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Physics Photo of the Week

October 28, 2005

Here Comes Mars!

Mars is approaching its closest approach to the earth for the current observing season.  (Conversely, earth is making its closest approach to Mars).  To view Mars this week, you need to look in the Eastern sky soon after 11:00 pm - the approximate time when Mars rises.  Alternatively, you can look high overhead at about 6:30 am - excellent for those who get up early.  The earth will be at the closest approach to Mars in late October at about 43 million miles.  The two planets were closer in late August, 2003 at 35 million miles.

The photo above was taken at about 5:30 am on Sept. 15, 2005 with a digital camera aimed at the Mars' region of the sky using a tripod.  To increase the visibility of stars, a series of 15 second exposures was taken.  16 of these time exposures were aligned and "stacked" using special software to compose a relatively clear image.  The contrast and colors were also enhanced to bring out the colors. 

Besides Mars near the center in this sky photo, the familiar Pleiades star cluster (often referred as "the Seven Sisters") is seen at top center, Aldebaran (alpha Tauri) and the Hyades "V-shaped" cluster in the upper left, and the 2 stars of Aries on the extreme right.  This same part of the sky was visited by Comet Macholz last winter (See PPOW for January 10, 2005) and reproduced at left.  Also notice in the top photo the bluish color of the Pleiades compared to the red color of Mars and Aldebaran, and the "medium" color of the stars in Aries on the right.

Mars will move in the sky throughout the fall and winter of 2005-06.  We (students, colleagues, and myself) will be taking photos of Mars in the sky to examine how Mars moves relative to the background of stars.  Here is a "quiz":  Both Mars and earth are moving around the sun, so the perspective position of Mars will change as the seasons progress.  Both planets (as well as the other 7 main planets of the Solar System) orbit the sun towards the east.  How is Mars going to appear in successive photographs?  Will it travel further east to join Taurus and Aldebaran, or will it move further west towards the constellation Aries?  The answer will not be published until December when more photographs have been made and stacked.

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.