In October, Saturn reaches opposition, and Jupiter hides behind the Moon; Other highlights to be seen this month are Mars crossing the Beehive, an asteroid that can be seen with binoculars, pieces of Halley’s Comet coming out of Orion, and the Moon passing in front of the Pleiades.
The crisp nights of October provide the backyard astronomer with a nearly ideal set of conditions. Darkness sets in relatively early, and a few hours can be enjoyed wandering the universe without a disruption to one’s sleep. Many of the sky’s best sights are still overhead, as the Milky Way crosses our zenith. The chilly nights may have diminished the cacophony of nocturnal insects that have kept companionship with us these past several months, but this also means that the mosquitoes have become inactive. Early morning observers can enjoy exploring the winter sky without enduring the typical winter nighttime temperatures. And finally, an added treat this year, magnificent Saturn returns to our evening sky in October.
Let’s start by taking a tour of the solar system, which has many exciting events to watch this month.
The Sun
We use the astronomical unit as defined by the distance between the Sun and Earth, but due to Earth’s elliptical orbit, we are only at this precise distance from the Sun twice per year. October 5 at about 2:00pm is one of those times, as we cross inside of 1.0 au on the way to perihelion on January 2. We will remain closer than 1.0 au to the Sun until April 4.
The last sunset in the 6:00pm hour is on the 17th. Sunsets will be earlier than 6:00pm until March 14.
The Sun passes the same right ascension as Spica on the 16th.
After a 42-day run through Virgo, the Sun enters Libra on the 31st, where it will spend the next 23 days.
The annual switch back to standard time (UTC – 0500) is at 2:00am EDT on November 1st.
The Moon
The Moon is at last quarter in Gemini on the 3rd. Rising at 10:26pm on the 2nd, this is the earliest rising last quarter Moon of the year. It is also among the most northerly last quarters of the year, transiting at 6:37am at an elevation of 75.1°.
On the morning of the 4th, the 42.0% waning crescent is near Pollux and Castor in Gemini.
Look for Ceres (magnitude 8.7) 3.1° west-southeast of the Moon at midnight on the 4th.
Just before 1:00am on the 5th, the 30.2% waning crescent Moon rises along with Mars, the pair being just 0.4° apart. The Moon approaches the Beehive Cluster, M44, throughout the rest of the morning. Occultations occur, but well into twilight when even the cluster’s brightest stars will be difficult to see telescopically.
A lunar occultation of Jupiter occurs early in the morning of the 6th, but unlike September’s event, this one is visible during the hours of darkness. Look for the 19.9% waning crescent Moon to begin to cover Jupiter at 4:25am. It takes over one minute for the Moon to completely cover Jupiter’s 33.7 arcsecond disk. It will be more dramatic when the giant planet begins to reappear from the Moon’s dark limb at 5:29am. The limb of the Moon should be clearly visible due to Earthshine, giving the event a very three-dimensional appearance.
The 11.6% waning crescent Moon is 3.5° southeast of Regulus, in Leo, on the 7th.
Just as spring is the best time in the Northern Hemisphere to observe the very young crescent Moon, autumn is the best time to observe the very old waning Moon. A great opportunity presents itself before sunrise on the 9th, when the 29-day (30 hours before new), 1.6% crescent rises at 5:42am.
Lunation 1284 begins with the new Moon at 11:50am on the 10th.
On the waxing side, the 5.5% crescent is 2.9° south of Mercury on the 12th.
On the 14th, the 17.5% waxing crescent Moon is 1.1° south-southeast of Antares.
The Moon is at first quarter at 12:12pm on the 18th, in Sagittarius. An hour past sunset, it is on the meridian, near the border with Capricornus, and 1.7° south-southwest of the globular cluster Messier 75.
October’s full Moon, traditionally called the Hunter’s Moon, is at 12 minutes past midnight on the 26th. It rises while the Sun is still above the horizon, at 5:14pm on the 25th. This makes it an ideal moonrise to photograph, as the surrounding landscape will be in daylight.
