One of Nature’s Great Wonders
Escape urban lights to see this sight
Each August, as the kids head back to school, the galaxy is tilted in such a way that the Milky Way stretches overhead in full glory. With Monday’s new moon, this may be the best week of summer to gaze on this river of stars. To fully appreciate it you’ll need dark skies away from any urban glow well after sunset. Give your eyes a few minutes to get accustomed to the darkness, tilt your head back and get lost in the glow.
From Perseus and Cassiopeia in the north-northeast, the Milky Way flows down through Cygnus the swan onto Aquila the eagle. From the eagle’s tail, the glow of stars splits, one section continuing to Sagittarius, the other to Scorpius in the southwest; the dark space in between is called the Great Rift. But this patch of the heavens is not bereft of stars. Our view of them is blocked by masses of interstellar gas and dust. Of course it isn’t just the flowing river of stars that make up the Milky Way but almost every star we see with the unaided eye, including our own sun. All are part of the same spiral galaxy. Our solar system is at the end of one of the spiral’s arms. When we look at the river of stars, we are looking toward the center of the galaxy, through layers of light that combined form the glowing band that we see on a beautiful dark night.
As evening twilight gives way to darkness, Mars and Saturn appear in the southwest. Mars has been inching toward the ringed planet night by night and will pass below it over the weekend, coming within three degrees. The two planets appear equally bright, but you should have no trouble telling Mars’ reddish hue from Saturn’s golden glow. While you’re comparing colors, look a few degrees to the north of the two planets for the star Zubeneschimali in the constellation Libra. This is the only star with a greenish glow visible to the unaided eye — at least to some. What about you?
Venus and Jupiter rise in the east-northeast before dawn. Jupiter is first to crest the horizon, but once Venus appears a few minutes later you’ll have no trouble telling the two apart, as the morning star is six times brighter than old Jove. The two planets are joined by the ever-so-thin waning crescent moon early Saturday morning.
The last of the naked-eye planets returns to view late this week. Look for Mercury Wednesday the 27th immediately in the wake of the setting sun and just a couple degrees from newly emerged waxing crescent moon.