BINOCULAR TOUR

A collection of the night sky's most colourful objects, including one of its reddest

1. Psi Aquarii star field

Colourful star fields are a delight in binoculars and this one is particularly interesting. With the exception of class O, it contains bright stars of the main spectral classes (BAFGKM), so you can use it to get a sense of the colours of each class. Psi-2 (s-2) Aqr is a B, s-3 is an A, 83 and 96 are Fs, 94 is a G, s-1 is a K, and Chi (r) and Phi (q) are Ms. ! SEEN IT

2. Neptune 10x

50 Shining at mag. +7.8, the planet Neptune is very easy to see in binoculars as long as you know exactly where to look for it. It starts October a mere 40 arcminutes from Phi (q Aqr in the direction of Lambda (h) Aqr, and moves the same distance in the same direction as the month progresses. Don’t expect to see a disc; it appears stellar in binoculars, but you can identify it because it moves slightly from night to night. ! SEEN IT

3. TX Piscium

The easternmost star in the southern circlet of Pisces is one of the reddest in the night sky, the slightly variable (mag. +4.8 to mag. +5.2) TX Piscium. TX is a carbon star: it pulsates in size and as it contracts it throws off layers of soot that cause it to dim slightly. You may notice that it seems to get brighter as you look at it, a phenomenon called the Purkinje effect. ! SEEN IT

4. M2

The globular cluster M2 is easy to 10x 50 find: it forms a right-angled triangle with Sadalsuud (Beta (`) Aquarii) and Sadalmelik (Alpha (_) Aquarii) which are due south and east of it respectively. It is obvious in a sparse region of sky, and you can see it as Charles Messier described it: “a nebula without stars”. If you use averted vision in good sky conditions, you might notice that it appears oval and slightly granular. ! SEEN IT

5. NGC 7293

You’ll need a good southern horizon, along with a transparent sky and full dark-adaptation to spot NGC 7293, the Helix Nebula. Look 10° south of Sigma (m) Aquarii and you’ll find Upsilon (p) Aquarii. A little more than 1° to the west, you should see a faint circular patch that is a similar size to M2. ! SEEN IT

6. M30

If you ever attempt a Messier 15x 70 marathon (observing all 110 Messier objects between dusk and dawn), your final morning twilight object will be this little globular cluster, so you’ll need to have practised finding it. Autumn evenings are a good time to start. Identify 41 Capricorni, which lies just over 3.5° east of Zeta (c) Capricorni. Half a degree back towards Zeta you should see the cluster, looking like a slightly defocused star. ! SEEN IT

" Tick the box when you’ve seen each one