Observing Uranus with binoculars, by Mike Feist
Once the binocular-aided skywatcher has located and followed the bright planets of Venus, Mars, Jupiter and Saturn, it is then the time to turn attention to the less obvious planets, Mercury, Uranus, Neptune and Pluto.
Mercury is easily seen at least twice a year, best in spring (at dusk) and in autumn (before dawn). Pluto is so faint that it requires expert knowledge and a substantial telescope to see and identify it. However, Uranus and Neptune are well within the range of visibility to a binocular-user although Neptune is a bit faint and it is no doubt best to start with locating Uranus. It is never fainter than 6th magnitude and therefore, under ideal conditions, can just be seen with the unaided eye, but it is easy with small optics.
The list below gives some of the different instruments that I have used to find this planet. They include an opera glass, and 8 x 32, 8 x 40, 12 x 40, 8 x 63 binoculars. The following monoculars have been used: 6 x 18, 8 x 20, 7 x 21, 8 x 21, 7 x 25, 10 x 25, 8 x 30, 10 x 30, 10 x 46, 10 x 50 and also 16 x 50, 20 x 50 spotting scopes. Telescopes have also been utilised and these include a 1″ refractor, 2″ refractor, 3″ refractor, 80mm short focus refractor and 6″ reflector.
As you will see, anything will do but what will you actually see? In most you will just see a starry point, although a telescope at a reasonably high magnification will show a tiny bluish disc, so you will not be able to study the planet itself as you might with Mars or Jupiter. The pleasure is in locating it and then following it as it moves against the starry background, but how do you find it and where and when is it visible? Uranus is currently (2005) in the constellation of Aquarius and, as it takes 84 years to go round the Sun, it must spend about 7 years in each zodiacal constellation and will therefore remain in this constellation for a few years yet. It is currently visible for the last six months of the year and into the January of the following year. At the beginning of an apparition it can only be seen in the early morning sky but later moves into the evening sky.
To locate Uranus you will first require a map giving its position for the year in question. Such a map is often available in the astronomy magazines or, failing that, in the Handbook of the British Astronomical Association. (This is available yearly, by post, for £7.50 from their London Office – check their website for more details). If you have a good star map, you can plot its position on that, its RA and Dec positions for each year are available from many sources, especially the magazines. You must now make yourself familiar with the stars in the correct area using your binocular and you should easily identify the planet as a faint ’star’. Just referring to the area on a good star map (like SkyAtlas 2000) will reveal the planet as a ’stranger’ not shown on the map. Make a sketch of its position and look again a few nights later and you can prove its identity because it will have moved slightly (unless you are unlucky to chose the time when it is changing direction and at one of its ’stationary points’). Once located you can easily pick in up on any clear night from summer to winter.
Now is the time to search out Neptune, but that is another story.