Physics Photo of the Week

November 16, 2012

Jupiter in Taurus
Look up in the high eastern sky any night this November and you see the Solar System's largest planet, Jupiter, dominating the scene.  This time-exposure with a tripod-mounted digital camera (eight 10-second exposures aligned and added together) makes many more stars visible than the un-aided eye can see. 

This part of the sky is in the constellation of Taurus, the bull.  The famous Pleiades star cluster (the "seven sisters") is plainly visible in the top of the image resembling a tiny "dipper".  Less well-known is the much larger Hyades cluster of stars dominating the lower central part of the image.  The Hyades cluster really is about the same physical size as the Pleiades, it is much closer to us (about 1/3 the distance as the Pleiades).

Where's the bull?  The long exposure that captures so many stars masks the familiar shapes of the asterisms.  The bright stars are subdued and the faint stars are given so much visibility.  The apparent field is too crowded.  The bull's nose is actually a "V" formation that is quite visible with the naked eye.  The "V" is essentially an outline of the brighter stars of the Hyades shown in the image at right. The brightest star in Taurus, Aldebaran, is also indicated.  The photograph largely suppresses the brightness of Aldebaran.  It is very dominant in the constellation, but not nearly as bright as Jupiter.  Click on the Jupiter-Aldebaran image and see a much larger image that clearly shows the importance of Aldebaran.

A close-up look at the Pleiades in the image at left reveals the noticeably blue color of the stars in the cluster.  That is due to the stars being very young and massive.  The more massive the star is the hotter it is.  These stars are all about twice the temperature of the Sun's 6000 K.  Alcyone, the brightest of the Pleiades has a mass of about 6 Suns, but its luminosity is about 2400 times the Sun's.  That means if Alcyone were in the Sun's position in the Solar System, the Earth would truly be scorched!  We will feature a better photo of the Pleiades when the College View Observatory is completed!

Due to Thanksgiving break there will be no Physics Photo of the Week next week.  Watch for the next photo on Friday, November 30, 2012.  Have a good Thanksgiving!

Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department. These photos feature 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

All photos and discussions are copyright by Donald Collins or by the person credited for the photo and/or discussion.  These photos and discussions may be used for private individual use or educational use.  Any commercial use without written permission of the photoprovider is forbidden.

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