- Moon–Venus Conjunction: Before dawn on Sept. 19, a razor-thin crescent moon pairs up extremely close with dazzling Venus and the bright star Regulus in Leo earthsky.org. Skywatchers in parts of Europe, Africa, and the far northern Atlantic even get to see the Moon eclipse (occult) Venus around 12:00 UTC earthsky.org – a rare treat as the moon “takes a bite” out of the Morning Star! By Sept. 20’s dawn, the ultra-thin Moon (just ~3% illuminated) will sit below Venus and Regulus, still forming a pretty triangle in the east earthsky.org.
- Saturn Super Bright: The ringed planet Saturn reaches opposition on the night of Sept. 20–21, meaning Earth is directly between Saturn and the Sun. Saturn is at its closest and brightest of 2025, shining a golden magnitude 0.6 all night space.com – you can spot it easily by eye below the Pisces constellation. “Saturn will be visible with just your eyes in the night sky, but with a small telescope, you might be able to see its rings!” NASA encourages science.nasa.gov.
- Dark Skies & New Moon: Nights are extra dark this weekend – perfect for stargazing – because the Moon is a waning crescent only ~7% (Sept. 19) to 3% (Sept. 20) lit predicalendar.com predicalendar.com and rises just before sunrise. The New Moon arrives Sept. 21 (at 19:54 UTC) earthsky.org, which will even bring a partial solar eclipse for a few lucky observers in New Zealand, parts of Australia, and Antarctica (up to 79% of the Sun will be covered at sunrise in New Zealand) space.com. For the rest of us, the upside is moonless nights now – ideal conditions to see faint stars, the Milky Way, and any auroras.
- Planets on Parade:Venus blazes at magnitude –3.9 in the eastern pre-dawn sky, rising about 2–3 hours before sunrise space.com. Just above Venus, Jupiter (magnitude –2.1) rises in the late night and dominates the high morning sky space.com – binoculars reveal its four Galilean moons, and even a small telescope shows Jupiter’s cloud bands space.com. Mars is technically still visible after sunset, but it’s very low and faint in the west and getting lost in twilight space.com. (Mercury is out of view, having passed behind the Sun on Sept. 13 space.com.) In telescopes, Neptune (magnitude ~7.8) sits just 2° east of Saturn and reaches its own opposition on Sept. 23 space.com – a fun challenge object if you have optics.
- Meteor Watch: No major meteor showers peak on these dates – we’re between the big summer Perseids and the upcoming October Draconids earthsky.org. However, a couple of minor meteor streams linger. The tail end of the September Epsilon Perseids is active through Sept. 21 imo.net, though only producing ~1 meteor per hour now imo.net. Also, the mysterious Chi Cygnids had a possible burst around Sept. 14–16 imo.net; by this weekend any activity will be very low. Sporadic meteors (random “shooting stars” not from a named shower) still occur ~8–10 per hour before dawn under dark skies imo.net. With the late-rising crescent moon, you might catch a handful of these streaks each hour if you’re far from city lights.
- Aurora & Space Weather Alerts: The Sun is growing more active as it approaches its 11-year solar maximum. “The Sun is slowly waking up,” says NASA heliophysicist Jamie Jasinski, noting a surprise trend of increasing solar activity after a decades-long lull nasa.gov nasa.gov. Just last week (Sept. 14–16), a “hidden” solar wind blast sparked a G3 geomagnetic storm that brought Northern Lights sightings as far south as the U.S. Midwest foxweather.com forbes.com. For Sept. 19–20, forecasters expect quieter conditions – NOAA’s 3-day outlook shows the planetary K-index peaking around a moderate 3–4 (below official storm levels) spaceweather.gov. In fact, the probability of significant geomagnetic unrest this weekend is only ~10% at mid-latitudes spaceweather.com, though high-latitude areas (Alaska, Canada, Scandinavia) have up to ~20% chance of minor auroral storms spaceweather.com. Bottom line: No guaranteed aurora outbreak, but high-latitude observers under clear dark skies should remain alert for faint auroral glows on the horizon.
