We know planet Saturn, the zodiac of Libra, but what is Zubenelgenubi? This is a word to include into my knowledge bank and vocabulary!
Early on Saturday morning, Feb. 22nd., providing the skies are clear, we have an opportunity to catch sight of the last quarter moon pairing off with another planet, the ringed wonder of the solar system, Saturn.
Start looking low toward the east-southeast horizon shortly after 1:00AM local time on Friday night/Saturday morning. Soon after the moon emerges from beyond the horizon, we need to put our attention to a bright, non-twinkling yellow-white “star” shining sedately well above and to its right.
Eureka…that will be Saturn!
Baring any obstructions such as buildings or trees in that direction that might block the view, an observer might have to wait awhile as the celestial pair slowly climbs higher in the sky.
The duo will be at its highest, appearing roughly one-third of the way from the horizon to the point directly overhead (called the zenith), at around 5:30 a.m. local time. By that time, Saturn will appear about 7 degrees to the right of the moon. (A clenched fist held at arm’s length measures about 10 degrees).
If you look a similar distance to Saturn’s right, you may note the third-magnitude star with the fascinating name of Zubenelgenubi (pronounced “zoo-BEN-el-je-NEW-bee”) in the constellation of Libra, the Scales. If you have binoculars, train them on Zubenelgenubi; you’ll see that it’s a wide double.
With the use of a good pair of binoculars to peer at Zubenelgenubi – otherwise known as Alpha Librae – it reveals itself to be a double star. Astronomers have studied the motions of Zubenelgenubi’s two stars, thinking that it’s probably a binary – two physically related stars orbiting a common center of mass. However, the rather wide separation between these two stars must mean a long orbital period of perhaps 200,000 years. That suggests these two stars may not be bound by gravity!
Zubenelgenubi is a touch fainter than its fellow Libra star, Zubeneschamali. Nonetheless, Zubenelgenubi enjoys the alpha designation in the constellation Libra the Scales, probably because of its proximity to the ecliptic – the path of the sun, moon and planets in our sky. Zubenelgenubi is more intrinsically luminous than our sun. It resides some 77 light-years away.
Being I am was born in the sign of Libra (October), I believe we are very much influenced by the sun, moon, stars and constellations, I find this weekend’s alignment to be a fascinating experience which I intend to view, subject to weather conditions of course!
Cheers to a Cosmic Night, February 21st into the 22nd!