September is a sky-gazer's dream, packed with celestial events that are sure to catch your eye, whether you’re a seasoned astronomer or just someone who loves to look up. This month, the universe puts on a show that’s too good to miss, from Mercury shining bright in the morning to the stunning rise of the Super Harvest Moon.
But that’s not all—Saturn and Neptune have some surprises in store, with rare lunar occultations and Neptune’s own opposition. And as the month wraps up, the Fall Equinox will signal the official change of seasons, adding an extra touch of magic to the night sky.
Whether you’re up early or staying up late, September has something in the stars just for you.
7 Stellar Celestial Wonders in September 2024
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September 4:
Mercury’s Morning Peak – Greatest Western Elongation - September 8:
Saturn Shines Bright – Saturn at Opposition - September 17:
Saturn’s Disappearing Act – Lunar Occultation of Saturn - September 17:
The Super Harvest Moon Rises – Full Harvest Moon - September 18:
Neptune’s Hidden Moment – Lunar Occultation of Neptune - September 20:
Neptune’s Night Out – Neptune at Opposition - September 22:
Balance in the Sky – Fall Equinox
September 4th
Mercury Shines in the Morning: Catch It at Its Best During Greatest Western Elongation
On September 4th, Mercury will reach its greatest western elongation, which means it’s one of the best times to spot this elusive little planet. While the technical moment happens at 10:24 pm ET, the real magic happens a few days later. On September 7th, Mercury will reach its highest point in the morning sky, shining brightly at magnitude -0.3. This is your golden opportunity to see Mercury at its best as it moves away from the Sun’s glare.
Why Is This Event Special?
September 4th kicks off Mercury's peak visibility in its August-September 2024 morning appearance. As it moves out of inferior conjunction (when it was hidden between Earth and the Sun), Mercury quickly brightens and shows off a more noticeable gibbous phase. This makes it easier to spot as it rises higher and shines brighter in the morning sky.
During this period, Mercury will be about 18° away from the Sun, making it much easier to catch a glimpse of this speedy planet before the sunrise washes it out.
However, the absolute best time to see Mercury is on September 7th, when it will be at its highest point above the horizon, making it an ideal moment for early risers to enjoy this celestial treat.
When and Where to Look
If you're in the Northern Hemisphere, set your alarm early on September 7th—around 5:00 am local time, just an hour before sunrise. Look towards the eastern horizon, where Mercury will be shining its brightest. If you're in the Southern Hemisphere, Mercury will also be visible in the pre-dawn sky, though conditions might be a bit trickier. Still, keep an eye on the eastern horizon, where it will be rising through the constellation Leo.
Mercury’s Position and Best Viewing Time
On the morning of September 4th, Mercury will be:
- Right Ascension: 09h 47m 40s
- Declination: +13° 20'
- Constellation: Leo
- Magnitude: -0.3
- Angular Size: 7.2"
By September 7th, when it reaches its highest altitude, Mercury will still be in Leo, close to the bright star Regulus, which can help you locate it in the twilight.
What You’ll Need for the Best View
While you can definitely spot Mercury with the naked eye, a pair of binoculars or a small telescope will make the experience even more exciting. With a telescope, you might even catch Mercury’s gibbous phase—a rare treat that makes this planet stand out.
- Binoculars: A 10x50 pair will give you a wide view of the twilight sky, making it easier to find Mercury.
- Telescope: A small telescope with at least 50x magnification will bring Mercury into sharper focus, showing it as more than just a bright dot.
Viewing Tips
To get the best view of Mercury, you’ll need clear skies and an unobstructed eastern horizon. Try to find a spot away from city lights where the sky is dark and clear. Also, check the weather ahead of time—a crisp, cool morning with low humidity will give you the best chance to see Mercury in all its glory.
September 8th
Saturn at Opposition: A Must-See Night for the Ringed Planet
Mark your calendars for September 8th, when Saturn takes center stage in the night sky. At 12:27 am ET, Saturn will reach opposition, a perfect time to catch this stunning planet at its best. Opposition means that Saturn will be directly opposite the Sun in the sky, making it visible all night long. Even better, Saturn will be at its closest to Earth, so it will appear brighter and larger than at any other time this year.