- Equinox Aurora Boost: Keep in mind we’re near the autumnal equinox (Sept. 22), a time when Earth’s tilt helps even small solar disturbances ignite auroras. Space weather experts point to the Russell–McPherron effect – around equinox, cracks can open in Earth’s magnetic field, enhancing auroras from even minor solar wind gusts spaceweather.com. In fact, a co-rotating interaction region (CIR) in the Sun’s wind is due by Sept. 22, which could be “perfect timing” to produce a geomagnetic display as fall begins spaceweather.com. So if you’re in northern-tier locations, keep watch on the night of 9/20 and especially 9/21–22 for any sudden green glows – and sign up for aurora alerts if you don’t want to miss a potential show spaceweather.com.
- International Space Station Flyovers: Don’t forget to wave to the ISS! The station continues to make predawn passes over many regions this month. It appears as a fast-moving “star” gliding across the sky for a few minutes. In fact, the ISS is the third-brightest object in the night sky (after the Sun and Moon) and easily visible even from cities if you know when to look theguardian.com. For example, around 5:30–6:00 am local time this weekend, early risers in central Europe can catch the ISS sailing west-to-east. (Exact viewing times vary by location; NASA’s handy Spot the Station tool can email you when the ISS will be overhead theguardian.com.) It’s always a thrill to see this house-sized spacecraft, with astronauts aboard, shining by reflected sunlight as it orbits ~400 km above Earth at 28,000 km/h.
In-Depth: This Weekend’s Celestial Highlights (Sept. 19–20, 2025)
1. A Dazzling Dawn Conjunction (Moon, Venus & Regulus) – Sept. 19 & 20
If you’re up early, look east before sunrise on Friday, Sept. 19. You’ll be rewarded with a gorgeous trio of celestial objects clustered together in the growing dawn light earthsky.org. The crescent Moon, just 27 days old and barely 7% illuminated, will hover right above brilliant Venus (the brightest “star” in the sky at that hour) predicalendar.com earthsky.org. Just adjacent to Venus you’ll spot Regulus, the blue-white heart of the Leo constellation. NASA calls it “a magnificent conjunction” – these three will appear side-by-side, though of course they’re actually far apart in space science.nasa.gov. It’s a striking visual alignment: picture Venus as a “jewel” and the slim Moon as a curved backdrop, with Regulus adding a spark of starlight.
In North America and most of the world, the Moon will sit a few degrees away from Venus (still very close – they’ll fit in a binocular field together space.com). However, in certain locations the alignment is so exact that the Moon will cover Venus. Skywatchers in extreme northeastern Canada, Greenland, Iceland, Ireland, the U.K., and parts of western Europe and North Africa get to witness a lunar occultation of Venus in broad daylight on the 19th space.com. Essentially, the bright planet will vanish behind the dark edge of the Moon for a short time – a rare and dramatic event if you have a telescope or even binoculars ( never point them near the Sun without precautions!). For some in western Russia and the Urals, the Moon will instead occult Regulus space.com. These “cosmic hide-and-seek” events underscore how precisely the orbital paths can line up.
Even if you’re not in the occultation zones, don’t miss the view. EarthSky.org encourages using binoculars on September 19’s dawn to fully appreciate the delicate scene: “There’s a beautiful sky scene waiting… a thin waning crescent moon very close to brilliant Venus, with the star Regulus nearby.” earthsky.org. Many astro-photographers will be out capturing the Moon and Venus pairing against the twilight – it’s that pretty.
By the next morning (Sat. Sept. 20), the Moon will have slid roughly 12° southeast (toward the Sun) in the sky, now a barely-there sliver (~3% lit predicalendar.com). Around 40 minutes before sunrise, look for that “old Moon” hanging below Venus and Regulus, forming a flattened triangle low on the eastern horizon earthsky.org. Venus remains unmistakable, outshining everything else at magnitude –3.9. This will be the Moon’s final appearance before it turns new – by Sunday it’ll be lost in the Sun’s glare. So enjoy this graceful celestial choreography while you can. It’s a fitting cosmic send-off to summer, as the autumn equinox looms just two days later.
2. Saturn at Opposition – The Ringed Planet Rules the Night
Move over, Venus – Saturn takes center stage after dark! This weekend, Saturn reaches opposition (exactly opposite the Sun in our sky) on the night of Sept. 20–21. For skywatchers, opposition is when a planet is closest to Earth and shines at its brightest. Indeed, Saturn now gleams at its peak magnitude of about +0.62 – the brightest it will get in all of 2025 space.com space.com. It rises around sunset, is highest around midnight, and sets near sunrise space.com, meaning you have all night to admire it.
