Night sky September 2026 brings a fascinating selection
of sights and events for UK observers. As the nights begin to draw in,
September offers two comets, two lunar occultations, the autumn equinox,
Neptune at opposition and plenty of opportunities to follow the planets
across the sky.
There are also plenty of opportunities to follow the planets as they
move through the September sky.
🔭 September at a Glance
- Comet 161P/Hartley–IRAS – brightening during September
- Comet 10P/Tempel 2 – challenging but worth looking for
- 8 September – the Moon occults the Beehive Cluster, M44
- 14 September – lunar occultation of Venus
- 23 September – autumn equinox
- 26 September – Neptune reaches opposition
The Comets of September
Two comets provide interesting challenges this month:
161P/Hartley–IRAS and 10P/Tempel 2.
Both can be observed with modest astronomical equipment under suitable
conditions, although a dark sky and a good star atlas or planetarium
application will make finding them considerably easier.
What do comet names mean?
A name such as 161P/Hartley–IRAS contains useful
information. The number identifies it among numbered periodic comets,
while the letter P tells us that it is a periodic
comet. The remainder of the name normally recognises the discoverer
or discoverers — in this case Hartley and the IRAS mission.
Comet 161P/Hartley–IRAS
Comet 161P/Hartley–IRAS provides an interesting target during September.
The comet was discovered in 1983 and carries the names of Malcolm Hartley
and IRAS, the Infrared Astronomical Satellite.
During the month it can be followed as it moves through
Eridanus and Cetus, continuing towards
Aquarius as we move towards early October.
For UK observers it remains relatively low in the sky, so finding a
location with a clear horizon will help.
At the beginning of September it is expected to be around magnitude
+12.1, brightening during the month towards approximately
+9.7.
One way to begin looking for it in early September is to locate
Tau Eridani and use a detailed star chart to follow the
comet’s movement towards Cetus.
Because a comet changes position against the background stars from one
night to another, this is an excellent object to return to repeatedly
during the month.
Comet 10P/Tempel 2
Our second comet is 10P/Tempel 2.
The number 10 tells us that it was the tenth periodic comet to receive a
permanent number, while the name honours astronomer
Wilhelm Tempel.
This is a difficult object for UK observers because it remains very low
in the sky. Under a clear, dark sky and with suitable equipment, however,
experienced observers may be able to follow it as it moves through
Piscis Austrinus.
Don’t be disappointed if you cannot find it. Low altitude means we are
looking through considerably more of Earth’s atmosphere, which can make
already faint objects much harder to see.
What Does Magnitude Mean?
Astronomers use magnitude to describe how bright an
object appears. The scale can seem backwards at first:
the lower the magnitude number, the brighter the object.
An object at magnitude +1 is therefore much brighter than one at
magnitude +6. Particularly bright objects can even have negative
magnitudes.
8 September – The Moon Occults the Beehive Cluster
During the early morning of 8 September, the Moon passes
in front of the open star cluster M44, better known as
the Beehive Cluster, in the constellation Cancer.
This type of event is known as a lunar occultation.
From our viewpoint the much nearer Moon appears to pass in front of the
more distant stars.
For UK observers the event begins at around
04:00 BST (03:00 UT) and continues towards dawn.
As morning twilight increases, some of the cluster’s fainter stars will
become more difficult to see.
This could also provide an interesting photographic opportunity.
⚠️ Solar Safety Warning
Some of this month’s events occur during twilight or daylight when
the Sun may be above or close to the horizon.
Never sweep the sky with binoculars or a telescope when the
Sun is nearby. Accidentally allowing direct sunlight into
unfiltered binoculars, a telescope or finder scope can cause
permanent eye damage or blindness. If you cannot locate an object
safely, do not attempt the observation.
14 September – The Moon Occults Venus
Another unusual observing and photographic opportunity occurs on
14 September, when the Moon passes in front of
Venus.
This is a daylight event for UK observers, which makes it considerably
more challenging.
The precise disappearance and reappearance times vary according to your
location, so check an up-to-date astronomy application or occultation
prediction for where you live before attempting the observation.
Venus is extremely bright and can be seen through a telescope in
daylight under suitable conditions, but locating anything through optical
equipment when the Sun is above the horizon requires particular care.
If you are inexperienced with daytime telescope observing, it is better
to miss the event than risk accidentally pointing optical equipment
towards the Sun.
The Planets
Mercury
Mercury is poorly placed for UK observers during September and remains
too close to the Sun to make it a worthwhile observing target.
Venus
Venus is also poorly placed for conventional observing during much of
the month, although its occultation by the Moon on 14 September provides
one of September’s most unusual events.
Mars
Mars begins September in Gemini before moving into
Cancer later in the month.
On 6 and 7 September a waning crescent Moon lies nearby, creating an
attractive pairing.
Mars shines at around magnitude +1.2 during the month.
Jupiter
Jupiter is a morning planet during September and can be
found in Cancer.
A thin waning crescent Moon lies nearby on the mornings of
8 and 9 September, providing another attractive sight
for early risers.
Saturn
Saturn is another morning planet, shining at around magnitude
+0.5 at the beginning of September.
It is located around the Pisces/Cetus region during the month and becomes
increasingly well placed as September progresses.
Uranus
Uranus shines at approximately magnitude +5.7 in
Taurus.
Although technically close to the naked-eye limit under exceptionally
dark conditions, binoculars or a telescope and a good chart make finding
it considerably easier.
Neptune
Neptune reaches opposition on 26 September.
At opposition a planet lies opposite the Sun in our sky, meaning it rises
around sunset and remains visible for much of the night. This makes
opposition one of the best times to observe a distant planet.
Neptune is far too faint to see with the naked eye, so you’ll need
binoculars or, preferably, a telescope and a good star chart to identify it.
Moon Phases – September 2026
Following the Moon through its phases is one of the easiest ways to begin
regular observing.
- Last Quarter: 4 September
- New Moon: 11 September
- First Quarter: 18 September
- Full Moon: 26 September
If you’re interested in exploring the lunar surface in more detail, read
our Observing the Moon: A Beginner’s Guide.
And if you’d like to try imaging it yourself, our
How to Photograph the Moon: A Beginner’s Guide
takes you from a smartphone through to a camera and telescope.
23 September – The Autumn Equinox
September also marks the beginning of astronomical autumn in the Northern
Hemisphere.
The autumn equinox occurs on 23 September, when the Sun
crosses the celestial equator.
For observers in the UK, it also signals something astronomers have been
waiting for throughout the summer:
longer nights.
As September progresses, darkness arrives earlier and gives us more time
to explore the night sky.
Make the Most of the September Night Sky
There is plenty to discover in the night sky September 2026,
but you don’t have to observe everything in this guide.
Choose one or two events that interest you and make a note of their dates.
If you’re following one of the comets, try returning to it on several
nights and see whether you can detect its movement against the background
stars.
Or simply go outside on a clear September evening and see where the night
takes you.
That’s part of the pleasure of astronomy. You may go outside intending
to find one object and end up spending the evening looking at something
completely different.
Clear skies.
Observing information:
Astronomical event information for this article was prepared with
reference to the September 2026 issue of BBC Sky at Night Magazine.
Event visibility and precise timings can vary according to location and
observing conditions. Readers should check local predictions before
observing time-sensitive events.