Nights are Expanding!
Summer stargazing can be so comfortable! However, for many folks with Monday through Friday jobs, the wake-up call for work restricts extended nights under the stars to the weekends. In September, though, nightfall begins much earlier, especially later in the month. That's extra good news because Jupiter and Saturn return to the evening sky this September.
Autumn 2023 officially begins with the Autumnal Equinox. This year the equinox is on September 22nd or 23rd, depending on where you live on our planet. The northern and southern hemispheres will experience nearly equal amounts of daylight and darkness that day. From then until December 21st, the sun's daily path across the sky in the northern hemisphere will get progressively lower as days get shorter. Meanwhile, the sun's daily trek across the sky will get higher and higher in the southern hemisphere as daylight hours increase.
Serious evening stargazing in September will have to wait until after the week because of the crippling light of a waning full moon. Toward the end of the third week of the month evening moonlight will build back in. On September 29th, we'll have a full harvest moon since it's within ten days of the Autumnal Equinox.
The summer constellations still dominate the early evening sky. Among them is the moderately bright planet Saturn that'll put on a great show this month. Look for it in the low southeastern sky just after evening twilight. It'll be easy to spot since it's the brightest star-like object in that vicinity of the sky. On August 27th, Saturn and Earth reached what's referred to as opposition, their closest approach to each other in their respective orbits around the sun. Both planets are still relatively close to each other. On September 1st Saturn's just 815 million miles away, and at month's end, a little farther away at just over 831 million miles. Saturn's also available nearly all night long, not setting in the southwest until just before morning twilight kicks in.
This is definitely the time to check Saturn with a telescope, although I advise waiting to view it for at least a couple of hours after sunset so it has a chance to rise above the blurring effects of Earth's atmosphere near the horizon. Toward the end of the month, when Saturn is higher above the horizon at sunset, you can point your scope at it right away. Even with a small telescope Saturn's gorgeous ring system will blow you away. They're more than 150,000 miles in diameter but only about 50 feet thick on average. The only bummer is that the angle of Saturn's ring system from our view on Earth is tightening so we can't get as good of a look at it as we have in the past several years. Next year we'll hardly see the ring system as they'll appear edgewise. After that though our view of them will gradually improve year by year.
You should also see some of Saturn's moons, resembling tiny stars around Saturn. Titan is Saturn's largest moon, over 3200 miles in diameter, with a thick methane atmosphere. As with any telescope target, make sure you take long, continuous views of Saturn through your telescope so your eye can get used to the light level, allowing you to see more detail. You may also see Saturn more clearly as you catch thinner patches of Earth's atmosphere passing by. On September 26th, the nearly full moon will be perched just below Saturn. No telescope is needed to enjoy this tight celestial hug!
Right behind Saturn is Jupiter, rising above the eastern horizon around 10 p.m. early in September and around 9 pm late in the month. You can't miss the bright beacon of Jupiter. It's by far the brightest star-like object in the September night sky. Jupiter is nearing its closest approach to Earth in November, but it's close enough now to get a decent look at the behemoth planet with your telescope. You'll have to stay up late though, well past 11 pm early in September, to allow Jupiter to get above the blurring effects of our atmosphere near the horizon. By the end of September, you'll get a much better look at Jupiter's moons and cloud bands by around 10:30. The full moon will be in a tight conjunction with Jupiter on September 3rd and 4th. Don't miss that show!
The summer constellations still dominate much of the sky, with the "Summer Triangle" dazzling near the zenith as soon as evening twilight ends. Just look for the three brightest stars nearly overhead, and that's it. It's one of the best tools for helping you navigate that part of the sky because the three stars you see, Vega, Altair, and Deneb, are all the brightest stars in their respective constellations: Lyra the Harp, Aquila the Eagle, and Cygnus the Swan.
Another great summer constellation, Bootes the Herdsman, is perched in the early evening western sky. It looks just like a kite with the super bright star Arcturus marking its tail. Arcturus is the brightest actual star seen in the summer skies. Another summer classic is Sagittarius the Archer. According to Greek mythology, Sagittarius is allegedly a centaur, a half-man, half-horse shooting an arrow. What it really resembles is a teapot that's really easy to see!
Look for the Big Dipper proudly hanging by its handle in the northwest. The Big Dipper isn't an official constellation, but it outlines the rear end and tail of the great constellation Ursa Major, the Big Bear. The fainter Little Dipper, otherwise known as Ursa Minor, the Little Bear, is standing on its handle to the right of the Big Dipper with Polaris, the North Star, at the end of its handle. Everything in our celestial dome rotates around Polaris every 24 hours.
If you're lucky enough to stargaze in the countryside, you can't help but notice that ghostly ribbon of light that bisects the sky from the north-northeast horizon to the south-southwest. You're enjoying what's known as the Milky Way band, the thickest part of the disc-shaped plane of our home Milky Way Galaxy. The center of our home galaxy lies in the general direction of the teapot spout in Sagittarius.
For early morning stargazers, the bright planet Venus will greet you in the early morning eastern twilight skies. The planet named after the Roman goddess of love is just beginning its stint as our morning "star". You can see some of the bright constellations of winter, like Orion the Hunter, before the twilight gets too bright. As our world continues its circuit around our home star, Orion and the rest of his posse will take over our evening skies toward the end of the year, but let's not rush things.
Enjoy the September star splendor!
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul, and is author of the book, “Stars, a Month by Month Tour of the Constellations” published by Adventure Publications. Available at bookstores and online at www.adventurepublications.net.
If you have any astronomical questions or want me to write about something you’re seeing in the night sky drop me a line at email@example.com