In this episode of What's in the Sky this Month, Teagan reviews some of the beautiful celestial objects you can see in the month of September 2025!
Image credit: ESA/HUBBLE, CC BY 4.0/WIKIMEDIA
Saturn & Neptune at Opposition
Saturn is first, on the 21st, when it shines at magnitude 0.7. Ordinarily, the planet would be brighter, but this year its rings are almost edge-on, and since the rings are not reflecting nearly as much light, the planet is dimmer as a result.
Compare that to Neptune, the most distant planet, which is a paltry magnitude 7.8 at opposition on the 23rd. While Saturn is easily visible to the naked eye, you’ll need at least a pair of binoculars to detect Neptune. Similarly, Saturn always looks spectacular through a telescope, with rings and moons all easily seen, but Neptune will only show a tiny, blue disc.
OUR NEAREST NEIGHBORS
Mercury is too close to the Sun to be visible, but Mars clings to the west-southwestern horizon and appears near Spica in Virgo from the 4th to the 21st. Look for them at around 20 minutes after sunset; they’re closest on the 12th and 13th, while a crescent Moon hangs to the left of Mars on the 24th. Saturn and Neptune are in opposition (see above), and Uranus remains close to the Pleiades, with both best observed in the early hours of the morning. Jupiter is catching up to Castor and Pollux in Gemini, and is observable in the hours before dawn. Look for a waning crescent Moon between the planet and the two bright stars on the morning of the 16th. Venus appears within the same 10x50 binocular field of view as Regulus from the 14th to the 24th. However, there’s a stunning view on the 19th, when there’s a triple conjunction of the crescent Moon, Venus, and Regulus. Just one degree will separate the Moon from the star, with Venus midway between them both, making this an unmissable sight for binoculars and telescopes at low magnification. Lastly, there’s a full Corn Moon in Aquarius on the 7th and a new Moon on the 21st.
Image credit: NASA / ESA
Messier 15
Easily found close to Enif in Pegasus, M15 is bright enough to be seen with binoculars from suburban skies. A telescope at around 35x shows a comet-like hazy patch, while increasing the magnification to 100x shows a bright core that extends two-thirds to the cluster’s edge.
Image credit: Jim Mazur
Messier 27 - The Dumbbell Nebula
Along with M57, the Ring Nebula, the Dumbbell is one of the best planetary nebulae to observe in the celestial northern hemisphere. It can be spotted with binoculars, while a telescope at low power will show the two lobes that give the nebula its name.
Image credit: NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner (STScI), and T.A. Rector (NRAO)
NGC 7293 - The Helix Nebula
Another planetary, the Helix Nebula, is a more challenging telescopic target than either the Ring or the Dumbbell. This is thanks to its relatively large apparent size in the sky, which distributes its light over a wide area. A low magnification and an O-III filter will certainly help.
Image credit: NASA, ESA, STScI and P. Dobbie (University of Tasmania)
Messier 11 - The Wild Duck Cluster
M11 can be found close to the tail feathers of Aquila the Eagle, and is readily seen with binoculars as a small, compact patch with a starlike point. The cluster reveals its V-shape and a granular texture through a telescope at low power.
STELLAR CONCEPTS
Planetary Nebula: As red giant stars near the end of their lives, they dispel shells of gas and dust into space, which then expand and often grow to around a light-year in diameter. The term planetary nebula originated with the astronomer William Herschel, who likened their size and appearance to planets, as most appear small and circular when viewed through a telescope.