Look for a golden-white “star” low in the east after dusk on Sept. 19 and 20. That’s Saturn, sitting among the faint stars of western Pisces. (If you’re unsure, note that Saturn doesn’t twinkle as much as true stars do.) By midnight it will be high in the south, a beautiful sight for anyone scanning the sky. At opposition, “Saturn will be at a distance of 794.7 million miles (1.278 billion km) from Earth” space.com – so it’s about as near as it gets. Of course, “near” is relative for an outer planet – Saturn is still 71 light-minutes away even at this close approach space.com!
Even with the naked eye, you’re seeing something special: sunlight is hitting Saturn square-on and reflecting straight back toward us. This causes the Seeliger effect, a surge in brightness due to Saturn’s famous rings. Essentially, the rings’ icy particles act like tiny mirrors when the Sun-Earth geometry is just right, backscattering extra light our way space.com space.com. So Saturn appears a bit brighter than it otherwise would. In fact, its rings themselves brighten dramatically for a few days around opposition – a phenomenon skywatchers with telescopes notice as the rings seem to “flash” a little more brilliantly.
And yes, telescopes! While Saturn is lovely to the unaided eye, it’s through a telescope that the real magic happens. Even a small backyard scope at 30× or higher will reveal Saturn’s iconic rings encircling the planet (currently appearing as a thin oval, since we’re seeing the rings at a shallow 2° tilt this year earthsky.org space.com). You might also glimpse Titan, Saturn’s largest moon, as a tiny pinpoint nearby. EarthSky’s editors gush that this is the “best viewing of Saturn in 2025” – don’t miss it earthsky.org. Saturn’s disk is ~19 arcseconds wide now, and the rings span ~45 arcseconds across space.com, so at moderate magnification you’ll discern the ring system and the dark gap (Cassini Division) on good nights. “Saturn will be putting on an out-of-this-world performance this month,” NASA teased in its monthly sky guide science.nasa.gov.
Fun fact: about every 15 years, Saturn’s rings align edge-on from Earth’s perspective, allowing its moons to cast noticeable shadows on the planet. We’re in such a period now (the rings were edge-on in 2025 March) space.com. That means this opposition is one of the last chances to see something cool: Titan’s shadow crossing Saturn. In fact, late on Sept. 19 (Friday night) for the Americas, advanced observers with larger telescopes were able to watch Titan’s tiny black shadow glide across Saturn’s cloud tops space.com space.com – the final such transit until the 2040s! While that specific event is past as of the 20th, Saturn’s other moons will continue to play shadow-games. If you have a big scope, keep an eye out for any dots or specks near Saturn – those are its moons (Titan, Rhea, Tethys, etc.), and occasionally you might see one disappear into eclipse or cast a shadow on Saturn’s globe, thanks to the current ring alignment space.com.
Overall, Saturn is a must-see this weekend. Whether with a telescope or just binoculars, take a moment to appreciate that you’re looking at a giant world 9 times Earth’s diameter, adorned with majestic rings – a true jewel of the solar system, now at its most welcoming. As NASA notes, “Saturn will be at its closest and brightest all year!” science.nasa.gov – so step outside and say hello to the ringed planet while it’s on show.
3. Moon Phase & Viewing Conditions – Waning Crescent & Equinox Sun
One big advantage for skywatchers on Sept. 19–20 is the Moon’s cooperative phase. We are in the final days of the lunar cycle, with the Moon a waning crescent only 27–28 days old. On Friday the 19th the Moon is just 7% illuminated, and by Saturday the 20th it’s a mere 3% sliver predicalendar.com predicalendar.com – essentially a thin arc in the pre-dawn sky. It rises very late (after 4am local time) and is completely absent during the evening and first half of the night. The result? Wonderfully dark skies all night long for weekend stargazers. Faint stars, nebulae, and the Milky Way band will pop out much more clearly without moonlight. If you’re a deep-sky observer or astrophotographer, this is prime time for targets like galaxies and dim clusters. And it’s no coincidence that major astronomy events (like this weekend’s conjunction and Saturn viewing) often fall near the new moon – it’s intentional, to maximize visibility.