Why Saturn’s Opposition Is So Special
When Saturn is at opposition, Earth sits directly between Saturn and the Sun. This alignment means Saturn will rise as the Sun sets and stay visible until sunrise, giving you an all-night show. Saturn will be shining in the constellation Aquarius, reaching its highest point around midnight. This is the ideal time to see the planet at its most impressive, with its disk measuring 19.2 arcseconds across and glowing at magnitude 0.6.
A particularly cool phenomenon to watch for is the Seeliger Effect. Around the exact moment of opposition, Saturn’s rings will brighten noticeably compared to the planet itself. This happens because the ice particles in the rings, usually casting shadows on each other, are fully illuminated by the Sun from the same angle we see them. The result? A breathtaking display where the rings seem to glow even more brilliantly.
When and Where to Watch
The best time to catch Saturn at its peak is around midnight local time when it’s highest in the sky. This will give you the clearest view, with minimal atmospheric distortion. Saturn will be visible all night, but the sweet spot for viewing is between 11:00 pm and 1:00 am, depending on where you are.
To find Saturn, look towards the southeastern sky in the evening. By midnight, it will have moved toward the southern sky. If you’re in the Northern Hemisphere, find a spot with a clear view of the southern horizon. In the Southern Hemisphere, Saturn will be a bit higher in the sky, making it even easier to see.
Saturn’s Position at Opposition
At the time of opposition, Saturn will be positioned at:
- Right Ascension: 23h 10m 40s
- Declination: 7° 39' S
- Constellation: Aquarius
- Magnitude: 0.6
- Angular Size: 19.2"
These details place Saturn firmly in Aquarius, so once you know where to look, it should be easy to find. And with its bright glow, Saturn will stand out beautifully.
What You’ll Need to Get the Best View
While Saturn is visible to the naked eye as a bright point of light, a telescope is where the magic really happens. Here’s how to get the best view:
- Telescope: A telescope with at least 75x magnification will let you see Saturn's rings in detail. If you have a larger telescope, try cranking up the magnification to get an even closer look at the rings and maybe some of Saturn’s moons.
- Filters: Using a yellow or orange filter can enhance the contrast in Saturn’s rings, making them pop against the planet.
- Astrophotography: If you love taking pictures of the night sky, this is a perfect chance to capture Saturn at its best. Use a DSLR or an astronomy camera with a long exposure to capture the rings and surface details.
What to Expect While Viewing
To get the best view of Saturn, you’ll want clear, dark skies. Try to find a spot away from city lights, preferably in a rural area with an open view of the southern sky. Atmospheric conditions like humidity can affect your view, so check the weather forecast and pick the clearest night around September 8th.
Since Saturn will be up all night, you’ll have plenty of time to take it in. However, the best viewing conditions will be around midnight when Saturn is highest in the sky, giving you the sharpest view.
September 17th
Lunar Occultation of Saturn: A Celestial Hide-and-Seek
On September 17th, the Moon will pull off a stunning celestial trick—hiding Saturn from view in a rare lunar occultation. If you’re in the right place, like the western U.S., Australia, western Canada, or northwestern Mexico, you’ll get to see Saturn disappear behind the Moon, only to reappear a short while later. It’s like a cosmic magic show, and if you’re lucky enough to be in the viewing zone, you won’t want to miss it!
What Is a Lunar Occultation?
Think of a lunar occultation as the Moon playing hide-and-seek with a distant celestial object—in this case, Saturn. As the Moon moves in front of Saturn from our viewpoint on Earth, it temporarily blocks the planet from view. Depending on where you are, you might see Saturn completely vanish behind the Moon or just barely miss it. Either way, it’s a fascinating event that showcases the dynamic nature of our solar system.
For those in the occultation path, Saturn will disappear behind the Moon for a little while, only to pop back into view as the Moon continues its journey across the sky. Even if you’re not in the exact path, you can still enjoy the spectacle of the Moon and Saturn appearing very close together—a beautiful sight in its own right.
