, and it's my new favorite thing!

I tested it out on this image of comet C/2011 L4 (PANSTARRS) from March 13, 2013. The comet was only about 10º from the crescent moon. In this photo, a plane happened to fly right over the moon during my 5 second exposure, making it a little more interesting. It's a neat picture, but the horizon wasn't quite straight. This new trick solves it instantly!

Plane over a crescent moon with comet Pan-STARRS below