The official New Moon occurs on Sept. 21 at 19:54 UTC earthsky.org (which is late afternoon on the 21st in Europe/America). Normally new moons themselves aren’t observable – the Moon is roughly between Earth and Sun and its dark side faces us. But this particular new moon brings an extra celestial event: a partial solar eclipse. Because the Moon will line up just slightly north of the Sun, it will cast a shadow that grazes Earth’s southern hemisphere on Sept. 21 (Sept. 22 local date in some areas). Only about 0.2% of the world’s population is in the eclipse zone space.com – mainly in a slice of the South Pacific. If you happen to be in New Zealand, mark the morning of Sept. 22: at sunrise, up to 79% of the Sun will be eclipsed by the Moon in the deep south of NZ space.com (e.g. Dunedin sees the Sun rise as a crescent!). Portions of eastern Australia (e.g. parts of Tasmania’s coast), Fiji, Samoa, and western Antarctica also get a partial eclipse around their sunrise/sunset space.com space.com. For the rest of us, this eclipse isn’t directly visible, but Space.com will host live webcasts space.com – and it’s a neat reminder that the Moon’s orbit is bringing it in line with the Sun.
Even if you can’t see the solar eclipse, everyone experiences the equinox on Sept. 22. This weekend basically straddles the change of seasons: Monday the 22nd at 18:19 UTC is the September equinox earthsky.org, marking the start of autumn in the Northern Hemisphere (spring in the Southern Hemisphere). Around the equinox, the Sun rises directly due east and sets due west for all observers space.com, and day/night are nearly equal length (about 12 hours each) space.com. One fun consequence: in cities with a uniform street grid oriented east-west, the equinox Sun aligns with the streets at sunrise or sunset – creating an “urban Stonehenge” effect. In Chicago, for instance, observers can watch the Sun framed perfectly between downtown skyscrapers along east-west streets, a phenomenon nicknamed “Chicagohenge,” which is visible on the days surrounding the equinox (roughly Sept. 19–22 just after sunrise and just before sunset) adlerplanetarium.org. If you live in a city, try looking down a straight east-west road at sunset this weekend – you might catch your own local version of this beautiful alignment.
In short, the astronomical conditions on Sept. 19–20 are excellent: dark nights, minimal moonlight, and mild late-summer weather (for much of the mid-latitudes) should make skywatching enjoyable. Just be sure to find a dark-sky location if you can – even heading to a local park or countryside spot will dramatically increase what you can see. The Milky Way is still a gorgeous river of light overhead on September evenings, stretching from Sagittarius in the southwest up through Cygnus overhead and down to Cassiopeia in the northeast. Take advantage of the moonless window to soak in those billions of distant stars.
4. Planetary Lineup: Venus & Jupiter in the Morning, Mars at Dusk
We’ve highlighted Venus at dawn and Saturn all night, but they’re not the only planets out. Here’s a quick tour of the other visible planets during Sept. 19–20 and how to spot them:
- Jupiter – The king of planets rises in late evening (around 11 pm local time on Sept. 19, and earlier each night) and by the wee hours it’s shining high in the east. Jupiter is extremely bright (about –2.2 magnitude now) – outshone only by Venus and the Moon – so it’s unmistakable once it’s up space.com. In the pre-dawn hours, Jupiter and Venus share the eastern sky, making a striking pair of “morning stars.” Through binoculars, you can usually spot Jupiter’s four largest moons in a line on either side of the planet space.com. With a telescope, you’ll see Jupiter’s cloud belts, and maybe even the Great Red Spot if it’s facing us (it rotates into view every 10 hours or so) space.com. On Sept. 16–17 the waning crescent Moon passed near Jupiter space.com, so by this weekend the Moon is out of the way – leaving Jupiter to rule the late night solo.
- Venus – As discussed, Venus is now a morning “star”. After spending much of the summer in the evening sky, Venus swung between Earth and Sun (inferior conjunction) in August and emerged as a brilliant morning beacon. In September it rises about 3 hours before sunrise at the start of the month and about 2 hours before by month’s end space.com. On Sept. 19–20, Venus rises roughly around 4:30–5:00 am local time (for mid-northern latitudes) and gleams low in the east until sky brightens. It’s hard to miss: Venus is the brightest object in the sky after the Sun and Moon. EarthSky notes that Venus sits in the constellation Cancer early in the month and then glides into Leo by Sept. 10 space.com. Right now it’s near Regulus (Leo’s brightest star) – hence the lovely conjunction with the Moon we described. Through a telescope, Venus appears as a tiny gibbous disk (about ~90% sunlit) because it’s on the far side of its orbit relative to Earth space.com. It will shrink in apparent size and wax toward full phase over the coming weeks, but also sink closer to the horizon each morning. So enjoy Venus now while it’s still high enough for good viewing.