When and Where to Watch
If you’re in one of the lucky regions where the occultation is visible, here’s when to look up:
- Western United States: Set your alarm early! The occultation happens in the pre-dawn hours of September 17th, roughly between 4:00 am and 5:00 am local time. Make sure to start watching at least 15 minutes before so you don’t miss Saturn’s grand exit behind the Moon.
- Australia: For those in Australia, the show starts in the evening on September 17th. If you’re in Sydney, Melbourne, or nearby areas, look to the sky between 8:00 pm and 9:00 pm local time. It’s a perfect way to wrap up your day with some stargazing.
- Western Canada: Similar to the western U.S., the occultation will take place in the early morning hours. In British Columbia and Alberta, expect the event to unfold between 3:00 am and 5:00 am local time, depending on your exact location.
- Northwestern Mexico: In areas like Baja California, the occultation will also occur in the early morning, around 4:00 am to 5:00 am local time.
If you’re not in these regions, don’t worry—you can still enjoy the close conjunction of the Moon and Saturn. They’ll appear side by side in the night sky, creating a stunning visual that’s worth staying up (or waking up) for.
Saturn’s Position During the Occultation
When Saturn is momentarily hidden by the Moon, it will be located in the constellation Aquarius, shining at a magnitude of 0.6. Here’s where it will be:
- Right Ascension: 23h 08m 00s
- Declination: 7° 56' S
- Magnitude: 0.6
- Angular Size: 19.2"
This means Saturn will be fairly easy to spot once it reappears from behind the Moon. Just look towards Aquarius in the night sky, and you’ll see it shining brightly.
How to Get the Best View
Want to make the most of this event? Here’s how:
- Binoculars: Even if you’re just using binoculars, you’ll get a better view of the action. A pair of 10x50 binoculars will help you see Saturn’s “disappearance” and “reappearance” more clearly.
- Telescope: A small telescope is ideal for getting up close and personal with Saturn and the Moon. With at least 50x magnification, you’ll see Saturn’s rings as they slip behind the Moon, a sight that’s truly special.
- Timing: Make sure you’re set up and ready a few minutes before the event begins. Things can happen quickly, so it’s good to be prepared!
What to Expect While Viewing
For the best experience, find a spot with clear, dark skies—away from city lights if possible. Since the occultation occurs late at night or early in the morning, the air should be cooler and clearer, which is ideal for stargazing. Double-check the weather forecast so clouds don’t spoil the show, and try to find a location with an open view of the southern sky, where the Moon and Saturn will be.
September 17th
The Full Harvest Supermoon: A Night to Soak in the Glow
Get ready to enjoy a spectacular sight on September 17th—the Full Harvest Moon! But this isn’t just any full moon; it’s a supermoon, making it even more special. At 10:34 pm ET, the Moon will reach its full phase, lighting up the sky with its extra-large, extra-bright presence.
What Makes This Full Moon Special?
This year’s Full Harvest Moon is extra special because it lines up with the Moon’s closest approach to Earth, known as perigee. This means the Moon will look slightly larger and brighter than usual—a supermoon! While the difference might be subtle to the eye, there’s something magical about seeing a super-sized Moon rise just after sunset, making the night feel a little more extraordinary.
On September 17th, the Harvest Moon will rise shortly after sunset, reaching its peak brightness at 10:34 pm ET. Because the Moon’s orbit is slightly elliptical, it’ll be around 357,000 km away from us at perigee. This close distance will make the Moon appear as one of the largest full moons of the year, with an angular size of about 33.5 arcminutes.
Why Is It Called the Harvest Moon?
The Harvest Moon is the full moon closest to the autumnal equinox, which happens on September 22 or 23. What makes it unique is that, unlike other full moons, the Harvest Moon rises at nearly the same time for several nights in a row. This gave farmers extra light to gather their crops before the fall frosts set in, which is how it got its name. This tradition has been celebrated for generations across different cultures, from Native Americans to Europeans, and the name “Harvest Moon” has stuck around ever since.
