Look up! Shining Saturn leads the Planet Parade in September
The string of planets continues to stretch across our predawn skies, with Saturn reaching its brightest in over 15 years.
Eyes to the sky for a lineup of planets in the predawn sky, September's Corn Moon, and Saturn at its closest and brightest since 2010.
Here is the Astronomical Guide for September 2025:
Sep 1 — Full Planet Parade still on display (predawn)
Sep 5/6 — Mercury drops out of the Parade
Sep 7-8 — Full Corn Moon
Sep 8 & 9 — Waning Gibbous Moon near Saturn
Sep 14 — Last Quarter Moon
Sep 16 — Waning Crescent Moon near Jupiter (eastern sky, predawn)
Sep 17 & 18 — Waning Crescent Moon between Jupiter and Venus (eastern sky, predawn)
Sep 19 — Waning Crescent Moon, Venus, Regulus close together (eastern sky, predawn)
Sep 20-21 — Saturn Opposition
Sep 21 — New Moon
Sep 22 — Fall Equinox
Sep 24 — Waxing Crescent Moon near Mars (western sky, after sunset)
Sep 29 — First Quarter Moon
The Moon
The astronomical events for September 2025, including the phases of the Moon, conjunctions, and oppositions. (Scott Sutherland, moon graphics from NASA's Scientific Visualization Studio, conjunctions courtesy Stellarium)
The Waxing Gibbous Moon greets us all on the first night of the month, and will light up the sky more and more throughout the first week, until the Full Corn Moon rises on the night of the 7th.
This will be the last 'normal' sized Full Moon for the year, as the October Hunter's Moon is the first in a string of 4 supermoons that will last into January of next year. Also, this Full Moon forms a nearly perfect 'syzygy' with the Earth and Sun, such that it will pass straight through Earth's shadow. The result will be a total lunar eclipse. However, the exact timing of the event has it peaking at roughly 2 p.m. EDT on the 7th. Thus, it will only be visible to those in Europe, Africa, Asia, and Australia, and will be long-over by the time the Moon rises in Canada.
The Waning Gibbous Moon will shine from the 8th through the 13th. Look for it near the planet Saturn on the 8th and 9th. Then, we'll see the Last Quarter Moon on the 14th, with the Waning Crescent Moon visible in the eastern sky before sunrise from the 15th through the 20th.
Look for the Moon near Jupiter on the 16th, between Jupiter and Venus on the 17th and 18th, and very close to Venus on the 19th. Observers throughout the eastern half of Canada can see the Moon and Venus in a very close lineup with the bright star, Regulus, that morning. The three form a triangle in the sky for anyone watching from western Canada.
The New Moon is on the 21st, making that likely the best night of the month for stargazing.
The Waxing Crescent Moon will be visible in the western sky just after sunset from the 22nd through the 28th. See it near Mars, very close to the horizon, just after the Sun sets on the 24th.
(Stellarium)
Lastly, we'll have the First Quarter Moon on the night of the 29th, and another Waxing Gibbous Moon on the last night of the month.
The Planet Parade continues
Throughout the month of September, one lone planet will be visible in our evening skies, as Mars hangs out above the western horizon after sunset. Night by night, as the Red Planet emerges from twilight, it will be closer and closer to the horizon.
It's our morning skies that will have the best display, though, due to the 'Six Planet Parade' continuing from August.
A simulation of the predawn sky on September 1, 2025, shows Mercury, Venus, and Jupiter among the morning constellations. (Stellarium/Scott Sutherland)
The first week of the month is best for seeing this. Mercury will have risen high enough in the predawn sky on at least the first few days to see fairly well, with Venus and Jupiter higher up in the eastern sky.
For the rest of the parade, you will need to scan from the eastern horizon all the way across to the southwestern sky, to where Saturn will be visible to the unaided eye. For those who have a telescope, the planet Uranus can be found to the southeast, near the Pleiades, while Neptune will be just up and to the left of Saturn.
This simulation of the predawn sky for September 1, 2025, shows the planets Mercury, Venus, Jupiter, Uranus, Neptune, and Saturn, strung across sky, to form a 'six planet parade'. Each planet is accompanied by an inset image showing a larger view of what it would look like through a telescope. (Stellarium/Scott Sutherland)
The parade loses a member fairly quickly as the month progresses.
From the 1st through to the 4th or 5th, Mercury should still be visible in the east. Exactly when we lose sight of it in morning twilight depends on the observer's location, when the Sun rises for them, and their elevation above sea level. By the end of the week, though, we will be left with only five members of the 'parade' in the sky.
The predawn planet parade on September 1 and 6, showing the changes in the parade's lineup. (Stellarium/Scott Sutherland)
Keep an eye on Saturn through the first three weeks of the month, as the planet grows brighter, night by night.
Saturn at its brightest
On the night of September 20, just before the summer season ends, the planet Saturn will reach its brightest in our night sky.
This point, known as 'opposition', is when Saturn lines up on the exact opposite side of Earth from the Sun.
Saturn Opposition. (Celestia/Scott Sutherland)
Saturn Oppositions come around roughly once every 377 days. This is longer than an Earth year because as we travel around the Sun to catch up to Saturn again, Saturn has also spent one Earth-year moving much slower along its own orbit. So, this adds about 2 extra weeks (give or take a day or so) to our journey so we can align once again.
In addition to the planet being in alignment with the Sun and Earth, Saturn Opposition also marks the time when the ringed planet is closest to us. On the night of the 20th to 21st, Saturn will be roughly 1.28 billion kilometres away.
While that's incredibly far away, it will still be the closest and brightest we've seen Saturn since March 2010, over 15 years ago.
Saturn in the southern sky during Opposition, on the night of September 20-21, 2025. The inset image, right, shows a telescopic view of the planet and its most prominent moons at 1:45 a.m. EDT. (Stellarium/Scott Sutherland)
Due to the shapes of Earth's and Saturn's orbits, oppositions between the two follow a 29-to-30-year cycle. It begins when the two planets reach opposition in the latter half of December, at which point the distance between them will be around 1.2 billion km. Roughly 15 years later, a late June opposition will occur with the two around 1.3 billion km apart. Then, another 15 years later (again, + or - 6 months), the next late December opposition will have them at their minimum distance again.
In 2025, we're still a few oppositions away from the next minimum of this cycle. With the last minimum distance in December 2003 and the last maximum in June 2018, the next minimum will occur in December 2032, when Saturn is just 1.201 billion km away.
September Constellations
The summer constellations are beginning to give way for the constellations of fall during the month of September.
(Stellarium/Scott Sutherland)
At the beginning of the month, the predawn skies will be dominated by Cancer, Gemini, Orion, Taurus, Eridanus, Cetus, Pisces, and Aquarius to the south. Lynx, Perseus, Cassiopeia, Andromeda, and Pegasus will be visible higher up in the sky. To the north, we will see Ursa Major, Ursa Minor, Draco, and Cygnus.
In the evenings, Pisces, Aquarius, Capricornus, Sagittarius, Scorpius, Libra, and Virgo will be arrayed along the southern horizon from east to west. Higher up, Pegasus and Cygnus will have swung around into the eastern sky, and will be joined by Aquilla, Hercules, Ophiuchus, and Bootes. Lynx, Perseus, and Cassiopeia will appear with Ursa Major, Ursa Minor, Draco, and Cygnus to the north.
(Stellarium/Scott Sutherland)
By the end of September, the constellations will have shifted, putting Aquarius off the western horizon by morning, making way for Leo in the east. In the evening, Virgo will be pushed out in the west to make way for Pisces in the east.