- Mars – The red planet is pretty elusive at the moment. Mars is far on the opposite side of the Sun from us (it was at solar conjunction in mid-November 2024), so it’s faint and distant. In September 2025, Mars lingers very low in the western sky after sunset, moving through Virgo space.com. It’s only magnitude +1.8 – not very bright – and sets shortly after dusk. If you want to try, use the first stars appearing at twilight as your guide: Mars will be a tiny ruddy point low near the horizon, roughly in the vicinity of the bright star Spica (Virgo’s alpha star). In fact, Mars passed just 2° north of Spica on Sept. 12 space.com, so it’s still nearby. By about 7:30–8:00 pm local time, Mars will likely have sunk below the horizon. Given its low altitude and city skyline obstructions, many casual observers won’t catch Mars now. It’ll re-emerge in better view in the morning sky by early next year, ahead of its next opposition in late 2025. So unless you have a clear view and know exactly where to look, Mars might be a miss this month (don’t worry, Saturn and Jupiter are far more impressive right now).
- Mercury – Sorry, Mercury fans: you’re out of luck this month. Mercury is not visible at all in mid/late September space.com. It reached superior conjunction (passing around the far side of the Sun) on Sept. 13 space.com, and it’s still too close to the Sun’s glare. It will eventually emerge in the evening sky by October. So skip Mercury for now.
- Outer Planets (Uranus & Neptune) – For completeness: Neptune is at opposition just two days after Saturn (Sept. 23) space.com. Neptune lies in Aquarius, only about 8.5° east of Saturn currently space.com. At magnitude 7.8, Neptune is telescope-only, though keen-eyed folks under very dark skies might glimpse it with binoculars if they know exactly where to look. It appears as a tiny bluish “star” – but if you have even a modest telescope (3-4 inches or larger) at high power, you can distinguish Neptune’s tiny disk (around 2.4″ across) space.com space.com. You might also see its moon Triton (mag ~14) in larger scopes. Uranus (mag ~5.7) is higher up in Aries, rising later in the night. It’s technically visible to the naked eye from very dark sites, but binoculars will easily show it as a dim greenish dot. Uranus is not at opposition until November, but it’s already up by midnight and can be found near the Pleiades cluster in Taurus space.com. Again, these two giants require more effort and aren’t “must-see” for casual observers, but if you’re feeling adventurous and have optical aid, this weekend offers moonless nights to hunt them down.
5. Meteor Showers: Quiet, with a Chance of Sporadics
The mid-September period is relatively calm for meteors. We’re past the summer Perseids (August) and not yet at the fall Orionids (late October). No major annual shower peaks on September 19–20. That said, the sky is dark and Earth is still plowing through various sparse debris streams, so some minor activity is present:
- The September Epsilon Perseids (SPE) – an obscure shower – run from about Sept. 5 to 21, peaking on the 9th imo.net. Earlier this month there was a small outburst reported (some years SPE has surprised observers), but nothing huge this year. By the 19th, this shower’s rate is very low, maybe ~1 meteor per hour at best under dark sky imo.net. These meteors, if you see any, would appear to radiate from the constellation Perseus in the pre-dawn hours.
- The Anthelion source (ANT) – This is not a single shower, but a broad region of minor meteor activity that the International Meteor Organization tracks. It’s basically a constant trickle of meteors that seem to radiate from near the ecliptic opposite the Sun (hence “anthelion”). In mid-September the anthelion radiant is in Pisces, near Saturn’s location actually imo.net. It produces about 2 meteors per hour consistently imo.net, regardless of location. These are medium-speed meteors.
- The Chi Cygnids (CCY) – This is an interesting one. Discovered only in 2015 during a surprise burst, the Chi Cygnids are a possible shower that occasionally flares up around mid-September. In 2025, astronomers advised keeping watch on Sept. 14–16 in case of another mini-outburst imo.net. Indeed, around Sept. 15 a short-lived flurry was recorded with Kp6 auroras (some CCY meteors might have coincided with the solar storm) foxweather.com. However, if you missed it, you probably won’t see any CCY meteors now – expected rates after the 16th drop back to essentially zero. The Chi Cygnids are really more of a scientific curiosity at this point; they might not produce anything noticeable again for years, but observers monitor just in case.
