Physics Photo of the Week

January 27, 2006

Back on October 28, 2005, the Physics Photo of  the Week featured "Here Comes Mars".  In that photo, Mars was shown along with the Pleiades, Aldebaran, and the stars in Aries.  Another photo is shown at the left taken later in the season last fall.  The similar photo below was taken by Robin Gallagher during Astronomy class on November 18.  The "glow" in Robin's photo is the light pollution caused by both the campus lights and lights in nearby Swannanoa.

The word "planet" comes from the Greek word for "wanderer" because the planets "wander" among the stars.  See if you can see the position difference in these two images.  It is quite difficult because the images are taken at different scales and the camera is oriented differently to the sky for the two images.

A "quiz" was presented in the October 28 PPOW in which the reader is asked how Mars' position among the stars changes as the season progresses.     As a hint: all the planets orbit the sun towards the celestial east.  That is, the outer planets (those further from the sun than the earth) appear further east in the celestial sphere on successive orbital appearances.  The earth also orbits the sun towards the east.  The reader is asked to predict the apparent position of Mars among the stars if it is observed every two weeks or so throughout the season.

The answer to the quiz and an animation is shown on the following page.

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