September 2025 Stargazing Guide
Greetings Junior Scientists, Scientists and citizens of this great big weird, wild and wonderful world in which we live. As always I’m your humble science communicator, the great Orbax, coming to you from the Department of Physics at the University of Guelph and I’d like to welcome you to our September 2025 Star Gazing Guide.
Welcome back, junior scientists. As many of you have returned to your studies, so too have the long Autumn nights returned to us. By the 30th, sunrise will be as late as 7:18 a.m. compared to 6:45 a.m. on the 1st... and sunset moves up from 7:56 p.m. on the 1st to 7:03 p.m. on the 30th. That means we'll be ending our summer with over 12 hours of dark skies.
And these are truly the last few days of summer with autumn beginning on the 22nd and the equinox.
So with all that time to star gaze, what should we be looking for?
This month we take advantage of these long nights to spot some dim constellations,
prepare for the bright return of one of our ringed neighbors,
and we learn what the first day of autumn really means.
All this and more when we just take some time...
to look up
For September, let's see if we can spot the three smallest constellations in the sky. Do you remember the summer triangle? The large asterism made by connecting the dots between Vega, Deneb, and Altair? Look East after sunset and then look up until you can spot it. We're on the hunt for three small constellations. Vulpecula, the little fox, lies within the triangle itself. Just below the triangle is Delphinus, the dolphin, and just below that is Equuleus, the little horse. These constellations are tricky to spot, but the crisp September evenings should give you an advantage. And on top of that, Vulpecula houses the first planetary nebula ever discovered, the Dumbbell Nebula, M27, which can actually be seen with a home telescope or even large binoculars. Good luck, junior scientists.
Our planets this month are few but mighty. Venus will be visible bright and low in the East at dawn with Jupiter rising in the East in the early morning hours. The ringed giant Saturn will be visible all night long throughout September and will be at its brightest on September 21st when it undergoes opposition.
Our full moon this month is on September 7th.
100% illumination actually occurs during the afternoon that day, so the night of the 6th and the 7th will be super bright.
This last full moon of the summer is traditionally known as the Corn Moon or the Barley Moon and you can find it in the night sky lying between the stars of Aquarius and Pisces and appearing very close to Saturn.
Since this year's September full moon occurs early in the month, it is not considered the harvest moon.
The Anishinaabe peoples of the Great Lakes region refer to this Sept Moon as Waatebagaa-giizis - the “Leaves Turning Moon” while the Cree nation of central Canada honour the Moon with the bull moose's mating signal calling it Nimitahamowipisim, the “Rutting Moon”.
For the Mi’kmaw peoples, this year marks one of the rare occurrences where there are 13 Moons from the Spring time Moon until the next Spring time Moon. The September Full Moon is the 7th Full Moon in that year, with 6 before and 6 yet to come. This is known as A’qatiku’s —the Halfway Moon and occurs every 2 to 3 years.
Now, as I mentioned earlier, September 22nd is the first day of Autumn and here's why. We all remember the Earth is tilted at 23.5° with respect to the line perpendicular to the plane of our orbit around the Sun. One Earth year corresponds to one full solar orbit. In December, we talked about the winter solstice. And in June, we talked about the summer solstice. The solstice occurs on the day when we are either closest to or furthest away from the sun due to that tilt. These are the days when we experience the most daylight hours or the least daylight hours, the two extremes.
Now, exactly halfway between the solstices, we experience a day with equal amounts of daylight and nighttime hours.
This is known as the equinox.
The autumnal equinox occurs on September 22nd and denotes the first day of Autumn. After this point, our daylight hours will decrease until we reach the winter solstice. This phenomena occurs again in 6 months from now once we pass 180° through our orbit around the sun in the springtime for the vernal equinox.
As we head towards winter, the air gets colder, our days become crisper, and our nights just keep getting longer, giving us more time to cast our eyes skyward, gaze into the unknown, and peer through the thin veil of our atmosphere to see what lies beyond.
And all we need to do is just take some time...
to look up.
Woo! See you next month, junior scientists. And don't forget to have a science-tastic day.
Special thanks to Royal City Science's own planetary geo-chemist, Dr. Glynis Perrett for her help in preparing our star gazing guide.
And the Royal Astronomical Society of Canada.