- Sporadics: Aside from formal “showers,” the majority of meteors on any given night are sporadics, which are random background meteors not belonging to a known comet stream. Under truly dark skies, an observer at mid-northern latitudes can expect roughly 8–10 sporadic meteors per hour before dawn this time of year imo.net. In the first half of the night, rates are lower (perhaps 3–5 per hour) imo.net. Sporadics can appear anywhere in the sky, though they often long trails since they skim in at shallow angles.
In sum, don’t expect a meteor storm – but if you’re out late (or up pre-dawn for the Venus conjunction or aurora hunting), keep an eye out for the odd shooting star zipping by. The lack of moonlight will make even faint meteors more visible. Pro tip: lie back in a reclining chair so you can comfortably watch a large expanse of sky. If you’re lucky, you might catch a bright one! And remember, the next big meteor shower is the Draconids in early October (peak around Oct. 8, though often modest) earthsky.org and then the Orionids later in October earthsky.org. Until then, enjoy the peace and quiet of the September sky.
6. Aurora Outlook: Sun Wakes Up, Northern Lights Possibilities
Aurora borealis fans have had a lot to talk about this month. We are currently approaching the peak of Solar Cycle 25, and the Sun has been flexing its muscles. In fact, a new NASA study just confirmed that after a long stretch of declining activity, “the Sun reversed course and started to become increasingly active” around 2008 nasa.gov nasa.gov – a trend that’s continuing now. This has led to more frequent solar flares and coronal mass ejections (CMEs) that can trigger geomagnetic storms at Earth nasa.gov nasa.gov. Jamie Jasinski, lead author of the NASA study, noted that scientists were surprised by this uptick: “All signs were pointing to the Sun going into a prolonged phase of low activity… so it was a surprise to see that trend reversed. The Sun is slowly waking up.” nasa.gov nasa.gov. For skywatchers, a “waking” Sun means more chances for auroras, especially at high latitudes.
And indeed, mid-September delivered: On Sept. 12–13, a large “butterfly-shaped” coronal hole on the Sun’s surface sent a high-speed solar wind stream our way space.com. The result was a stronger-than-expected G3 geomagnetic storm on Sept. 14–15 (Kp index hit 7) space.com forbes.com. Skies exploded with auroras across Canada, Northern Europe, and even dipping into U.S. states like Michigan and Wisconsin (where green and red auroral arcs thrilled skywatchers) foxweather.com. If you saw stunning northern lights photos in the news recently, that’s what it was from. This shows how quickly conditions can change – a “surprise” solar disturbance can spark auroras far from the poles.
Now, for Sept. 19–20 specifically, the space-weather forecast is relatively calm. The NOAA Space Weather Prediction Center’s 3-Day Outlook indicates only minor geomagnetic activity: Kp values in the 2–4 range (quiet to unsettled) spaceweather.gov. No official geomagnetic storm watch is in effect for this weekend, meaning auroras will likely be confined to high latitudes under normal “quiet” auroral ovals. In concrete terms, that suggests:
- High latitudes (e.g. northern Scandinavia, Iceland, northern Canada, Alaska) – you may see some quiet aurora bands or glows overhead, especially around local midnight. NOAA gives roughly a 15–20% chance of active (Kp4) or minor storm (Kp5) conditions at high latitudes each day spaceweather.com spaceweather.com, even without a big solar event, simply because the auroral oval is usually present near the poles.
- Mid-latitudes (e.g. northern U.S., central Europe, U.K.) – chances of aurora are much lower this weekend, maybe ~1%–5% unless a surprise solar flare/CME occurs. NOAA estimates only ~10% chance of even “active” geomagnetic conditions at mid-latitudes in the next 48 hours spaceweather.com. So it’s unlikely folks in, say, Germany or the northern U.S. will see auroras on 19–20 under the current forecast.
However – stay flexible. The Sun can always throw a curveball. Interestingly, spaceweather forecasters are eyeing Sept. 22, right at the equinox, when a co-rotating interaction region (CIR) – basically a shock front where slow and fast solar wind streams collide – is expected to brush past Earth spaceweather.com. This is predicted to be a relatively small disturbance, but because of the equinox effect, even that could spark a geomagnetic unsettled spell or minor storm. The Russell–McPherron effect (named for the scientists who described it) basically means equinox times favor auroras – the way Earth’s magnetic field is oriented allows more solar particles to penetrate our magnetosphere spaceweather.com. As Spaceweather.com quipped, the timing is “perfect” – a little bump on Sept. 22 could translate into vivid auroras, even if the same solar wind in July might have done little spaceweather.com.
