So much going On this September
Sadly, summer comes to an end this month. But the great news for stargazing over Butler this September is that there’s so much happening in the heavens and along with that, there’s still plenty of great summer constellations to see. Sunsets are also earlier!
The full moon this month is next Sunday on Sept. 7. Most years, the September full moon is considered the annual harvest moon, but this one is a bit too early to be labeled as such. By definition, the harvest moon is the closest full moon to the autumnal equinox. So, the next full moon on Oct. 6 will officially be the Harvest Moon for 2025.
Saturn is returning to the early evening sky just in time for autumn. On Sept. 21, Saturn reaches what’s known as opposition, when Saturn and earth are at their minimum distance from each other this year, just over 795 million miles. Believe it or not, that’s considered close for Saturn. During opposition, Saturn and the sun are at opposite ends of the sky, making Saturn available all night long, rising in the east at sunset and setting in the west at sunrise. Oppositions between Saturn and earth happen every 378 days as Saturn and earth travel in their respective orbits around the sun.
To the naked eye, Saturn will appear as a moderately bright star barely above the eastern horizon toward the end of evening twilight. It’s easy to spot since it’ll be the brightest star-like object in that part of the sky. As tempting as it is to train your telescope on Saturn early in the evening, you’re better off waiting until at least 10 or 11 p.m. to let it get higher in the sky, above the blurring effects of our atmosphere close to the horizon. Over the last year or so, viewing Saturn through a telescope has been a bit of a bummer because its beautiful but very thin ring system, composed mainly of ice, has been nearly on edge from our vantage point on earth. This happens about every 14 years. The good news is that the angle of the ring system will very gradually begin to open up by early December and will continue that trend until 2032. In the meantime, though, the good news is that with the ring system pretty much out of the way, you can easily see many of Saturn’s moons, especially Titan, its largest satellite.
The very best time for serious evening stargazing this September will be the last two-and-a-half weeks of the month. That’s when the moon and all its light will be out of the evening sky. This is prime Milky Way galaxy time! Now, every single star we see in the sky is part of our home galaxy and relatively speaking, fairly nearby. But if you live in the dark countryside or can travel away from light pollution, you’ll see much more! Look for a milky ribbon of light reaching across the entire sky from the southwest to the northeast horizon, nearly bisecting the entire celestial dome. That’s the Milky Way band, the combined light of billions and billions of stars that make up the plane of our own Milky Way Galaxy. The brightest part of the band is on the southwest side near the horizon, where there’s a constellation that really looks like a teapot tipping toward the right. That’s the constellation Sagittarius, which, according to Greek mythology, is a centaur, a half-man, half-horse shooting an arrow. That bright puff of steam above the spout of the teapot is in the direction of the center of the Milky Way galaxy, about 26,000 light-years away. That area of downtown Milky Way would be a whole lot brighter except there’s a lot of opaque gas and dust in the way.
Elsewhere in the evening sky is a mixture of both summer and autumn constellations you can explore with the help of the attached map. Among them in the northern sky are Ursa Major and Minor, the Big and Little Bears, respectively. There’s also a sideways “W” in the northeast that outlines the throne of Cassiopeia the Queen. The great autumn constellation, Pegasus the winged horse, is rising in the eastern sky after sunset. Look for the big diamond of stars that outlines the torso of Pegasus. This is called the “Square of Pegasus.”
Attached to the left side of the big diamond is the constellation Andromeda the Princess, and within that is the Andromeda Galaxy. That’s the next-door neighbor of our Milky Way Galaxy, more than two million light-years away! You should be able to spot it with binoculars or a small telescope, appearing as a faint patch of light. If it’s really dark where you are you may even spot it with the naked eye!
Enjoy the longer nights of September!
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is also the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and at adventurepublications.net. Contact him at mikewlynch@comcast.net.
