Physics Photo of the Week

Warren Wilson College

Feb. 25, 2005

Wandering Saturn

Saturn is very prominent in the skies this January, February, and March, but it doesn't stay put.  The images above were taken November 14, 2004 (left) and January 18, 2005 (right) by pointing the digital camera at the area of the sky and making about 10 15 sec time exposure images.  The images for each date were "stacked" or "co-added", then the two images for the two dates were "registered" so that the main stars line-up.  Notice that Saturn is noticably further to the right in the later image when compared with the Gemini bright stars: Castor and Pollux.  Planet is the Greek word for "wanderer".  As can be seen above, Saturn "wanders" among the stars.

The two images are "blinked" below.  Blinking is a technique astronomers often use to look for small changes in an object by comparing images of two different nights.  The stars are matched-up and the images are aligned, then displayed in quick succession.  Blinking, once very difficult and expensive, is now quite simple with the tools and software of digital photography.

Blinked images (Nov. 14, 2004; Jan. 18, 2005)

The whole sequence from Oct. 15, 2004 to Feb. 11, 2005 is shown in the animated image below.  (Large file: 158 kbytes).

Animated sequence (Oct. 2004 - Feb. 2005)

Saturn will be prominent in Gemini until April, 2005.

Webcam image wtih telescope. D. Collins, February, 2003

Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department.  These photos feature an interesting phenomena in the world around us.  Students, faculty, and others are invited to submit digital (or film) photographs for publication and explanation.  Atmospheric phenomena are especially welcome.  Please send any photos to

Click here to see all Physics Photo of the Week for 2005

Click here to see all Physics Photo of the Week for 2004.