September 2026 Calendar

At any moment of the day, countless awe-inspiring celestial events are unfolding in the sky. With a universe of options, it can be hard to pin down what to observe. The purpose of this calendar is to provide a peek into what’s happening in the sky and in the world of astronomy in general and provide a quick list of highlights that can jump start your own explorations.

September 2-3 – Close approach of Moon and M45

The waning gibbous Moon and the storied Pleiades star cluster with its brilliant blue stars will appear just over 1 degree apart in the early morning sky on to start off the month – meaning it’s a great time to see the duo in a pair of binoculars. Also know by the names Messier 45 or the more poetic Seven Sisters, the Pleiades open star cluster has a rich lore that crosses cultures and goes back thousands of years. It is relatively young, having formed within the last 100 million years, and lies relatively close to Earth at about 440 light years away. Found in the Taurus constellation, it  consists of more than 1,000 confirmed stars, although an average of only six are visible to the naked eye. A dark sky free of light pollution can help a dedicated observer see around a dozen Pleiades stars, but a good pair of binoculars or a low-power telescope can quickly reveal the more elusive members of this legendary cluster.

September 6 – Close approach of Moon and Mars

The Red Planet and the thin waning crescent Moon will make a visually close approach in the Gemini  constellation in the pre-dawn sky on September 6. Since there will be little lunar light interference, observers might also catch Gemini’s notable stars Castor and Pollux in the neighborhood. Pollux, which is the brightest of the two, is an orange giant with an orbiting planet, and Castor is an impressive six-star system.

September 8 – Close Approach of Moon and Jupiter

In the pre-dawn sky on September 8, look for the thin crescent Moon to cozy up to the giant planet Jupiter in the Cancer constellation. Observers in parts of North America, Greenland and the eastern-most portions of Russia will even be positioned beneath a lunar occultation of Jupiter – where the Moon will move in front of the planet. Unfortunately, for most this event will happen during daylight so any observing will require extreme caution and solar protocols. With the naked eye, Jupiter will manifest as a bright point of light, but a modest telescope may reveal the giant planet’s impressive cloud belts, its turbulent Great Red Spot or any of the four Galilean moons.

September 13/14 – Close Approach of Moon and Venus

The Virgo constellation will host a meet-up of the Moon and Venus in the evening hours of September 13/14. During the event, the thin waxing crescent Moon and the brilliant Venus will be 28.8 arcminutes apart, which means they could share the same field of view in some telescopes as well as binoculars.

September 16/17 – Conjunction of Moon and Antares

Mid-month, the waxing crescent Moon and the red supergiant Antares will be making a close pass in the Scorpius constellation. Even though they do not really share celestial real estate, it will seem like they do as they move closer together until they are visually separated by mere degrees. The binary star system Antares, which means “Rival of Mars” in Greek, is often mistaken for Mars due to its similar reddish hue. Generally identified as the 16th brightest star in the sky, Antares is an irregular variable with a red-orange glow that makes it truly pop. Closer observations with a moderate telescope could reveal its blue companion star, which can be highly challenging to discern.

Astrophotographer Andrew Corkill captured this image of the First Quarter Moon using an iPhone XR, an Explore Scientific ED152 Triplet Refractor and an Explore Scientific 82° Series 18mm Eyepiece. The iPhone was set at 1.9x magnification, and the result is a one-shot photo with no stacking.

September 19 – International Observe the Moon Night

It’s a steady presence in all our lives, but most people do not really take the time to appreciate Earth’s closest neighbor. Each year, International Observe the Moon Night aims to right that wrong by encouraging people around the globe to take a good long look at the Moon whether it is through a telescope, binoculars or even with the naked eye. The evening’s goal is to generate appreciation for this stunning celestial beauty and inspire people to delve deeper into the intriguing lunar landscape. For information on the vast range of activities scheduled throughout the world in relation to the event, click here.

September 22 – Venus Shines Super Bright

The ever-bright Venus will appear even more so as it reaches its greatest illuminated extent as an evening sky presence around September 22 in the Virgo constellation. After the Sun and Moon, Venus shines as the third brightest object in the sky so it is always a sight to behold. However, when it is at its greatest illuminated extent, Venus’ already impressive brilliance will be enhanced because the lit portion of the planet’s disk will cover more square area of the sky than at any other time during its current cycle as an evening star.

