It’s hard to follow up a month like August: every year it wows with the Perseids shower and a host of other astronomical events. But this year September does its best: the September night sky is full of interesting astronomical events.
This month you’ll be treated to a series of planet-gazing opportunities, a few other celestial objects, and of course the September equinox. Whether you’re new to stargazing or just seeking some of the other interesting astronomical sights (Neptune! 47 Tucanae!), there’s plenty to see in September.
Additionally, September signals a season change, from summer to autumn in the northern hemisphere and from winter to spring in the southern ones. This means your chances to see the aurora begin to shift hemispheres, and it’s the perfect time to plan your trip to see the northern lights for those in the northern hemisphere.
If you need a telescope to help enjoy this month’s night sky events, we have a guide to the best stargazing telescopes. From the Meade Polaris 130 (under $200) to the Orion Atlas 8 EQ-G GoTo ($2000), you can find one for your astronomy interest and budget.
Ready to learn more about what you can see in the September night sky this year? Read on for 12 of the most interesting astronomical events, conjunctions, and viewing opportunities in the night sky in September 2020.
Did you know? These are some of the best stargazing events this month – but there are many other interesting events and good nights for stargazing all year long.
Learn more and get your copy of The Night Sky in 2021: When to Go Stargazing All Year Long for just $5.99 (on sale from $7.99).
This post was originally published in August 2018, and was updated in August 2019 and August 2020.
Featured image credit: Lukas Schlagenhauf via Flickr
September 2: Venus at its Highest in the Morning
It’s always nice to see bright Venus in the sky; she oscillates between appearing in the mornings and evenings. Over the past few months, Venus has been low near the horizon and sun in the morning hours, but has been rising slowly but surely. On September 2nd our neighboring planet will reach its highest point in the morning sky, 41° above the horizon. Look east in the morning sky and you can’t miss it!
September 5: Close Approach of the Moon & Mars
On the night of September 5th, the Moon and Mars will appear almost on top of one another in the night sky – just 0°01′ apart – as they make a close approach. Unfortunately, the moon will be bright and nearly-full (85% illuminated), which will interfere with your ability to spot the red planet beyond. Nevertheless, it’s an interesting opportunity to see celestial bodies appear so close that they almost “touch.”
September 9: Peak of the ε-Perseid Meteor Shower
September is not known for its meteor showers. Even those do that occur have a hard time comparing to the show the Perseids put on in August. Still, any chance to spot them is worth trying if the skies are clear!
On September 9th, you can try to spot ε-Perseids meteors. Despite their name, these meteors are likely not caused by the same comet (109P/Swift-Tuttle) as the August Perseids; instead, they simply appear to radiate from the same point in the night sky – which is how meteor showers get their names.
At their maximum, you can look for roughly 5 ε-Perseids per hour, coming from the general area of the constellation Perseus high in the southwest sky. Like we said – not as spectacular as Perseids, but still interesting!
September 11: Neptune & Asteroid Fortuna at Opposition
If there’s one night to dig out and set up your telescope in September, let us put forward this contender. On September 11th you’ll have the chance to spot two cool solar system objects that are not visible to the un-aided eye.
Unlike Uranus which can be spotted under the most pristine dark sky conditions, ice giant Neptune can never be seen without some sort of magnification. So the fact that Neptune will be at Opposition on September 11th and well-lit by the sun makes it a great time to try and spot the distant planet. Neptune will be high in the southern sky, in the constellation Aquarius.
While you’re out there, try and spot Asteroid 19 Fortuna nearby in the constellation Pisces. While 19 Fortuna will reach opposition late in the night (near dawn), you can spend time looking for it in the evening sky while it is still at a good celestial position.
September 14: Close Approach of the Moon & Venus
As we move toward the new moon on September 17th, head out for a cool close approach between the Moon and Venus. On the night of 14th, bright Venus will appear within 4°21′ of the crescent waning Moon. It’ll be hard to miss the pair, and a great opportunity to try your hand at astrophotography!
September 17: 88P/Howell at its Brightest
The new moon is always a good reason to go at and stargaze. This month, it’s also another good opportunity to pull out your telescope. Comet 88P/Howell will appear at its brightest on the night of September 17th. On this night, the comet will be just 1.37 AU from earth – and an almost equidistant 1.36 AU from the sun. 88P/Howell will continue to approach the sun until September 26th when it reaches perihelion. From there, it will begin making its way away and dimming.
88P/Howell is best viewed from closer to the equator. Also note that unlike Comet NEOWISE that wowed us without needing a telescope, you will need some form of aid to try and spot 88P/Howell.
September 22: Mercury Reaches its Highest in the Evening
Like Venus earlier in the month, Mercury never appears high in the sky; those mornings and nights when it does are worth marking on your calendar to try and spot the small planet.
On September 22nd, Mercury will reach its highest point in the evening sky, just 10° above the horizon after the sun has set. You’ll need a clear view of the western horizon. This means no mountains, trees, or other obstructions, if you’re trying to spot Mercury as the night comes on.
September 22: September Equinox
On September 22nd this year, the seasons officially changed. The September Equinox – called the “autumnal equinox” in the northern hemisphere and the “vernal equinox” in the southern hemisphere – signals the point where earth experiences roughly equal lengths of day and night.
While there is no night sky event to view for the equinox, it’s a cool time to consider our planet’s place in the solar system and how we orbit around the sun.
September 25: Close Approach of the Moon, Jupiter & Saturn
Over the course of September 25th (the pre-dawn hours and the evening hours), you’ll have the chance to spot our solar system’s two gas giants in close proximity to a third-quarter moon. First Jupiter and then Saturn will make a close approach with the Moon; within 1°35′ and 2°18′ of each other, respectively.
Jupiter and Saturn will be quite obvious to spot; but Pluto is in the same area if you’ve got your telescope out. The moon will be 8 days old, so you will have some light pollution from it. (A good telescope will make it possible to spot this large dwarf planet.)
September 27: Globular Cluster 47 Tuc is Well-Placed
While you may not have heard of globular cluster 47 Tucanae, you may well have seen it. 47 Tuc – its nickname – is the second brightest globular cluster in the night sky, and visible across most of the planet – especially at lower latitudes and south of the equator.
On the night of September 27th, 47 Tuc will be well-placed for viewing, high in the sky depending on your location. 47 Tuc is home to some ten thousands stars in varying life stages, and appears at magnitude 4.1. This makes it easily visible to the unaided eye for intrepid stargazers looking for deep space objects.
Do you have questions or comments about these September night sky events? Let us know in the comments.