The Moon joins Saturn, Mars, and the Scorpion’s Claws on the night of Sunday, 31 August. Looking toward the southwest after dusk on Sunday night, it will be easy to see the waxing crescent Moon form a compact, equilateral triangle with the two bright planets. But look a little further afield and find the two brightest stars in the constellation Libra, α and β Librae. These stars are known by their Arabic names “Zubenelgenubi" and "Zubeneschamali,” meaning the Southern Claw and the Northern Claw. These names refer to the ancient Greek concept of the constellation Scorpius; other ancient cultures saw them as a balance (Libra). The Bablyonians saw them as as scales sacred to the god Shamash, while the Romans thought Libra symbolized the scales held by Astraea, the goddess of justice.
Zubenelgenubi reveals itself to be a fine double star when viewed through an ordinary pair of binoculars. Zubeneschamali is less visually attractive, but may not have always been: Eratosthenes wrote that Beta Librae was brighter than Antares, the brightest star in Scorpius, in his time. Ptolemy, writing 350 years later, said it was as bright as Antares. It is unknown whether Antares became brighter or if Zubeneschamali dimmed in brightness. It appears to have been steady for the ~2,000 years since Ptolemy.
See Mars and Saturn separated by barely more than the width of the full Moon tonight in the southwestern sky after dusk. Slowly approaching each other in Earth’s night sky over the past several weeks, the Ringed and Red Planets reach minimum separation tonight in an astronomical phenomenon called an appulse. But the close approach is only an illusion: the two planets are separated in space by roughly 8 astronomical units, or about 745 million miles (1,200,000,000 km).
(Graphic credit: Astronomy Magazine)
The European Southern Observatory’s VLT Survey Telescope brings us a spectacular new view of the Triangulum Galaxy. Also known as Messier 33 and NGC 598, this galaxy is one of our nearest cosmic neighbors, located about three million light-years away in the small northern constellation of Triangulum. It is a spiral galaxy with a surprisingly low mass and almost absent central bulge. The new image beautifully highlights its massive star clusters, dust clouds, and brilliant, glowing red regions of hydrogen gas ionized by the powerful ultraviolet light of newborn stars. The VST, used to obtain the image, is a state-of-the-art 2.6-metre telescope at the ESO observatory perched atop Cerro Paranal in northern Chile.
Sedona, Arizona, named the world’s eighth IDA International Dark Sky Community. Yesterday, the International Dark Sky Association announced that it had designated the City of Sedona, Arizona, as part of its Dark Sky Places Program. Located in northern Arizona, Sedona is best known for its red rock scenery and has drawn scores of artists, naturalists, and outdoorsmen for decades. Now, through the dedicated efforts of city officials and local residents, new restrictions on outdoor lighting are helping to rein in the growth of light pollution there.
(Photo credit: Susan Amon)