September 22/23 – September Equinox

A welcome sign of changing seasons for many, the September equinox is set to occur at 00:05 UTC on September 23 (7:05 p.m. CDT on September 22). For those in the Northern Hemisphere, this event is a harbinger of autumn, while in the Southern Hemisphere, it heralds the arrival of spring. The September equinox occurs when the Sun passes from north to south across the celestial equator, which lies directly above its imaginary counterpart - Earth’s equator. No matter where you are located, on this date, the Sun rises due east and sets due west, and day and night are almost equal in length.

September 25/26 – Neptune at Opposition

The fact that Neptune was first found by mathematical prediction rather than actual observation reveals how elusive Earth’s far-flung planetary sibling can be. But in September, amateur astronomers will be getting their telescopes ready for the planet’s move into a prime viewing position.

At 8:28 p.m. CDT  September 25 (01:28 UTC September 26), the blue-hued Neptune will reach opposition, which means it will sit directly opposite of the Sun when viewed from our planet. Around the same time, it also will be making its closest passage to Earth. These circumstances translate to an excellent observing opportunity.

Located in the Pisces constellation, Neptune will be highest in the sky at midnight local time and will have an apparent visual magnitude of 7.8. Although it is the fourth largest planet in our solar system, Neptune is not a naked eye object. To see it as more than a brilliant point of light, you will need to use at least a moderate-size telescope, which will hopefully render the planet as a steady blue disk.

September 27 – Close approach of Moon and Saturn

The ringed-beauty Saturn and the nearly-full Moon will make a visually close approach in the wee hours of September 27.  Look for the Moon in the Pisces constellation and Saturn in the Cetus constellation during the meet-up. The pair will be close, but not quite close enough to see in the same field of view of a telescope or binocular.

Astrophotographer James Hubbard captured this image of the Dumbbell Nebula with the aid of an Explore Scientific EXOS2 PMC-Eight Mount.

CONSTELLATION SPOTLIGHT: Vulpecula

Visible from 90° North to 55° South, Vulpecula – “The Little Fox” – is an unassuming constellation that lurks in the middle of the famous Summer Triangle asterism. At 268 square degrees, Vulpecula ranks as 55th in size out of the 88 constellations, but it still has some nice observing targets that are particularly well placed in September. One of its most popular sights in Vulpecula is the Dumbbell Nebula, which was the first planetary nebula ever discovered. Easy to find with binoculars and amazing in a telescope, the shape of this bright, double-lobed nebula has been compared to a dumbbell, an hourglass or an apple core. As an added bonus, the white dwarf that lies at the heart of the Dumbbell Nebula is one of the largest of its kind.

Another deep sky treat is Brocchi’s Cluster, which lies near Vulpecula’s border with the Sagittarius constellation. Although it is really more of a “chance alignment of stars” then a true cluster, it is worth visiting to view the binocular-friendly, 10-star Coathanger asterism that resides within it. Other deep sky offerings include the NGC 6823 open cluster, which is populated with blue-white stars; the NGC 6820 emission nebula, which can be viewed in the same field as NGC 6823; the ring-shaped NGC 6882 open cluster; the cross-shaped NGC 6830 open cluster; and the challenging NGC 6940 galactic star cluster. In terms of stars, Vulpecula’s brightest is Alpha Vulpeculae. Also known as Anser, the star is an optical binary with a red giant and an apparent magnitude of 4.44. Other stars of note are 23 Vulpeculae, which is the second brightest at an apparent magnitude of 4.52; the variable star 31 Vulpeculae; and HD 189733 – a binary with an orange dwarf and a red dwarf that is great for binoculars.

Want to navigate the night sky with ease?

The Tirion Double-Sided Planisphere is a comprehensive sky map for northern hemisphere stargazers located between the equator and latitude 60° north that makes it easy to identify what constellations and major celestial objects are up in your night sky based on the date and time.

This night sky guide, which features maps crafted by noted celestial cartographer Wil Tirion, uses a double-sided design to minimize the distortion that is inherent to any polar-centered projection. This design choice means observers can see truer representations of the constellations located outside the equator (noted by a green line) by simply flipping the planisphere over.

In addition to showcasing constellations, this planisphere indicates the location of notable variable stars, open clusters, nebulae and galaxies. Other features include a line representing the ecliptic, a faint blue band for the Milky Way and a magnitude scale that indicates the brightness of the stars that are shown.  

This astronomy planisphere is made of durable plastic that easily wipes clean, and the rotating components are secured with sturdy brass rivets for smooth manipulation. Guidance for using your sky map is printed on the device for quick reference.