The Moon transits at an elevation of 64.5° at 12:24am, just 12 minutes after it reaches its fullest. This is a good time to observe the Moon with a telescope. Notice that even when it appears full, it still has a visible terminator. With an offset angle of about 4° between the Sun and our vantage point as seen from the lunar surface, we see the Moon as 99.87% Illuminated, so peaks and ridges along the southern limb may reveal some very narrow shadows under high magnification. The only time we’d be able to see the illuminated face of the Moon without any visible terminator is when it is totally eclipsed.
The full Moon sets at 7:49am, also presenting a photographic opportunity as this is after sunrise.
A lunar occultation of the Pleiades can be seen during the evening hours of the 27th, about an hour after moonrise, when the 94.6% waning gibbous passes directly in front of some of the cluster’s brightest member stars from 7:18pm to 8:45pm. The bright Moon will make the stars difficult to see with binoculars, so a telescope will be the best way to enjoy this event.
The Planets
Mercury is in the evening sky, low in the west-southwest after sunset. On the 1st, it is just over 8.0° to the right of, and slightly above Venus.
On the 6th, Venus is 5.1° south of Mercury.
Mercury is at greatest elongation, at 25.2° east of the Sun, on the 12th. However, this particular apparition is not so favorable to us here in the northern hemisphere, its latest setting time being just 45 minutes after sunset.
The innermost planet becomes 50% illuminated on the 18th, and shows a crescent phase on following nights, although it becomes very difficult to observe later in the month.
Although Venus retains an elongation angle of 30° from the Sun at the beginning of October, the low angle of the ecliptic and Venus’s position over 7.0° south of the ecliptic give the inner planet only about a half-hour of visibility after sunset. Observers with a clear southwestern horizon that make the effort to observe the bright planet will be rewarded with a view of its magnificent crescent, however, it will be very distorted due to the amount of atmosphere we’re looking through as it sits right over the horizon.
Venus sets at the same time as the Sun on the 13th, and will return to our morning sky in late October.
Our inner planet neighbor is at inferior conjunction on the 24th. This is the 9th inferior conjunction since the previous transit of Venus (June 2012), and we are 57 inferior conjunctions from the next transit of Venus (December 2117).
Venus will become visible in the morning sky, low in the east-southeast before sunrise, during the closing days of the month, which will provide a better opportunity to observe the slender crescent phase of Earth’s sister planet.
In early October, Mars rises at 1:00am in Cancer, and for about three weeks it will be within the same binocular field of view as Messier 44, the Beehive, passing directly in front of the cluster on the 11th. As it crosses the heart of the Beehive, try to notice the motion of the Red Planet as it moves 85 arcseconds per hour.
Moving east-southeastward at over ½° per day, Mars shows a distinct 89.9% illuminated gibbous disk, and is brightening past magnitude 1.0.
Mars crosses into Leo on the 30th, and on the 31st, Regulus, Jupiter and Mars are equidistant, with a 6° interval between each.
Jupiter is in Leo, moving towards Regulus at 10 arcminutes per day. With Venus setting early in twilight, Jupiter is now the brightest starlike object visible in the sky.
October’s celestial highlight is a lunar occultation of the giant planet on the 6th.
Not only will we see Jupiter covered by the Moon, but we will also be able to see each of its four Galilean moons occulted, providing us with a rare opportunity to observe a chain of five disappearances and five reappearances over a span of 70 minutes.
Watching occultations of Jupiter’s bright moons, particularly their reappearance from the Moon’s darkened limb, provides views of two unique phenomena.
Binocular observers may be familiar with how underwhelming it is to observe Jupiter through them. The planet is too small and too bright to reveal any features, and the Galilean moons, although easily bright enough to be visible, are too often lost in the glare of the planet, unless using the “giant” variety of 80mm or larger. An old observing challenge is to use a wire or the edge of a building to occlude Jupiter to help separate the moons from their parent planet, but trying to hold a steady view as the sky rotates above us makes this exceptionally difficult.
With the bright planet hidden behind the dark limb of the 19.9% crescent Moon, Europa’s reappearance at 5:24am on the 6th will be easily visible in just about any pair of binoculars. 135 seconds later and trailing Europa by just over one arcminute (1/30th of the apparent diameter of the Moon), Callisto’s reappearance may be a bit more challenging to detect, but the presence of the second satellite may be given away by its combined brightness with Europa. Io reappears 57 seconds later, and at a smaller 27 arcsecond interval behind Callisto, will pose an even greater challenge to binocular viewers, but again, the combined brightness may give it away. After Jupiter becomes visible, detecting the reappearance of Ganymede poses the same challenge everyday observers encounter while attempting to observe the Galilean moons with binoculars.
