The Ultimate Guide to Observing the Fall Sky (Northern Hemisphere)

Summer, it’s always sad to see you go. You came in like a blazing meteor bringing tremendous joy with long, warm sunny days and starry nights complete with the Milky Way and shooting stars filling the sky. But now, with September upon us, longer and cooler nights are here. The crisp autumn air fills the countryside with the aroma of hot apple cider and freshly harvested crops—no doubt gathered by farmers under the light of the Harvest Moon. Tree leaves transform into a blaze of brilliant colors—red, violet, gold, yellow, orange, and brown as if dressed in their best for a cotillion. It's time to embrace an exciting new season of change with Halloween and Thanksgiving on the horizon.   

Stargazers may have noticed summer constellations moving west while new constellations are rising in the east during evening hours. If you missed the summer Milky Way and some of the summer celestial objects, there's still time to see them from home or, better yet, from a dark sky site before they disappear entirely until the next viewing season. While autumn stars may not be as bright or spectacular as those found in winter, spring, or summer, the constellations are easy to recognize.

If you're new to astronomy and are just getting started using a telescope or binoculars, this guide is for you. It will help you familiarize yourself with the autumn constellations and popular celestial targets near or within them. So, put on your jacket, grab a warm beverage, a red flashlight, and let's head outside to check out the top sights of autumn! 

Popular Autumn Constellations and Asterisms

In ancient times, our ancestors looked towards the heavens and noticed that with every season, new groupings of stars appeared in the sky. The predictable cycle of visible constellations repeated year after year as Earth continued its orbit around the Sun. Using their vivid imaginations, stargazers envisioned these groupings as patterns that resembled mythological creatures, animals, and other objects for which they were named. You can't miss Cassiopeia's famous "M" or "W" depending on its orientation in the sky, as well as the Great Square of Pegasus. They are easy for beginners to find if you know where to look.

The most popular constellations of fall are best seen from mid-September until the end of the year. These include constellations of the zodiac: Aquarius, Aries, and Pisces, and constellations in the Perseus family: Andromeda, Cassiopeia, Cepheus, Cetus, Pegasus, Perseus, and Triangulum.

Aquarius

Aquarius

Known as the water bearer, Aquarius is a large constellation covering 980 square degrees. It is bordered by the constellations Pegasus, Pisces, Cetus, Sculptor, and Piscis Austrinus. Aquarius is one of the 13 constellations of the zodiac and resides in the area of the sky where the annual Delta Aquarids meteor shower takes place in the early morning hours of late July.

Andromeda

In Greek mythology, Andromeda, the princess daughter of Queen Cassiopeia and King Cepheus, was chained to a rock waiting to be Cetus, the sea monster's dinner. Andromeda is a prominent and recognizable fall constellation covering 722 square degrees of the sky. Andromeda appears as two long lines of stars in which the bright star Alpheratz seems to share one of Pegasus's square stars but is actually a part of Andromeda. Andromeda is also home to the brightest and most famous spiral galaxy visible to the naked eye, with which it shares a name. Find this constellation near Cassiopeia, Perseus, Triangulum, Pisces, and Pegasus. 

 Aries

Aries

Known as "The Ram" in Latin, Aries is usually listed as the first constellation of the zodiac due to the Sun's location within it around the beginning of Spring 1800 BC. For many civilizations, this was the start of the new year. Its symbol represents a ram's horns and is marked by Hamal, a second magnitude yellow giant star. You’ll find Aries near Pisces to the west and Triangulum to the north.

Cassiopeia

Cassiopeia, the wife of King Cepheus of Ethiopia, is a circumpolar constellation most prominent during the fall. Cassiopeia can be found between the north celestial pole and Andromeda. The brightest stars form an easy to recognize "M" or "W," which makes this constellation very easy to locate. Like the constellation Perseus, Cassiopeia is situated in the Milky Way and contains several deep-sky objects, including open star clusters visible in small aperture telescopes. 

 

Cepheus

Cepheus is one of the Greek constellations and named King Cepheus of Ethiopia. He is the husband of Cassiopeia and the father of Andromeda. Cepheus can be found near the North Pole and, like Cassiopeia, is a circumpolar constellation that is visible all year long in the Northern Hemisphere. Cepheus’ prominent stars form a five-sided figure that resembles a house. Cepheus contains some of the largest known stars in the Milky Way that are highlighted in this guide.

Cetus

Cetus

In Greek mythology, Cetus, the sea monster, was sent to dine on Andromeda while she was chained to a rock as a sacrifice. Cetus is located below Pisces and is visible in late fall and winter. Cetus is a large constellation taking up 1,231 square degrees and is the 4th largest constellation in the night sky.

