Astronomy Day is scheduled for September 27, 2025, offering an opportunity for the public to engage with the night sky. Organized by the Astronomical League, the event encourages stargazing with the naked eye, binoculars, or telescopes. This guide highlights six distinct celestial objects visible in the late September sky, from our own Moon to distant star-forming regions.
Whether you are a seasoned astronomer or a curious beginner, these targets provide a diverse tour of the cosmos. The objects range in scale and type, showcasing planets, stars, nebulae, and our own galaxy, the Milky Way.
Key Takeaways
- Astronomy Day 2025 takes place on September 27, an event designed to promote public interest in astronomy.
- Six celestial objects are recommended for observation: the Moon, Saturn, Polaris, the Orion Nebula, the Pleiades star cluster, and the Milky Way.
- These targets are visible with varying equipment, from the naked eye to amateur telescopes.
- Key details for locating each object, such as time of night and position in the sky, are provided for late September viewing.
Observing Our Closest Celestial Neighbor
The Moon in its Waxing Crescent Phase
The most familiar object in the night sky, Earth's Moon, offers a starting point for any stargazing session. On September 27, it will be a waxing crescent, illuminated at 34% capacity. Look for it approximately 15 degrees above the southwestern horizon shortly after sunset.
The Moon will be positioned near the bright red supergiant star Antares, within the constellation Scorpius. This phase occurs just two days before the first quarter, when the right half of the lunar disk will be fully lit.
Lunar Viewing Details
- Diameter: 3,475 kilometers (2,159 miles)
- Phase on Sept. 27: 34% lit waxing crescent
- Location: Southwestern sky at sunset
- Nearby Star: Antares
Even a standard pair of 10x50 binoculars can reveal significant surface features. Observers can identify Mare Tranquilitatis (the Sea of Tranquility), a large, dark plain near the lunar equator. For those with a telescope of at least 6 inches in aperture, a more detailed view is possible. In the nights following September 27, as the line between light and shadow (the terminator) moves across the surface, it becomes possible to locate the historic Apollo 11 landing site by using the craters Ritter, Sabine, and Moltke as reference points on the sea's southwestern edge.
Exploring the Outer Solar System
Saturn and Its Rings
September is an excellent month for observing Saturn. The gas giant will be visible high above the southeastern horizon in the hours after sunset, located in the constellation Pisces. To the naked eye, it will appear as a very bright, steady point of light, often referred to as an "evening star."
Viewing Saturn through an 8-inch telescope will reveal details such as the vast cloud bands that circle its surface. The planet's famous ring system, however, will present a unique view. Following a ring-plane crossing in March 2025, the rings are oriented nearly edge-on from our perspective on Earth. This makes them appear as a thin, bright line bisecting the planet, and the 4,800-kilometer-wide Cassini Division will be difficult to discern.
"The planet will appear as a bright 'evening star' to the naked eye around this time, just a week or so out from opposition, while an 8-inch telescope will allow you to resolve the vast cloud bands marking the gas giant's surface."
An interesting event occurs on October 6, when Saturn's largest moon, Titan, will cast its shadow onto the planet's cloud tops. This phenomenon, known as a satellite transit shadow, requires a telescope with at least an 8-inch aperture to be seen directly.
Navigating by the Stars
Polaris the North Star
Polaris, the North Star, is one of the most recognizable stars in the night sky. It is a supergiant star, about 46 times the size of our sun, located approximately 430 light-years from Earth in the constellation Ursa Minor, the Little Bear. Polaris also has a smaller companion star.
To find Polaris, first locate the Big Dipper asterism in the constellation Ursa Major. The two stars forming the outer edge of the Dipper's bowl, Dubhe and Merak, are known as the "pointer stars." An imaginary line extending from Merak through Dubhe points directly to Polaris.
A Shifting North Star
The entire northern sky appears to rotate around Polaris. However, this is not a permanent arrangement. Earth's rotational axis undergoes a slow wobble, a process called axial precession, over a 26,000-year cycle. This causes the position of the celestial north pole to shift, and different stars have served, and will serve, as the North Star over millennia.
Deep Sky Wonders
The Orion Nebula A Stellar Nursery
The Orion Nebula, cataloged as Messier 42 (M42), is a massive cloud of gas and dust where new stars are being born. Located 1,500 light-years away, it is one of the closest and most studied star-forming regions to Earth. Under dark skies, it is visible to the naked eye as a faint, fuzzy patch.
In late September, look for the nebula below the three prominent stars of Orion's Belt—Alnitak, Alnilam, and Mintaka. The constellation will rise high in the southern sky in the hours before dawn. The nebula's proximity has allowed telescopes like Hubble and the James Webb Space Telescope to study it in great detail, even imaging the protoplanetary disks forming around newborn stars, which provides insight into how solar systems form.
The Pleiades Star Cluster
Also known as the Seven Sisters, the Pleiades is an open star cluster containing more than 1,000 stars. It is located about 444 light-years from Earth and has a diameter of 43 light-years. To the naked eye, it appears as a small, milky patch of light in the eastern sky around midnight in late September, positioned above the red star Aldebaran in the constellation Taurus.
Using binoculars or a small telescope will resolve the cluster into dozens of brilliant, young, blue-white stars. The seven brightest members, which inspired its nickname, are named Asterope, Celaeno, Alcyone, Electra, Merope, Taygete, and Maia. It is believed that our own Sun was likely born in a similar open cluster billions of years ago before its sibling stars dispersed across the galaxy.
Our Home Galaxy The Milky Way
The final target is our own galaxy, the Milky Way. Since Earth is located within one of its spiral arms (the Orion Arm), we cannot see its full structure from the outside. However, we can observe the dense plane of the galaxy stretching across the sky.
To get the best view, find a location away from city lights. In the hours after sunset in September, the galactic plane will appear as a luminous ribbon of stars, dust, and gas arcing toward the southwestern horizon. This band runs through the Summer Triangle, an asterism formed by the bright stars Altair, Vega, and Deneb. Numerous other star clusters and nebulae can be found within and around this glowing expanse, offering a profound sense of our place in the cosmos.
