5 star clusters to see with the naked eye

You don't always need a telescope or binoculars to see beautiful star clusters in the night sky. Here are our top 5 open clusters visible with the naked eye.

5 star clusters to see with the naked eye. Credit: Bryce Crage / Getty Images

Most of us think of the deep sky as the neighbourhood of telescopes and binoculars. It’s hard to imagine the things astronomers have learned about the Universe and the photos of galaxies captured by high end telescopes being possible without them.

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But that doesn’t mean we have to be left out if we want to see beautiful star clusters without using lenses.

Naked-eye astronomy is nothing new: as far back as ancient times, long before the invention of telescopes, people have observed deep-sky objects with just the naked eye.

The Pleiades can be found by tracing the three stars of Orion's belt and following the line they create to find what appears as a 'smudge' in the night sky. Credit: Tommy Nawratil / CCDGuide.com
The Pleiades can be found by tracing the three stars of Orion’s belt and following the line they create to find what appears as a ‘smudge’ in the night sky. Credit: Tommy Nawratil / CCDGuide.com

Two of the most famous naked-eye clusters in the night sky are the Hyades and Pleiades clusters of Taurus the bull, but there are others you can see just by looking up.

Here are 5 other open clusters – gravitationally bound but loose groupings of stars – that I love, and which you can see without any kind of optical aid.

To help your eyes prepare for observing the night sky, read our guide to averted vision. And if you need help locating our 5 clusters, you can use free planetarium software like Stellarium or download an astronomy app to your smartphone. But don’t forget to turn your phone’s screen red to help preserve your night vision.

I hope you’ll head out tonight and have a look. Happy hunting and clear skies!

5 naked-eye star clusters

1

Ursa Major

The Plough / Ursa Major. Credit: Christophe Lehenaff / Getty Images
Credit: Christophe Lehenaff / Getty Images

Let’s start with one of the most famous patterns in the night sky. The Plough is an asterism, an unofficial group of stars within Ursa Major.

While most of the patterns we see are made up of unrelated stars, most of the Plough’s stars are at about the same distance and are moving away from us at about the same speed and in the same direction.

The Ursa Major Moving Group is probably the closest cluster to us, only about 80 lightyears away and is so spread out in our sky that you probably didn’t realise you were looking at a cluster at all.

It’s circumpolar, which means it’s so far toward the north that it’s in the sky every night of the year. You probably already know how to find it, so just look to the north the next time you’re looking up.

For more Plough observing, read our guides on stars Merak and Mizar and Alcor.

2

Coma Berenices Star Cluster

The Coma Star Cluster, photographed by astronaut Donald R. Pettit onboard the International Space Station. Credit: NASA/Donald R. Pettit
The Coma Star Cluster, photographed by astronaut Donald R. Pettit onboard the International Space Station. Credit: NASA/Donald R. Pettit

The beautiful Coma Star Cluster is tucked about halfway between the Alkaid, the last star in the Plough’s handle and Denebola, the tail of the constellation Leo, the lion.

It’s a group of 50 or so stars, located about 300 light years distant. It’s a little tough under light pollution but it’s best seen on spring nights, once all of Leo is high enough into the eastern sky to see easily.

3

Orion’s Head

Collider 69 is located in the Orion constellation. Credit: Yu-Hang Kuo
Collider 69 is located in the Orion constellation. Credit: Yu-Hang Kuo

Lots of us can quickly rattle off the names of Orion’s most famous stars – his shoulders, feet, and three belt stars – but what about his head? Meissa is the brightest star in Collinder 69, a small cluster around 1000 light years away.

With the naked eye, you should be able to see it in a triangle above Betelgeuse and Bellatrix, the hunter’s shoulders on clear nights from October to May.

You might even be able to pick out a small backward-L-shaped group made from some of the cluster’s other stars.

4

Alpha Persei Cluster

Open cluster Melotte 20, or the the Alpha Persei Cluster. Credit: Martin Gembec (http://astrofotky.cz/~MaG)
Open cluster Melotte 20, or the the Alpha Persei Cluster. Credit: Martin Gembec (http://astrofotky.cz/~MaG)

One of my favorite non-Pleiades clusters is the wonderful Alpha Persei cluster, which is about 600 lightyears away. Mirfak, the brightest star in the constellation is also the brightest in the cluster.

It’s easiest to see from late summer and into autumn, but Perseus is circumpolar in the UK, so it’s above the horizon every night of the year, though it dips frustratingly close to the northern horizon for much of the spring.

5

Double Cluster

NGC 884 & NGC 869 The Double Cluster Terry Hancock Fremont, Michigan Captured from Stephen Wessling Observatory, Fremont, Michigan Nov 9th 2015 Optics: Astro-Tech AT64 Quadruplet Refractor CCD: QHY23M Monochrome @ -20C Rainbow-Astro RST-400 EQ Mount Filters by Optolong Exposures 3 x 180 sec LRGB Total Integration time 36 minutes Pre Processed with CCDStack, Post Processed in CS6 Star Spikes Pro used for Star diffraction spikes Just going through some old data and I came across this one that I captured on NOV 9 of 2015 using an Astro-Tech AT65 Quad Astrograph that had been returned to the manufacturer as faulty and then sent to me for troubleshooting, this is only 3 x 180 seconds each LRGB and using Optolong Filters. I found no issues with it in fact I was very impressed with the optics, a perfect combination using the very sensitive QHY23 Mono CCD The Double Cluster in the constellation of Perseus lie very close to us at only 7500 light years and is one of the most popular targets in the Night Sky for amateur Astronomers and imagers, a perfect object for testing a refractor.
Credit: Terry Hancock

While we’re looking at Perseus, let’s try to find the Double Cluster, two open clusters (NGC 869 and NGC 884) that appear very close to each other in our sky. They’re about 7,500 lightyears away and appear to be about halfway between Mirfak and Cassiopeia’s W-shaped asterism.

These two are also in the far northern part of the sky so, like Ursa Major and the Alpha Persei Cluster, they’re circumpolar and are in the sky every night of the year.

What are your favourite naked-eye star clusters? Let us know by emailing contactus@skyatnightmagazine.com.

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Scott Levine is a naked-eye observer and writer based in New York’s Hudson Valley. For more stargazing tips, visit his website Scott’s Sky Watch.