Perseus

Perseus

Named after the Greek mythology hero, Perseus used Medusa's severed head to turn the sea monster, Cetus, into stone. Perseus is located along the Milky Way, southwest of Cassiopeia's famous "W." During mid-August, when Earth passes through the remnants of comet Swift-Tuttle, many shooting stars appear to "rain" from its direction. This famous meteor shower is known as the Perseids. Perseus is home to several deep-sky objects and a famous eclipsing binary star Algol, whose name in Arabic translates to "head of the demon." 

Pegasus

Pegasus

The winged horse is a northern constellation bordered by Cygnus, Pisces, and Andromeda. Pegasus can be found by drawing a line from Polaris (the pole star) through the west end of Cassiopeia. Pegasus is easily identified by its unmistakable giant "square" in the sky comprised of four stars, a centerpiece in the mid-fall sky. One of its stars, Alpheratz, is shared by the constellation Andromeda. Pegasus has many deep-sky objects, but most are too faint to be seen in small telescopes. 

Pisces

Pisces

Pisces, also known as The Fishes, is a large fall constellation of faint stars located in an area of the sky called the Sea. It can be found swimming next to Aries and just below the Great Square of Pegasus. Pisces' head forms a faint circle of stars connected to its body, resembling an eighth musical note. Pisces is best seen from a dark sky.   

Triangulum

Triangulum

Triangulum is one of the minor constellations in the night sky. It is located just above Aries and below Andromeda. Its name means "triangle" in Latin, and its three brightest stars resemble an arrow. Although there are no major star clusters or nebulae, Triangulum is home to the Pinwheel galaxy, a face-on irregular spiral galaxy belonging to the Local Group of galaxies. 

 

 

Top Autumn Celestial Objects

Cooler fall evenings are a splendid time to identify some of the new constellations and celestial objects becoming visible in the Northern Hemisphere after dusk. These objects are visible in most small to mid-aperture telescopes, from a modest 60 mm to 8" in aperture. If you have access to a pair of binoculars, use them, too! If you can travel away from city light pollution, your views will improve dramatically in darker skies. Autumn skies have abundant star clusters, the brightest and nearest galaxy, binary stars, double stars, and red supergiant stars. Unfortunately, we cannot cover them all in this guide, but this will provide a good starting point for exploring the most popular ones.

Algol

 

Algol

Also called the Demon Star, Algol is located in the constellation Perseus and has an apparent magnitude that varies between 2.1 and 3.4. It is one of the best-known eclipsing binary systems composed of two stars that orbit and pass in front of each other, causing the star to dim and grow in brightness. This occurs because the orbital plane of these two stars is almost edge-on, as seen from Earth. It was the first of its kind to be recorded back in 1667. Algol is derived from Arabic, meaning "head of the ghoul," or the Gorgon, Medusa whose head is covered in snakes. Scary indeed!

Almach

Almach

Almach is one of the best-known double stars in the sky and is located at one of Andromeda's feet. Through a telescope, the larger star appears golden, while the smaller star appears indigo blue. However, astronomers have discovered that Almach actually consists of four stars. The blue star is part of a triple star system, making Almach a quadruple star system! 

Andromeda Galaxy

Andromeda Galaxy

A favorite autumn target, the Great Andromeda Galaxy, is the brightest (apparent magnitude 3.4) and nearest spiral galaxy to our own Milky Way and is located in the constellation Andromeda. Also known as Messier 31 or NGC 224, the Andromeda galaxy is just 2.5 million light-years away from Earth and is the most distant object humans can see with their naked eyes. The Andromeda Galaxy is easily visible from a dark sky site and appears as a fuzzy patch of light. It is so large that a rich field telescope or binoculars are ideal for observing the entire galaxy in the eyepiece field of view. The galaxy's core and two satellite galaxies, Messier 32 and Messier 110, are visible in a telescope. Details in its spiral arms, though, are best seen in long exposure astroimages. The Andromeda Galaxy is on a collision course with our Milky Way galaxy, but according to NASA scientists, such an event won't happen for at least four billion years!

Double Cluster

Double Cluster

The Double Cluster is another favorite celestial target during autumn months as it rides high in the sky and appears exactly like its name—two-star clusters side by side. Also known as H and Chi Persei (NGC 869 and NGC 884), it is an open cluster located 7600 light-years away in the constellation Perseus and has apparent magnitudes of 3.7/3.8. To find the Double Cluster, use binoculars and look roughly halfway between the constellations Cassiopeia and Perseus. From a dark sky, it will appear as a visible smudge in the sky. A telescope will reveal an impressive view of two sparkling clusters filled with stars, including several supergiant suns. 