When and Where to Watch
To catch the best view of the Harvest Moon, plan to start watching as it rises in the east just after sunset on September 17th. The exact time of moonrise depends on where you are, but it usually happens within 15 minutes of sunset. As the Moon climbs above the horizon, it will appear larger and more golden, thanks to an optical trick called the Moon illusion.
- Northern Hemisphere: The Harvest Moon will rise in the east and be visible all night long. If you’re in the U.S. or Canada, it’ll rise shortly after sunset, offering a stunning view as it lights up the sky.
- Southern Hemisphere: While the Harvest Moon is tied to Northern Hemisphere traditions, those in the Southern Hemisphere will still enjoy a gorgeous full moon. It won’t have the same seasonal meaning, but it’ll still be a sight to see, rising in the east and glowing all night.
Where the Moon Will Be
At its fullest, the Moon will be positioned at:
- Right Ascension: 23h 44m 20s
- Declination: 2° 46' S
- Constellation: Pisces
- Angular Size: 33'24"
This puts the Moon in the constellation Pisces, close to the celestial equator. This means it’ll be high in the sky for most of the night, making it easy to spot from just about anywhere.
How to Get the Best View
You don’t need any special equipment to enjoy the Harvest Moon, but a few tools can make the experience even better:
- Binoculars: A pair of 10x50 binoculars will help you see the Moon’s surface details more clearly, including its craters and dark plains (maria).
- Telescope: If you have a telescope, even a small one, you can get an up-close look at the Moon’s textures and features. It’s a great way to see the supermoon in all its detailed glory.
- Photography: This supermoon is a perfect target for photography. Use a DSLR camera with a telephoto lens, or attach your smartphone to a telescope to capture the Moon’s beauty. Play around with exposure settings to bring out the lunar surface’s richness.
What to Expect While Viewing
For the best view, clear skies are a must. The Moon will be bright enough that light pollution won’t be much of a problem, but you’ll want to find a spot with an open view of the eastern horizon so you don’t miss the dramatic moonrise. Check the weather to make sure clouds don’t spoil the show, but remember, the Moon will be up all night, so you’ll have plenty of chances to see it even if clouds block your view at first.
September 18th
Lunar Occultation of Neptune: A Cosmic Peekaboo
Stay up late on the night of September 17th into the early hours of September 18th, and you might catch a celestial game of peekaboo as the Moon briefly hides Neptune from view. This rare lunar occultation will be visible from several parts of the world, including Canada, the U.S., Mexico, and southeastern Alaska. If you’re in one of these lucky spots, you’ll get to watch Neptune disappear behind the Moon’s bright side, only to pop back out from the dark side shortly after.
What Is a Lunar Occultation?
Imagine the Moon playing a cosmic game of hide-and-seek. As it moves in front of Neptune, it temporarily blocks the distant planet from view. Because the Moon is so close to us, the exact timing and visibility of this event will vary depending on where you are. Some people will see Neptune vanish completely behind the Moon, while others might see them just barely miss each other in the night sky.
This occultation will take place late in the evening or early in the morning, making it perfect for night owls and stargazers who love a bit of cosmic drama.
When and Where to Watch
If you’re in Canada, the U.S., Mexico, or southeastern Alaska, you’re in prime position to witness this event. Here’s when to look up:
- Eastern U.S. (EDT): In places like New York City, Neptune will start to disappear behind the Moon around 1:50 am on September 18th, reappearing about an hour later.
- Central U.S. (CDT): In Chicago, Neptune will be occulted around 12:50 am CDT.
- Mountain U.S. (MDT): In Denver, the show begins just before midnight on September 17th, with Neptune vanishing around 11:50 pm MDT and reappearing after midnight on the 18th.
- Pacific U.S. (PDT): On the West Coast, the event happens earlier in the evening, around 10:50 pm PDT on September 17th.
- Canada: Similar to the U.S., in Toronto (EDT), the occultation starts at 1:50 am, and in Vancouver (PDT), it kicks off at 10:50 pm on the 17th.
- Mexico: In Mexico City (Central Time), Neptune disappears around 12:50 am local time, just like in the Central U.S.