The second unique opportunity this occultation provides is the ability to perceive the motion of the Moon as it reveals not just Jupiter, but the Galilean moons.
If you have ever observed the Moon occult a star, you probably noticed that there is no transition time from the star being visible to hidden, and vice versa. The great distance to even the nearest stars results in them having practically no angular diameter (even the largest ones, like Betelgeuse, are measured in milliarcseconds), and result in them disappearing and reappearing practically instantaneously as the Moon passes in front of them at about one-half arcsecond per second.
With Jupiter’s moons appearing as tiny globes ranging from 0.74 to 1.24 arcseconds, although nearly unresolvable from starlike points in all but the largest of telescopes, they take about two seconds to transition from being fully hidden and fully visible, an easily perceptible event to observe in nearly any telescope.
Additionally, this occultation gives us a sense of the scale of the solar system. With our Moon, approximately the same size as Jupiter’s moon Io, and with the Jovian system being over 2,300 times farther away, Io appears just under 2,300 times the apparent diameter of our Moon.
Don’t miss this rare opportunity to watch our dynamic solar system in motion.
In addition to the planet itself, the four Galilean moons are putting on their own show this year, as the Jovian system is close to equinox, which results in the opportunity to watch the giant moons occulting and eclipsing each other. Several of these events are visible to us this October, as shown in the table.
On the 17th, watch Ganymede emerge from eclipse at 2:57 am, and go into occultation behind Jupiter about an hour later.
Saturn is at opposition in Cetus on the 4th. Appearing opposite to the Sun in our sky, the ringed planet rises around sunset, sets around sunrise, and is highest in the sky just after midnight. This is also the time that Saturn appears largest and brightest in our sky, with its globe extending 19.7 arcseconds, its ringspan 44.6 arcseconds, and its combined magnitude of 0.3. Opposition is also the time of minimum shadow offset.
Since we’re closest to Saturn, this is also the best time to observe its myriad of moons. Titan, 48% larger in diameter than Earth’s Moon, and the largest of Saturn’s 293 known moons, shines at magnitude 8.3, easily accessible to observers using small aperture telescopes. The 5,149-kilometer diameter moon appears as a 0.84 arcsecond disk, which may just be resolvable in a large aperture telescope using high magnification during a night of exceptionally steady seeing.
Even though it may be bright enough to be detectable with binoculars, Titan only appears up to 200 arcseconds from the planet during its 15.9 day orbit. As this is only about 1/10th of the apparent diameter of our Moon, this, like Jupiter’s moons, makes it quite difficult to detect against the glare of its parent planet. A small telescope with a modest amount of magnification, however, should easily reveal the giant moon
Saturn’s mid-sized moons, Rhea, Tethys, and Dione, have orbits inside of Titan, and appear at magnitudes ranging from 9.6 to 10.3, putting them within reach of a 4-inch telescope under ideal conditions.
Iapetus, another mid-sized moon that orbits Saturn at about three times the distance of Titan and completes an orbit every 79 days, has two distinctly different hemispheres and is tidally locked with Saturn, such that the hemisphere that is forward has accumulated a dark, sooty layer, while its trailing hemisphere, which faces Earth when the moon is to the west of the planet, can be two whole magnitudes brighter than its leading hemisphere. It should be visible with a 6-inch telescope in early October, when we are looking at its back side. Its next western elongation comes in mid-December.
Mimas and Enceladus, two inner satellites that have orbits of 0.94 and 1.37 days, respectively, can be observed with a 12-inch telescope under ideal conditions.
When looking at Saturn with your unaided eyes, notice that the planet is directly north of Diphda (α Ceti) by about 20.0° (their alignment is closest on the 8th), and the pair cross the meridian together, as does the Andromeda Galaxy. Keep watching this alignment as Saturn continues its retrograde (westward) motion through December 11.
The waxing gibbous Moon appears near Saturn on the 23rd and 24th.