ET Cluster

E.T. or Owl Cluster

NGC 457 is a small open star cluster in Cassiopeia. It's also known as the Owl Cluster or the E.T. Cluster because its two brightest stars resemble an owl's eyes or the eyes of the extraterrestrial creature from the movie of the same name. With an apparent magnitude of 6.4, the cluster is just past naked-eye visibility, but it is visible in binoculars and through a telescope. If you use your imagination, the cluster's stars will resemble an owl's shape with its wings spread out as if it is ready to take flight into the cosmic realm. The cluster is always a favorite object to show kids at star parties.

Fomalhaut

Fomalhaut

Shining at magnitude 1.1, Fomalhaut is the brightest star in the Piscis Austrinus constellation, also known as "the southern fish." What makes this star unique is that its location in an area of the sky without any other bright stars. It stands out as a solitary star. In 1983, the IRAS satellite discovered infrared radiation coming from Fomalhaut—a dusty debris ring. Later in 2008, astronomers announced the discovery of an exoplanet named Fomalhaut b, or Dagon. Although you won't see the debris ring or exoplanet, you will see a brilliant star in your telescope when you visit the "loneliest" star in the sky. 

Messier 15

Messier 15

Also known as the NGC 7078, Messier 15 is a beautiful globular cluster located in the Pegasus constellation. It was discovered by Jean-Dominique Maraldi in 1746 and listed as the 15th object in Charles Messier's catalog. M15 is one of the oldest globular clusters and has an apparent magnitude of 6.2. It appears as a fuzzy star in binoculars, but in telescopes with at least 6" in aperture, M15 will reveal its bright core of densely packed stars estimated to be about 33,600 light-years from Earth. It measures roughly 210 light-years across. It is also the first globular cluster to have a planetary nebula, Pease 1, identified to be within it.

Messier 33

Messier 33

The Triangulum Galaxy, or NGC 598, is a nearby face-on spiral and third-largest galaxy in the Local Group. It is located three million light-years away in the small constellation Triangulum and is barely visible (apparent magnitude of 5.7) to the naked eye from an extremely dark sky in exceptional seeing conditions. Binoculars or low-powered telescopes are recommended due to the galaxy's low surface brightness distributed in an area of nearly four full Moons! Challenge yourself to find it! 

Messier 34

 

Messier 34

M34 or NGC 1039 is an open cluster of approximately 400 stars residing in the Perseus constellation about 5 degrees away from the Demon Star, Algol. It is about 1,500 light-years from Earth and has an apparent magnitude of 5.5. M34 can be seen in dark skies. Binoculars or a low-powered telescope are recommended. 

Mu Cephei

Mu Cephei

Mu Cephei is the famous Herschel's Garnet Star, a red supergiant and one of the most stunning luminous stars in the night sky. Located in the constellation Cepheus, "the King," it is one of the largest stars visible to the naked eye and has an apparent magnitude of 4.08. Mu Cephei's reddish color easily makes the star stand out in dark skies. With an absolute magnitude of -7.0, its luminosity is about the same as 350,000 Suns! Mu Cephei is now in its twilight years and will eventually go supernova. But don't panic; it may take millions of years to do so. You'll have plenty of time to view this beautiful carbon star in your lifetime. 

VV Cephei

VV Cephei

VV Cephei is a 5th magnitude red supergiant, variable binary star system located approximately 4,900 light-years from Earth and most fittingly in the constellation Cepheus, "the King." With an apparent magnitude of 4.9 to 5.4, it is one of the largest known stars in the Milky Way. This red supergiant is believed to have a mass of 19 solar masses. VV Cephei consists of two stars–a cooler red supergiant star and a hotter blue-white sequence star. Look for it just inside Cepheus' "square house" using binoculars or a telescope.

 

Other Notable Celestial Events this Autumn

Mercury - Sept 14

September 14 – Mercury at Greatest Eastern Elongation.

Mercury reaches its greatest eastern elongation of 26.8 degrees from the Sun. This will be the best time to view the innermost planet since it will be at its highest point above the western horizon after sunset.

Moon - September 20

September 20 – Harvest Moon.

The full Moon closest to the autumn equinox is called the Harvest Moon. In the Northern Hemisphere, the autumn equinox falls on September 22, while the full Moon falls on September 20, the Harvest Moon. It begins at 23:54 Universal Time. Look for it rising and basking the landscape with its warm orange moonlight. 

Venus - October 29

October 29 – Venus at Greatest Eastern Elongation.

Venus reaches its greatest eastern elongation of 47 degrees from the Sun. This will be the best time to view dazzling Venus since it will be at its highest point above the western horizon in the evening sky.

