Month’s planets

You can still catch Uranus, while Venus dazzles for early risers

This is a great month to track down Uranus in the night sky. Many people consider Uranus to be the ‘Forgotten Planet’ of the night sky, because although it is bright enough to be seen with just the naked eye, if you know exactly where to look, relatively few amateur astronomers have ever actually seen it, or even bothered to look for it. Why? Perhaps because it looks like a very faint star to the naked eye, even from an observing site without any light pollution. Or maybe it’s because even through a telescope, the seventh planet out from the Sun looks like nothing more than a tiny, featureless, blue-green disc. Whatever the reason, it is definitely a neglected object. This is a shame because it is a fascinating world in its own right.

When it was discovered in 1781 by William Herschel, it was the first planet to be discovered since ancient times. The discovery of a world 19-times farther from the Sun than Earth – that’s 1.8 billion miles or 2.9 billion kilometres – caused a sensation, because it meant the size of the Solar System increased enormously overnight. Uranus is so far away that when you look at it through a telescope, the light passing through the eyepiece and into your eye set off two-and-a-half-hours earlier.

Today, after 236 years of studying it, we know Uranus is an 'ice giant' world with a system of dark, faint rings and a family of at least 27 moons. We also know that there is a lot more to know about it. Only one probe has studied Uranus – Voyager 2 – and when it raced past in 1986 without stopping it allowed planetary scientists to barely scratch the surface of what it has to offer. Now that the Cassini mission to Saturn has ended, there is a lot of interest in the planetary science community in a return to Uranus, with a Cassini-type orbiter. A modern probe carrying 21st century cameras and instruments would surely revolutionise our understanding of that distant, turquoise planet in the same way Cassini let us see Saturn through new eyes.

This month Uranus is visible in the evening sky right after sunset. You will see it as a star with your naked eye but only if you are under a truly dark and Moon-free sky, and know exactly where to look. At magnitude 5.7 it is one of the faintest things you can see in the sky, and looks exactly the same as several thousand genuine stars which are the same brightness. Your best chance of seeing it is through a pair of binoculars, scanning the area of the sky Uranus is in, and trying to pick it out from the background stars using charts either in books or generated by your favourite phone or tablet astronomy planetarium app. If you are under a dark sky your eye will pick it out as a greenish star.

Constellation: Scorpius Magnitude: -0.3 AM/PM: PM

At the start of November, Mercury – the closest world to the Sun – is too close to our nearest star to be visible, but as the days pass it slowly moves further and further away from the

Sun. Sweeping the sky with binoculars might help, but only after the Sun has safely set. Best chance to see it comes on 21 November when it will be to the lower right of a pairing of Saturn and a very slender crescent Moon.