Uranus, in Taurus, is easy to locate midway between the Hyades and Pleiades clusters.
An interesting historical anecdote is that the first known instance of Uranus’s precovery (that is, an observation made of the seventh planet before it was confirmed as a member of our solar system by William Herschel in 1781) was one made by John Flamsteed, first Astronomer Royal, in 1690. Flamsteed was tasked with creating a star catalog, one that is still used today, numerically identifying the brightest stars in each constellation by right ascension. While recording the stars in Taurus, Flamsteed marked the star 34 Tauri as a 6th magnitude star in the constellation located fairly close to the Pleiades, which contain designations from 16 to 28.
However, if studying a star atlas today, either a classical bound volume or digital edition, you will be hard-pressed to find a star with the designation 34 Tau. That is because, soon after it was marked by Flamsteed, it had moved, because it wasn’t one of the fixed stars, but the planet Uranus.
Incidentally, Uranus has completed exactly four orbits since Flamsteed first spotted it, and in 2026 it has returned to the same region of sky, in mid Taurus, just beside the Pleiades, and we can easily find “34 Tauri” by using a neighboring pair of Flamsteed-designated stars in the 30s: 39 and 37 Tauri.
Aim your binoculars just 4.0° southeast of the Pleiades, towards Aldebaran. You’ll find a pair of stars, aligned along the same direction and separated by ten arcminutes (about ⅓ the apparent diameter of the Moon), at magnitudes 4.4 and 6.0, with the brightest of the pair, 37, towards the Pleiades. Follow a line through the dimmer star 39 Tau about 2.1° to find Uranus, a pale blue-green object of magnitude 5.6.
Note that Uranus is moving retrograde (westward) during October, and by mid-month, will be slightly closer to 39 Tauri, and more south-southeast, less in line with the pair of 37-39.
Neptune is in Pisces, about 8° west of Saturn, and about midway between ι Ceti and ω Piscium.
Look about 10.0° west-southwest of Saturn to find a quadrilateral of 4th and 5th magnitude stars which measures approximately 0.9° x 2.5°, its long dimension stretching north-northwest to south-southeast. From the northernmost star, magnitude 5.1 29 Piscium, move 3.0° to the northeast to locate Neptune, which should appear as a pale, bluish speck of magnitude 7.7.
Minor Planets
Pluto, in southwestern Capricornus, 8.9° south of Dabis (β Capricorni), is near the meridian after dusk, placing the 14.5 magnitude dwarf planet in a good position for early evening observers.
Located in southeastern Capricornus 7.9° south of Dabih (β Capricorni), Pluto reaches eastern quadrature on the 26th. This is the last best time to observe it before it gets too low in the sky to be easily visible until June 2027.
Ceres, at magnitude 8.7, is in Gemini, and can be found 3.0° northwest of Wasat (δ Geminorum). Our closest dwarf planet continues to move eastward, and on the 10th-11th it lies 1.4° directly north of the magnitude 3.5 star. If Wasat sounds familiar, it may be that you’ve encountered it on the Astronomical League’s list of Double Stars. It has a magnitude 6.5 companion that lies 5.5° to the southwest, an easy pick in a small telescope.
October is the best month to observe Vesta, as the large asteroid is closest to Earth on the 9th, at a distance of 1.480 au, and reaches opposition four days later, on the 13th. At magnitude 6.4, it is just beyond the limit of naked-eye visibility for most observers, but it is within easy reach of binoculars, even on moonlit nights.
Vesta is located in a sparsely populated area of sky in north-central Cetus, but it can be easy to locate given its relative brightness against the dim stars, and by applying a little bit of geometry aided by Saturn.
Starting at Saturn, look south about 20° to Diphda (β Ceti). From the midpoint of a line connecting the two, move east about 10° to magnitude 3.6 θ Ceti. Vesta remains within the same binocular field of view as this star during much of October as the bright asteroid moves west-southwestward approximately ¼° per day.
At the beginning of the month Vesta is 7.0° northwest of θ Ceti, and 1.4° north-northeast of magnitude 5.0 HD 10550.
At magnitude 6.4, Vesta is 4.2° due north of θ Ceti on the 19th.
