Volume XVII, Issue 23 # June 4 - June 1, 2009

Sky Watch
by J. Alex Knoll

The Night Is Alive With Lights

It’s not just fireflies twinkling

With sunset around 8:30 this week, Saturn appears amid the lower flank of Leo the lion high in the southwest. While Saturn usually outshines its stellar neighbors, at first magnitude it glows no brighter than Regulus, 15 degrees to the northwest, and is less bright than Spica, 30 degrees to the southeast.

A look at Saturn through a telescope reveals why. The planet’s rings, formed of stellar ice, dust and debris, can account for more than 30 percent of the light reflected back to our eyes. Right now, the rings face us practically dead-on, significantly shrinking the disc you see in a telescope or the brightness of the spot you see in the sky. It will be some six years before we again see Saturn’s rings at their widest.

Sunset Thursday and Friday night find the waxing moon to either side of the dim constellation Libra, the celestial scales. Long ago, this faint constellation was seen as the claws of nearby Scorpius, but today it is the only inanimate object among the constellations of the zodiac — which literally means circle of animals.

The outline of the scale is made up of three third-magnitude stars: the brightest, Zubenelgenubi, marks the fulcrum; second-brightest is Zubeneschamali, marking the northern point; and Sigma Libra marks the southern tip. Give your eyes enough time to acclimate to darkness before taking a good look at Zubeneschimali, the only star that appears green to the unaided eye.

The near-full moon rises Saturday with sunset amid the constellation Scorpius. At 10pm, the red-giant Antares is less than one-third degree to the left of the moon, but over the following two hours the moon passes over the heart of the scorpion, occulting it from view.

Illustration: © Copyright 1925 M.C. Escher/Cordon Art-Baarn-Holland; Graphics: © Copyright 2009 Pacific Publishers. Reprinted by permission from the Tidelog graphic almanac. Bound copies of the annual Tidelog for Chesapeake Bay are $14.95 ppd. from Pacific Publishers, Box 480, Bolinas, CA 94924. Phone 415-868-2909. Weather affects tides. This information is believed to be reliable but no guarantee of accuracy is made by Bay Weekly or Pacific Publishers. The actual layout of Tidelog differs from that used in Bay Weekly. Tidelog graphics are repositioned to reflect Bay Weekly’s distribution cycle.Tides are based on National Oceanic and Atmospheric Administration and are positioned to coincide with high and low tides of Tidelog.