So our advice: if you live above, say, 50° N latitude (or far southern latitudes for the aurora australis), keep an eye on the aurora oval forecasts and Kp index this weekend into early next week. A Kp of 4–5 might mean auroras low on your northern horizon; Kp 6 or higher and you could get a full-sky display. There are many free aurora alert apps and services (including NOAA’s alerts, Spaceweather.com’s SMS service spaceweather.com, etc.) that can notify you if geomagnetic activity suddenly spikes. And of course, if you do venture out under clear skies at night, do a quick check to the north – you might notice a faint greenish glow or pillars and not even realize it’s the northern lights!
Overall, while no major aurora storm is expected on Sept. 19–20, the combination of a near-new Moon (dark sky) and the enhanced solar activity environment means it’s worth being aurora-aware. At high latitudes, you essentially have a standing aurora “alert” nightly. At lower latitudes, this weekend probably won’t bring anything unless the Sun surprises us – but the coming weeks around equinox often do bring some aurora excitement, so it’s a good time to stay tuned to space weather news.
7. Bonus: Spot the International Space Station (ISS)
Amid all these natural celestial delights, don’t overlook a human-made “star”: the International Space Station. The ISS is orbiting Earth every 90 minutes, and when conditions are right it appears as a bright, steady, fast-moving star gliding across the sky. Many people are amazed when they first see it – it’s very bright (often magnitude –3 to –4, rivaling Venus). In fact, the ISS is the third-brightest object in the sky, after the Sun and Moon theguardian.com. It’s brighter than any planet or star, thanks to its large reflective solar panels catching sunlight.
This weekend, the ISS’s orbit happens to favor predawn passes for many locations (it varies on a roughly 6-week cycle between evening and morning visibility). For example, across much of Europe the ISS will make a high pass in the early morning hours. In Warsaw, Poland (where it’s currently near equinox dawn), an ISS pass is expected on Sept. 20 around 5:20 am local time, moving west to east and reaching about 60° altitude – appearing as a swift white dot taking a few minutes to cross the sky. Similarly, in the northeastern US, the ISS has pre-dawn appearances around 5–6 am this week (exact times differ by city). To know when it flies over your area, you can use NASA’s “Spot the Station” service theguardian.com, which offers free email or text alerts for visible passes at your location. There are also smartphone apps and websites that track the ISS in real time.
When you see it, keep in mind: there are currently astronauts aboard that moving light! The ISS orbits about 420 km (260 miles) above us, traveling at 28,000 km/h. It often makes people pause in wonder, realizing our species has a continuously inhabited outpost in space that’s visible with the naked eye.
One tip: the ISS usually appears in the west or northwest, travels in an arc (due to Earth’s curvature) and disappears in the east or southeast, often fading as it enters Earth’s shadow (i.e. the sunrise terminator line). It does not blink (aircraft will have blinking lights; the ISS is steady). If you see a bright light moving silently across the stars over a few minutes, congratulations – you’ve spotted the space station.
So if you’re out predawn watching Venus and the Moon anyway, or checking for auroras, take a moment to scan for the ISS as well. It’s a nice reminder of the human presence in the sky amid all the natural celestial happenings.
The nights of September 19–20, 2025, are packed with skywatching goodness. From a spectacular Moon-Venus meeting at dawn, to Saturn’s once-a-year brilliance overnight, plus dark skies for deep-sky stargazing, this weekend has something for everyone. While meteor activity is low, the Sun’s heightened activity means aurora watchers should stay alert (especially up north), and even casual observers can enjoy knowing the ISS and maybe a few shooting stars are zipping overhead. As we transition into autumn, nature is putting on a fine celestial show – so grab a jacket, head outside, and look up! Clear skies and happy skywatching.
Sources: Skywatching highlights from NASA science.nasa.gov science.nasa.gov; EarthSky and Space.com observational guides earthsky.org space.com space.com; International Meteor Organization meteor outlook imo.net imo.net; NOAA Space Weather Prediction Center and Spaceweather.com data spaceweather.com spaceweather.com; NASA/Jet Propulsion Lab solar activity analysis nasa.gov nasa.gov; The Guardian (Royal Observatory) ISS spotting tips theguardian.com theguardian.com; Space.com and TimeandDate eclipse information space.com space.com.
