Sky of the Month: September 2026

September is the hinge month. The fall equinox lands on the 22nd, and from that point on the nights win. Andromeda climbs high enough to anchor an entire session on its own, Perseus is rising well before midnight, and the Summer Triangle targets from Lyra, Vulpecula and Sagitta are still up early in the evening before they slide toward the west. Call it the start of galaxy season.

The catch is timing. Almost every "best altitude" date this month clusters near the September 26 full moon, so the real dark-sky work happens earlier, around new moon on the 10th. Get that window right and September rewards you with some of the longest, coolest, most stable imaging nights of the year. All times in this article are Eastern Daylight Time (EDT, UTC-4). Adjust for your time zone accordingly.

1. At a Glance

• New moon falls on September 10 at 23:26 EDT. The window from roughly September 7 to 13 is your best broadband stretch of the month.
• Full moon is September 26 at 12:49 EDT. Most of the raw altitude peaks in this report land within a few days of it, don't trust those numbers blindly, see the deep sky section for the real story.
• No planetary oppositions or elongations, but Saturn is up nearly all night and the Moon passes an extremely tight 0.48° from Venus on September 14.
• The Aurigids peak September 1 but an 83% illuminated moon wipes them out. The Southern Taurids are ramping up toward a low-moon November 5 peak, worth marking now.
• 10P/Tempel, July's pick of the sky, has faded hard and sits only 11° above the horizon this month. Not a realistic target anymore.
• C/2024 J3 (ATLAS) is the comet to chase this month, riding high in Lyra at 84° altitude.
• 161P/Hartley-IRAS is brightening fast, worth watching as it climbs toward its best altitude at month's end.
• The fall equinox lands September 22. True darkness grows from about 7h12m on September 1 to nearly 9 hours by September 30, a much bigger jump than July's.

2. Moon Phases

The moon situation this month is the mirror image of a good one: new moon falls early, on September 10, but full moon on the 26th sits close enough to month's end that most objects' altitude peaks get caught in its glare. Plan your broadband sessions around the first half of the month.

3. Understanding Twilight

September is where the equation flips back in your favour. Sunset moves from 19:31 on the 1st to 18:36 by the 30th, and true darkness arrives earlier every single night. By the equinox on September 22, day and night are essentially even, and from there the dark side keeps winning. Here's what a mid-month night actually looks like, hour by hour.

Compare the darkest band here to July's diagram: it's noticeably thicker already, and it keeps growing through the month. By September 30 you're looking at nearly nine hours of true astronomical darkness, versus roughly seven at the start of the month.

~7:34 pm EDT

Civil Twilight ends

Sun 6° below horizon

Still looks like early evening, but the light is fading fast now compared to July. Venus and Saturn are already visible low in the sky. Use this window to finish setup, cool your camera, and get your polar alignment done before real darkness arrives.

~8:10 pm EDT

Nautical Twilight ends

Sun 12° below horizon

The sky darkens quickly at this time of year. There's still a glow near the horizon, but overhead targets in Cygnus and Lyra are already workable for framing. Faint galaxies like M31 still need to wait.

~8:46 pm EDT

Astronomical Twilight ends

Sun 18° below horizon

This is the threshold that matters, and in September it arrives noticeably earlier than it did in July. At 45°N mid-month, you're waiting until around 8:46pm EDT, more than two hours earlier than the July equivalent. That's a lot more usable night.

~8 hrs

True Darkness

Sun 18°+ below horizon

At mid-month, 45°N, true darkness runs from roughly 8:46pm to 4:52am EDT, about eight hours. Early in the month it's closer to seven hours, and by September 30 it stretches toward nine. This is one of the best stretches of the year for uninterrupted imaging time.

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The bottom line: September gives you both darkness and comfort: nights are long enough for a full imaging run, but temperatures haven't dropped into the punishing range yet. Start acquisition at astronomical twilight and you'll have far more usable hours than you did in July, without sacrificing sleep to get them.

4. Planets

No oppositions, no elongations this month. Deep sky is where the real action is, but Saturn is worth a look almost any night you're out, and there are two tight Moon conjunctions worth catching.

5. Meteor Showers

Only one shower is technically active this month, and the moon ruins it. The next one worth planning around, the Southern Taurids, doesn't peak until November, but with a nearly moonless sky, it's worth marking on the calendar now.

7. Comets

A quieter comet month than July. 10P/Tempel, last month's headline act, has faded out of contention entirely. C/2024 J3 (ATLAS) is the strongest target now, and 161P/Hartley-IRAS is brightening fast enough to keep an eye on heading into October.

8. Where to Go

The dark-sky window around September 7 to 13 is worth the drive, and cooler overnight temperatures mean better transparency than midsummer haze usually allows. Here's one solid option per province to get you away from city light.