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Tag Archives: celestial mechanics

The Astronomy Picture of the Day (APOD) on March 17, 2014, shows warped star trails over Arches National Park, in Utah, USA.

Credit and copyright: Vincent Brady

The warping effect occurs because the picture is actually a full 360 degree panorama, horizontally compressed to fit your screen. As the Earth rotates, stars appear to circle both the North Celestial Pole, on the left, and the South Celestial Pole, just below the horizon on the right. While the eye-catching texture of ancient layered sandstone covers the image foreground, twenty-meter tall Delicate Arch is visible on the far right, and the distant arch of our Milky Way Galaxy and its dark dust lanes may be seen near the image center.

Credit: Vincent Brady


This movie, called “Death Valley Dreamlapse” illustrates the apparent movements of the celestial sphere (caused by Earth’s own rotation) during the course of the night, asĀ  (see Figure 4-19). See if you can identify what might be planes, satellites and meteors!

Credits: hosted by the LA Times. Shot and edited by Gavin Heffernan. Produced by Sunchaser Pictures.