- Southeastern Alaska (AKDT): Here, the occultation begins earlier, around 9:50 pm on September 17th, finishing up just after 11:00 pm.
Even if you’re outside these regions, you can still enjoy a beautiful close conjunction of the Moon and Neptune, where they’ll appear very close together in the sky.
Neptune’s Position During the Occultation
When Neptune is hidden by the Moon, it will be sitting in the constellation Pisces:
- Right Ascension: 23h 55m 40s
- Declination: 1° 54' S
- Magnitude: 7.8
- Angular Size: 0.02"
At magnitude 7.8, Neptune is faint and not visible to the naked eye, so you’ll need binoculars or a telescope to see this event.
How to Get the Best View
Here’s what you’ll need to catch this cosmic event:
- Binoculars: A pair of 10x50 binoculars should be enough to spot Neptune as a tiny dot near the Moon. This will let you watch as Neptune disappears and reappears.
- Telescope: For a closer look, a small telescope with at least 100x magnification will make the occultation more dramatic, showing Neptune as more than just a dot.
- Timing: Be ready a few minutes before the event starts so you don’t miss anything. Keep your eyes on the Moon and Neptune to catch the exact moment of disappearance and reappearance.
What to Expect While Viewing
Clear skies are key to seeing the lunar occultation of Neptune. Since this event happens late at night or early in the morning, find a spot with a clear, unobstructed view of the southeastern sky. Light pollution can make it harder to see Neptune, so if possible, head to a darker location away from city lights. Check the weather to ensure you’ll have clear skies, and prepare to stay up a bit later for this rare and fascinating sight.
September 20th
Neptune at Opposition: A Chance to Spot a Distant Blue Gem
On the evening of September 20th, Neptune will reach opposition, making it one of the best times to try and spot this distant blue planet. At 8:08 pm ET, Neptune will be directly opposite the Sun in our sky, meaning it will be visible all night long. This is also when Neptune is closest to Earth for the year, so if you’ve ever wanted to see this elusive giant, now’s your chance!
What Happens During Neptune's Opposition?
When Neptune is at opposition, Earth is directly between Neptune and the Sun. This special alignment means that Neptune rises in the east as the Sun sets in the west and stays visible until the Sun comes up again. The best time to catch it is around midnight, when it’s high in the sky, giving you the clearest view.
Even though Neptune is at its closest to us during opposition, it’s still an incredible 28.89 AU (astronomical units) away—that’s about 2.7 billion miles! Because of this vast distance, Neptune appears as a tiny, star-like point of light, with a disk size of just 2.4 arcseconds. Its brightness at opposition will be magnitude 7.8, so you’ll need a telescope to see it.
Best Times and Places to Watch
Neptune will be hanging out in the constellation Pisces during opposition, making it easier to locate if you know where to look:
- Evening to Midnight: Neptune rises in the eastern sky at sunset and stays up until sunrise. The sweet spot for viewing is around midnight, when it’s at its highest and least affected by atmospheric distortion.
- Northern Hemisphere: If you’re in the Northern Hemisphere, look towards the southeastern sky in the evening. As the night goes on, Neptune will rise higher in the south.
- Southern Hemisphere: In the Southern Hemisphere, Neptune will be even higher in the sky, giving you a great vantage point. Look to the eastern sky after sunset.
Neptune’s Position at Opposition
At opposition, Neptune will be located at:
- Right Ascension: 23h 55m 20s
- Declination: 1° 56' S
- Constellation: Pisces
- Magnitude: 7.8
- Angular Size: 2.4"
These details place Neptune in Pisces, where it will stay throughout the night. While it’s not the brightest object in the sky, knowing exactly where to find it will help you track it down with your telescope.
How to Get the Best View
Because Neptune is so far away and faint, here’s what you’ll need to see it:
- Telescope: You’ll want at least 100x magnification to resolve Neptune as a small disk instead of just a point of light. If you have a larger telescope, you might even catch a glimpse of Neptune’s largest moon, Triton.
- Star Charts or Astronomy Apps: Use these tools to locate Pisces and pinpoint Neptune’s position in the sky. They’ll make it easier to find your target, especially if you’re using a manual telescope.
