From September to December, astronomers get the chance to view summer jewels, catch autumn gems at their finest and take the first glimpses of the delights of winter.
Thanks to a quirk of Earth’s axial tilt, as we approach the autumn equinox in the northern hemisphere the ever-lengthening nights bring astronomical summer delights to view earlier in the evenings, set against darker skies.
The glories of the Milky Way stay on view, giving us a chance to spot nebulae, clusters and the star clouds for that little bit longer.
As autumn enters into full swing, we get to look deep into space with galaxies and distant planets on show.
Milky Way delights
Early on in September we can still see the Milky Way stretching up across the sky, starting with the centre of our Galaxy almost due south at the end of twilight.
Here we have gorgeous summer objects such as the Lagoon Nebula (M8), the Trifid Nebula (M20) and the Omega Nebula (M17), while star clouds and clusters such as M24 and the Wild Duck Cluster (M11) cry out to be viewed.
An image of the Lagoon Nebula captured by the VLT Survey Telescope at ESO’s Paranal Observatory, Chile. Credit: ESO/VPHAS+ team
The Summer triangle
Higher up towards the zenith all three members of the Summer Triangle asterism – bright stars Deneb, Vega and Altair – remain on view well into December.
Bounded within this triangle is the stunning planetary nebulae the Dumbbell Nebula (M27) and the Ring Nebula (M57).
If you enjoy double and multiple stars, Albireo in Cygnus should be on your observing list.
Its golden yellow and sky blue components are easily resolvable with a small telescope.
Engrossed in the splendours of our Galaxy, it is easy to overlook dark nebulae.
Look along the Milky Way towards Cygnus and note the split in the Milky Way.
This is the Cygnus Rift; a huge cloud of interstellar dust obscuring our view of background stars.
Cosmic dust like this lies in the plane of our Galaxy and so gives rise to many dark patches that are worth looking out for.
If you can pry your gaze from our Galaxy, take a look at the multitudes of globular clusters that surround it in a halo.
For us this extends from Scorpius up into Serpens, Ophiuchus, Hercules and down into Capricornus, Aquarius and Sagittarius.
These incredibly distant objects, several thousand lightyears away, include such gems as M13 and M92 in Hercules, M5 in Serpens, and M22 and M28 in Sagittarius.
In small telescopes they often look like little cotton balls.
A view of M92, as seen by the Hubble Space Telescope. Credit: en:NASA, en:STScI, en:WikiSky – en:WikiSky’s snapshot tool
Approaching the end of autumn
As we move into October and November, the constellations of Aquarius and Capricornus become better placed over in the south, rich with promising targets.
Pick off the final batch of globular clusters such as M30, M2 and M72, along with M15 up in Pegasus.
Seek out the faint but large Helix Nebula and the Saturn Nebula, two planetary nebulae in Aquarius.
There are also two planetary interlopers coming into view at this time.
Neptune lies in Aquarius not too far from Lambda Aquarii, while Uranus is further along the ecliptic in Pisces and becoming better placed to view.
From October until the end of the year the final glories of the autumn skies come into view, taking us into the more distant reaches of space.
Pegasus has the often overlooked galaxy NGC 7331, while close by lies the more challenging Stephan’s Quintet of galaxies.
This is prime time for galaxies as Andromeda and Triangulum move into sight.
Pick a clear, transparent night, head to a dark sky area and let your eyes become properly dark adapted (it takes about 40 minutes) to stand the best chance of seeing their namesake galaxies, M31 and M33, the farthest objects it is possible to glimpse with the naked eye.
Finally, as we approach December, stunning Taurus and mighty Orion come into view for us to feast our eyes on, heralding the start of winter’s observing and the joys it promises.