Astrophoto: Polaris and Circumpolar Rotation in 30 Minutes

This recent image from astrophotographer John Chumack shows the Earth’s natural rotation in just 30 minutes of exposure time. Polaris, the North Star, is the stationary point over a Sequoia tree in Warrenton, Virginia, USA. “The rotational speed of the Earth at the equator is about 1,038 miles per hour,” John writes. “At mid-latitudes, the speed of the Earth’s rotation decreases to 700 – 900 miles per hour. You can notice star trails “rotation” in your photographs even in as little as 1 minute exposures. I notice star trailing in about 30 seconds with a 17mm wide angle lens. But the longer you leave the shutter open the more trailing and the more dramatic the effect!”

John used a Canon Rebel Xsi, ISO 400, .17mm Lens at F4.

See more of his work at his website, Galactic Images.

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