- Filters: A blue or green filter can help enhance Neptune’s color, making it easier to distinguish from nearby stars.
What to Expect While Viewing
For the best viewing experience, head to a location with dark skies, far from city lights. Clear weather is a must, as clouds can block your view of this distant planet. Because Neptune is so dim, even a little light pollution can make it hard to see, so aim for the darkest skies possible.
Neptune won’t change much in brightness or position over a few hours, so you’ll have plenty of time to observe it. However, the clearest and most stable view will be around midnight when it’s at its highest point in the sky.
September 22nd
The Fall Equinox: A Moment to Welcome Autumn (or Spring!)
As the air turns crisp and the days grow shorter, September 22nd marks a special time—the Fall Equinox at 8:42 am ET. This is when we officially say hello to autumn in the Northern Hemisphere and spring in the Southern Hemisphere. The equinox is a unique moment when day and night are nearly equal in length all over the world, making it the perfect time to pause and appreciate the balance between light and dark.
What Is the Fall Equinox?
The word "equinox" comes from the Latin words for "equal night," which perfectly describes this day when we get about 12 hours of daylight and 12 hours of darkness. This happens because the Sun’s path crosses the celestial equator—an imaginary line in the sky that extends from Earth’s equator—causing the Sun to rise exactly in the east and set exactly in the west, no matter where you are on the planet.
The equinox occurs because of Earth’s 23.5° tilt on its axis as it orbits the Sun. This tilt is what gives us our seasons. On the equinoxes in March and September, the Sun shines directly on the equator, giving us nearly equal amounts of day and night.
Why Is the September Equinox Special?
The September equinox is a turning point in the year. In the Northern Hemisphere, it signals the shift from the warmth of summer to the cooler, cozier days of autumn. For those in the Southern Hemisphere, it marks the beginning of spring, with longer days and blooming landscapes ahead. This dual significance makes the equinox a moment celebrated in many cultures around the world.
At the moment of the equinox, the Sun will have a right ascension of almost exactly 12 hours, positioning it nearly opposite where it was during the March equinox. This isn’t just a symbolic transition—it’s a precise event that can be measured in the sky.
How to Experience the Equinox
While the equinox itself isn’t a visual spectacle like an eclipse, there are still beautiful ways to connect with this moment:
- Sunrise and Sunset: One of the simplest yet most profound ways to observe the equinox is by watching the sunrise or sunset. On September 22nd, the Sun will rise due east and set due west. Find a spot with a clear view of the horizon and enjoy the rare sight of the Sun perfectly aligning with these cardinal points.
- Northern Hemisphere: In the Northern Hemisphere, this is the perfect time to soak in the early signs of autumn. Notice the changing leaves, the cooler breezes, and the soft, golden light that marks the season.
- Southern Hemisphere: For those in the Southern Hemisphere, the equinox ushers in spring. The days will get longer, and the world will start to bloom with new life and color.
The Sun’s Position at the Equinox
At the exact moment of the equinox, the Sun will be positioned at:
- Right Ascension: 11h 58m
- Declination: 0° 08' N
- Constellation: Virgo
- Angular Size: 31'52"
This places the Sun just above the celestial equator, perfectly balanced in the sky.
Tips for Enjoying the Equinox
Here’s how to make the most of this special day:
- Sun Observation: If you’re interested in safely observing the Sun, use a solar filter for your telescope. This lets you see the Sun without harming your eyes.
- Photography: The equinox is a great opportunity for photography, especially at sunrise or sunset. The balanced light can make for stunning landscape photos, with the Sun aligned due east or west.
- Skywatching: As night falls, take advantage of the longer nights to observe the stars. The equinox is a great time to explore autumn constellations in the Northern Hemisphere or spring constellations in the Southern Hemisphere.
What to Expect
Clear skies will make your equinox experience even better, especially if you’re planning to watch the sunrise or sunset. Check the weather forecast and try to find a spot away from city lights for the best view. The equinox is all about subtle beauty, so take a moment to enjoy the balance of day and night as the seasons change.