|
 |
 advertisement
| |
|
|
|
|
|
Skywatch -- Polaris, the North Star
By Jeff Kanipe
posted: 05:10 am ET
09 August 2000
|
Brought to you by Starry Night Brought to you by Starry Night Wednesday, August 9 If you face north this evening, you will see the Little Dipper balanced on the tip of its handle, though its cup is beginning to recline toward the west. The star the Little Dipper its balanced on is Polaris the North Star. (You can use Dubhe and Merak in the Big Dipper as "pointer" stars to Polaris.) | What's up This Week | | The Moon is full on the 15th. Jupiter and Saturn rise just after midnight in the constellation Taurus. Venus hugs the western horizon after sunset, making it difficult to seein northern skies. The Summer Triangle is high overhead in the evening sky all this week andnext. | 
ASK THE ASTRONOMER Have a question for columnist Jeff Kanipe? Send it in and he'll try to answer it in our new online forum, debuting next week. | Besides its prestigious position of marking celestial north, Polaris has the distinction of being both a choice binary star for telescopes, as well as a Cepheid variable. As a binary, it's considered a nice "test" for small telescopes. In a 3-inch (7.6 centimeter), the 9th-magnitude companion lies 18 arcseconds southwest of Polaris. Since very little change has been detected in the positions of these stars with respect to one another it is thought that the orbital period is on the order of thousands of years. As a variable, Polaris isn't that exciting. Every four days, it fluctuates very slightly in magnitude -- from 1.92 to 2.07 and back again. Such a slight variation makes it difficult to detect with the eye alone, but it is a bit more obvious when monitored in a telescope. Polaris is about one-half degree from true celestial north, but is edging closer year by year. It will be nearest in 2102. Current Moon Phase
Updated every four hours, courtesy U.S. Naval Observatory ** Put the sky in the palm of your hand. Download SPACE.com's Skywatch, along with the latest space news, into your Palm Pilot or other handheld device. **Jeff Kanipe is the author of A Skywatcher's Year, an astronomy guide just published by Cambridge University Press. He is a former editor at Astronomy and StarDate magazines and a writer for the Earth & Sky radio series. The images in Skywatch are produced by Starry Night software.
|
|
|
|
|
