As September arrives, stargazers across North America are treated to a stunning array of celestial events. This month is particularly rich with astronomical phenomena, from Saturn's notable opposition to a spectacular lunar eclipse. Although the total lunar eclipse will not be visible from North America, it marks the beginning of a season full of celestial wonders. As the days shorten leading up to the autumnal equinox, September is an excellent time for evening stargazing. Below, we outline the key highlights for September 2025.
Throughout September, look for Fomalhaut, known as the “Autumn Star.” This bright star is located in the constellation Piscis Austrinus and is best visible from mid-northern latitudes during the fall. To spot Fomalhaut, ensure you have a clear view of the dark southern horizon, as it sits low in the sky.
Mark your calendars for September 7, 2025, as the full moon rises at dusk, earning the title of Corn Moon. This name is derived from the fact that the full moon in October is closer to the autumnal equinox on September 22. While this spectacular full moon will be visible, the accompanying total lunar eclipse will only be observable from Asia, Australia, and parts of the Pacific, leaving North America without any lunar eclipse viewings.
After dark throughout September, gaze towards the eastern horizon to witness the Great Square of Pegasus. This iconic asterism, comprised of four bright stars, is a classic feature of the fall night sky and is easily recognizable, even amidst urban light pollution. The appearance of the Great Square signals the changing seasons and the imminent approach of the September equinox.
On September 8, 2025, after dark, look for a nearly full gibbous moon positioned next to the golden planet Saturn in the constellation Pisces. This is an excellent opportunity to observe Saturn, as it approaches its annual opposition on September 20. A small telescope will allow you to view Saturn's exquisite ring pattern.
Before sunrise on September 16, 2025, the sky will reveal a stunning sight: a slender crescent moon, just 28% illuminated, positioned near Jupiter alongside the bright stars Castor and Pollux from the constellation Gemini. Together, they create a diamond-like formation, with each point approximately four degrees apart.
On September 19, 2025, just before sunrise, a 6%-lit crescent moon will align with Venus and Regulus, forming a tight grouping just above the east-northeast horizon. This is one of the month’s most impressive naked-eye conjunctions, making it a must-see event for astronomy enthusiasts.
Prepare for the best night of the year to observe Saturn on September 21, 2025. During its opposition, Saturn will rise at sunset and set at sunrise, shining brightly at magnitude 0.6. This is an excellent time to view the planet through a telescope, as its rings will be nearly edge-on yet still visible.
On September 22, 2025, a new moon will occur at 2:54 p.m. EDT, leading to some of the darkest skies of the month. In certain regions, including New Zealand, Fiji, Tonga, and Antarctica, observers will witness a partial solar eclipse. During this event, the moon will cover up to 79% of the sun at sunrise, creating a remarkable sight for those in the right location.
Also on September 22, 2025, at 2:20 p.m. EDT, the autumnal equinox will occur, marking the time when the sun is directly above the equator. This event results in roughly equal day and night lengths across the globe. From this point onward, nights will gradually grow longer, signaling the onset of fall.
For two weeks following the autumnal equinox, the chances of witnessing the Northern Lights increase. The solar wind interacts with Earth’s magnetic field, enhancing auroral displays around the equinoxes. While there’s no guarantee of sightings, this period is considered one of the best times for aurora viewing.
Throughout the month, after dark, stargazers can look towards the eastern sky to locate the Andromeda Galaxy (M31). Begin by finding the constellation Cassiopeia’s distinctive “W” shape and tracing a line from the rightmost “V” down to the bright star Mirach. The Andromeda Galaxy lies approximately two-thirds of the way from Mirach towards the horizon, making it the farthest object visible to the naked eye at 2.5 million light-years away. For enhanced visibility, consider using binoculars.
These celestial events are based on mid-northern latitudes, and for the most specific location-based information, it’s recommended to consult online planetariums such as Stellarium. Wishing you clear skies and a rewarding stargazing experience this September!
