The autumn night sky
As the leaves begin to fall from the trees, the summer constellations give way to those of the cooler months
Moving upwards, away from the summer constellations of Cygnus and below, the Milky Way begins to lose some of its lustre as it starts to thin out compared to the densely star-packed region around the galaxy’s centre. It is still impressive to see though, especially if you can get out to a dark-sky site in order to observe this shimmering belt of stars.
During autumn our Milky
Way moves through the constellations of Perseus, Cepheus (the King) and Cassiopeia (the Vain Queen).
Not all of the constellations of summer have disappeared though – the likes of Cygnus and Aquila are still on show, offering observers in the Northern Hemisphere a selection of summer nebulae and star clusters. Autumn is the time to seek out open star clusters in our galaxy, which glow extremely brightly like gems in the night sky.
Astronomy is best done under night skies untouched by light pollution and on a Moonless night, but if you’re an urban dweller who is unable to get out to the countryside, open clusters are still easily visible from locations of moderate town haze. Star clusters stand out much better than fuzzy and often dim nebulae. Not only that, but the Milky Way laces through constellations that are high up in the sky, meaning that you won’t need to peer through a horizon touched by artificial lighting in order to get a good look at our galaxy.
6 Messier 52
Constellation: Cassiopeia
Right Ascension: 23h 24m 48s Declination: +61° 35’ 36” Magnitude: +6.9
Minimum optical aid: 10x50 binoculars
This open cluster displays one of the biggest problems of the Milky Way. Because we’re looking into the galaxy’s spiral arms, which are full of dust, the light of objects in the Milky Way can be dimmed by that dust, which makes it hard to calculate their distance. Open cluster Messier 52 lies between 3,000 and 7,000 light years from us, but even though interstellar dust is blocking some of the light, it’s still an easy binocular object.
7 Messier 103
Constellation: Cassiopeia
Right Ascension: 01h 33m 20s Declination: +60° 42’ 00” Magnitude: +7.4
Minimum optical aid: Four-inch refractor or five-inch reflector
Another open cluster, Messier 103 contains about 40 stars, including a red giant, which is an evolved star reaching the end of its life. This is a very rare sight in an open cluster of young stars. To find M103, locate the bottom-left star of Cassiopeia’s
‘W’, called Ruchbah, or Delta Cassiopeiae, and the cluster is about a degree northeast.
8 Messier 34
Constellation: Perseus
Right Ascension: 02h 42m 10s Declination: +42° 46’ 00” Magnitude: +5.5
Minimum optical aid: 10x50 binoculars and four- or five-inch telescopes
If you look two binocular fields north of Algol, the brightest star in Perseus and a variable star, you’ll come across the open star cluster Messier 34. Binoculars will not resolve any of the 90 member stars, but if you direct a small four-inch telescope its way, the stars will start to pop out.
9 IC 1396
Constellation: Cepheus
Right Ascension: 21h 36m 23s Declination: +57° 19’ 59” Magnitude: +11.5
Minimum optical aid: CCD camera
In order to see IC 1396, a star-forming region that forms part of the Cepheus Bubble, you’ll need a CCD camera. Being incredibly faint, you would likely find it difficult to pick up this nebula and its darker regions, known as Bok globules, with binoculars or a telescope alone. Imaging IC 1396 will reveal a hot supergiant illuminating its centre and yellow supergiant Mu Cephei at its edge.
10 Little Dumbbell Nebula (Messier 76)
Constellation: Perseus
Right Ascension: 01h 42m 24s Declination: +54° 34’ 31” Magnitude: +10.1
Minimum optical aid: Six to eight-inch telescopes
Taking on an appearance similar to that of the Dumbbell Nebula, Messier 27, the pint-sized Little Dumbbell Nebula will require a telescope of at least six inches for comfortable observing. Point your instrument to Phi Andromedae, a prominent blue star, then look slightly east and you will come across the nebula.
11 Capella (Alpha Aurigae)
Constellation: Auriga
Right Ascension: 05h 16m 41s Declination: +45° 59’ 53” Magnitude: +0.08
Minimum optical aid: Naked eye
It’s not too difficult to find the rich, yellow-white star Capella, the sixth-brightest star in the sky, in the constellation of Auriga (the Charioteer). Capella is actually a star system of four stars, which can easily be split into two stars. The yellowish tint of this star is much more apparent in a daytime sky with its contrast against the blue.