Pallas is also at opposition in October, on the 11th, at a distance of 1.850 au and magnitude 8.2. Also in Cetus, θ Ceti can be used as a guide to find it as well.
In early October, Pallas is 4.1° due south of Diphda, and it moves south-southwestward at about ⅓ ° per day.
Due to its highly inclined orbit with respect to the ecliptic, Pallas is diving southwestward, deep towards the belly of Cetus, the whale. Find the magnitude 10.0 asteroid 6.0° due east of Diphda (β Ceti) on the 23rd.
Eris, the distant world that led astronomers to rethink the classification of Pluto, is at opposition on the 19th, at the great distance of 94.474 au, 2.6 times more distant than Pluto. Located in Cetus, its magnitude 18.6 glint can only be seen in images.
Comets
Although not expected to peak brighter than 10th magnitude, Comet 161P/Hartley-IRAS is well-positioned for observation during the evenings in October.
The comet is in Aquarius, moving west-northwestward early in the month. On the 5th and 6th, it is within the water jar asterism.
On the 13th, you will have a good reason to visit the oft-neglected constellation Equuleus, as the comet is just 1/3° north of Kitalpha (α Equ). While traversing the tail of Delphinus, it passes 2.1° north of Caldwell 47 (NGC 6934), a magnitude 8.8 globular cluster.
Meteors
The Draconid meteors, a low-rate meteor shower consisting of remnants of Comet 21P/Giacobini-Zinner, peaks on October 9, close to the new Moon, from a point near the head of Draco.
Although comet 1P/Halley may be far away beyond the orbit of Neptune, parts of it return to our skies every October during the Orionid meteor shower. This shower is active nearly the entire month, centered around a peak on October 21-22, when, under ideal conditions, as many as 20 swift meteors can be seen per hour. The 2026 display competes with a bright waxing gibbous Moon, so the best time to observe is before dawn, when the radiant is nearly overhead, and the Moon will have set.
The Southern Taurids, a low-rate yet reliable shower that peaks in early November, can also be seen during October, and is notable for producing slow-moving fireballs.
Stars & Beyond
Look to the northwest during early evenings in October to find our familiar Big Dipper in its upright orientation, properly containing autumn’s harvest within its bowl. Arcturus, our zero-magnitude beacon of spring, is finally departing the evening sky, and soon after, Corona Borealis dips out of view, taking with it the Blaze Star, which we’re still waiting for its next outburst.
Just as Arcturus slips out of sight, another zero magnitude star comes into view: Capella (α Aurigae), low in the northeast. Capella, a close binary star that lies 43 light years away, is nearly circumpolar from our latitude, and will be a part of our evening sky well into June.
In the east, Pegasus and Andromeda are coming into view, replacing the summer constellations as the hours march later into the night, and the nights march later into the month.
For the early evening observers, however, we can still see some of summer’s best highlights, with Cygnus high overhead. This month, we’ll take a deep sky journey to an easily accessible, yet often overlooked, Messier star cluster, M39 (NGC 7032).
Follow the Milky Way about 9° north from Deneb (α Cygni), arcing slightly to the east, to land on a bright knot suspended within the mottled galactic glow.
At a distance of just under 1,000 light years, M39 is a relatively large and loose open cluster containing at least 30 stars. It is circumpolar from the latitude of Seagrave Observatory, but is best positioned for early evening observers during October, when it arcs high overhead, just 7° from the zenith. Its combined magnitude 5.5 glow is visible without optical aid for observers under exceptionally dark skies, but can be easily detected with binoculars under moderate light pollution or moonlit skies.
About a dozen of its brightest members are spread over an area of sky slightly smaller than that of the Moon.
The cluster was discovered by Guillaume Le Gentil in 1749, and Messier added it to his list of non-comets on October 24, 1764.
With an estimated age of around 280 million years, many of M39’s member stars are massive, hot stars on the main sequence.
While not as spectacular as the Pleiades in Taurus, M39’s relative brightness, large size, and accessible northerly declination make it a worthwhile destination for any size telescope during a significantly long portion of the year.
Be sure to stop and see M39 the next time you’re touring the Milky Way, and keep this object on your list of easy objects whenever the celestial swan is over your horizon.