Moon - November 19

November 18, 19 – Partial Lunar Eclipse.

The Moon will pass through 97% of Earth's darker shadow or umbra and will darken significantly but not completely. This very deep partial lunar eclipse will almost be like a total lunar eclipse but not quite. The eclipse will be visible throughout most eastern Russia, East Asia, the Pacific Ocean, North America, Central America, and western South America.

Geminids Meteor Shower - December 13th to 14th

December 13, 14 – Geminids Meteor Shower.

The Geminids is the king of the meteor showers, producing up to 120 multicolored meteors per hour at its peak. It is produced by debris left behind by an asteroid known as 3200 Phaethon, discovered in 1983. The shower runs annually from December 7-17 and peaks this year on the night of the 13th and morning of the 14th. This year, the waxing gibbous Moon will block out most of the fainter meteors, but the Geminids are numerous and bright enough that they could still put on a good show. The best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Gemini but can appear anywhere in the sky.

 

Helpful Observing Hints

Tip #1: Use an Astronomy App or Star Chart

Use an Astronomy App or Star Chart
Using a detailed star map is a great way to learn the positions of celestial objects at any time of the year. It may be an old-fashioned learning tool, but it just works. Today's most modern and informative tools can be found in astronomy apps such as Celestron's SkyPortal mobile app. This full-featured planetarium app is included with purchasing any Celestron telescope, available from the Apple App Store or Google Play. SkyPortal instantly provides new telescope owners with a wealth of information at their fingertips, including audio and written descriptions about various objects. It also provides celestial coordinates, a real-time sky map, rise and set times, physical and orbital parameters.

Tip #2: Seeing Conditions

Seeing Conditions

Steady seeing conditions are critical while observing objects such as planets, the Moon, or double stars. However, deep sky objects such as nebulae and galaxies are less affected by poor seeing conditions. Avoid nights of bad seeing when our atmosphere is turbulent, and your targets appear like shimmering blobs in your telescope's eyepiece. Start with low magnification and work your way up if the views remain steady. You will be amazed at how sharp and detailed objects can appear during a night of good seeing.

Tip #3: Telescope Cooldown

Telescope Cooldown

Cool your telescope down! Make sure you bring your telescope outside about an hour or so before you plan to observe to cool it to ambient temperature. The telescope needs to reach thermal equilibrium with the outside air temperature to avoid distorted views. Telescopes with large mirrors and lenses may take longer to cool down for the best views.

Tip #4: Collimation

Collimation

Collimate, collimate, collimate! If you own a Newtonian or Schmidt-Cassegrain telescope, make sure your telescope's optics are collimated. It can make a difference when it comes to discerning fine detail. If the optics are slightly out of alignment, you may be cheating yourself out of seeing the clearest and sharpest details. Make it a habit to check collimation and adjust as needed once your telescope is cooled down. Most refractor telescopes generally do not need to be collimated.

Tip #5: Dress in layers

Dress in layers

Warm balmy nights may feel like shorts and t-shirt weather for the most part, but it's best to keep a light jacket handy just in case the temperature drops at night. Warm early fall nights can bring mosquitoes and other four-, six-, and eight-legged creepy crawlers out of the woodwork, so it's probably a good idea to cover up and apply bug spray, or else your evening of stargazing may turn out to be an unpleasant one.   

Celestron offers various outdoor electronics, including multipurpose devices that can keep your hands warm and your smartphone charged up while observing. You can browse our Elements line to learn more.

 

 

If you own a Schmidt-Cassegrain or EdgeHD telescope, make sure you use a dew shield to help protect your telescope's front corrector plate from the effects of dew. You can browse our Dew Prevention products.

 

You can learn about the night skies of the Northern Hemisphere with Celestron Sky Maps! This classic collection of seasonal star charts with a glow-in-the-dark luminous star finder has been around for years. It continues to be popular with beginning stargazers and seasoned amateur astronomers because it provides everything you need to find constellations quickly. 

 

 

Final Thoughts

Autumn is a transitional season and a perfect opportunity to stargaze with family and friends before the weather becomes chilly. Hopefully, once we get past the global pandemic, life can resume as we know it, and having safe, large public star party events will commence once again. With many of us so eager to get outside, stargazing has become a very popular new hobby for many and a great way to enrich one's curiosity about our amazing Universe. Now go out and use a Sky Map or the SkyPortal app to help you learn and identify the Autumn constellations and their fascinating backgrounds. You'll be amazed once you take your first glimpse of the Andromeda Galaxy, the Double Cluster, and especially the E.T. or Owl Cluster through your binocular or telescope from a dark sky site.

Clear skies and happy observing!

Other articles you might be interested in: Ultimate Guide to Observing the Universe