Binocular Astronomy

Want to learn more about what you can see with only a pair of binoculars? AOP’s own Prof. Simon Jeffery explains how to get the most out of a pair of binoculars, and also issues you a challenge!

A popular caricature of an astronomer shows an elderly gentleman with a long greying beard, stooped over the eyepiece of a long telescope, its upper end poking through the aperture of a lonely tower atop a rocky mountain ridge. Whilst absolutely accurate, it should not deter the rest of us from using whatever aids we can lay our hands on to get our own view of the heavens. I am often asked what sort of telescope should be bought for a daughter, husband, mother who is really interested in astronomy. In reply, I’ll often ask – what about a pair of binoculars?  

When viewing the night sky, assuming it is really dark and beautifully clear, the vital things are aperture – to collect as much light as possible,  and stability – to keep the faint pin-pricks of light from dancing  around. A telescope can give both, but takes time to set up and can be tricky to point, especially on a cold night. For a spectacular view of the moon, or the planets, and even some of the brighter nebulae, a good pair of binoculars brings great rewards, and can be used in hundreds of other ways as well. 

I learnt this lesson a few years ago. One crystal clear October night in Connemara, I was looking at Jupiter from the comparative warmth of a sitting room window. I wondered whether I could get a better view with my binoculars. Out of curiosity, I tried to take a picture. Holding the glasses against the window, and my phone to an eyepiece, I took a couple of shots. There was a bright spot – Jupiter!  Job done, or so I thought. 

My phone auto syncs to google photos, … so  I could look at the pictures online. Zooming in I was astonished to see faint points of light close to the bright planet; four dots all in a line! I realised I was seeing what Galileo saw when he first pointed a telescope at Jupiter. He went on to watch those dots move from hour to hour and day to day, as he realised they were moons that were moving round their bright companion. The result was a revolution in astronomy and massive controversy with the church.

I put the photo on my Flickr account, where it was discovered ten years later by NASA who decided to use it in a video about astronomy with binoculars. So take a look to see what else you might look at. 

Jupiter Challenge 2020 

This is something nearly any one can do, and Jupiter will soon (July 14) be at its brightest and moving into the evening sky. Your first challenge is to take a photo of Jupiter through binoculars, or some other device, with your phone or tablet. Remember to hold them very still. Then zoom in and see if you can identify the moons.

The next challenge is a bit harder. Try to take a series of photos over several hours and nights, and see if you can spot the  moons changing position. How long does it take each moon to return to near the position in your first picture? Hint: the time will be different for each moon, and you might need to keep looking for a few weeks. 

Finally, in December, Saturn and Jupiter will be closer together on the sky than at any time for 300 years. If you’ve been practising with the moons project .. try catching a picture of Jupiter, its moons, Saturn and its rings, all in the same picture. 

Armagh Observatory and Planetarium would love to see your pictures of Jupiter’s moons. You can crop them if you want, but make sure to send them as jpeg files, together with a description of the phone and binoculars you used, to simon.jeffery@armagh.ac.uk.