ASTRONOMY 101: BINOCULARS

Despite having a couple of sizable telescopes my favourite piece of astronomical equipment is still a humble pair of binoculars that I bought at a car boot sale for under 5GBP!  They are portable, light and easy to use on cold, damp but clear nights!

My 10 x 50 Super Zenith binoculars bought for 5GBP second hand.
 With a Field of View (FOV) of 5.5 degrees they make for fantastic
views of open star clusters and some of the brighter deep sky
objects such as M31 The Andromeda Galaxy and M42, the Great
Nebula in Orion.

And they are all you need to get the ‘wow’ factor from a selection of objects that are annoyingly just beneath naked eye visibility in this month’s night sky. From a reasonably dark location in the Northern Hemisphere binoculars will bring the Andromeda Galaxy into view, along with the star forming nebula in the hunter’s sword in the constellation of Orion after dusk.

The moons of Jupiter will magically appear, as will a multitude of star clusters.  Paradoxically, some objects actually appear more spectacular through binoculars than through a telescope, due to their large field of view. The Seven Sisters or Pleiades is an example of this, and binoculars show that there are many more stars in the cluster than just seven!  The Moon is stunning at any time with its craters such as the magnificent Tycho and Copernicus.  Binoculars will give you great views of the lunar Mare or Seas such as the Sea of Tranquility where men first landed in July 1969!

For illustration purposes only, this is a mock-up using Stellarium planetarium software of what Orion's Sword and M42, the Orion Nebula look like through 10x50 binoculars.

The most suitable binoculars for astronomy are those with the specification of ‘ten by fifty’.  The ‘ten’ refers to the magnification while the ‘fifty’ refers to the size of the aperture or the lens that lets the light in. Binoculars that are larger are too heavy leading to shaking hands, while those under seven by forty simply don’t allow enough light in for relatively dim night sky objects.

For a reasonable pair of new binoculars expect to pay the equivalent of around 30 to 50GBP, but the real bargains are to be had at boot sales and on eBay where a good second hand pair can go for as little as a couple of pounds. Ensure they include a case and check the lenses for scratches.

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