Planets on display

While the Red Planet slowly fades after coming to opposition, challenge yourself to look upon the green-tinged, distant Uranus

Give yourself more of a challenge this month and spot green-hued ice giant Uranus

Many amateur astronomers and sky-watchers have never even bothered to look for Uranus because it has a reputation for being too faint, too boring and too bland to look for when there are so many bright, exciting and colourful things to look at.

Indeed, it is so unremarkable visually that it was seen in the night sky, recorded and mistaken for a star by several notable observers before it was eventually recognised as a planet by William Herschel in 1781.

After its discovery Uranus was observed regularly by professional astronomers, and their calculations showed it lies almost 20-times further from the Sun than the Earth and orbits the Sun once every 84 years. But no matter how big a telescope they used they only ever saw Uranus as a small, featureless, blue-green disc. It took the Voyager 2 probe, speeding past Uranus in 1986, just days before the Challenger space shuttle tragedy, to turn that bland disc into a real world.

We now know that Uranus is an ice giant world, four-times wider than Earth, with a system of nine dark rings and a family of 27 moons, some of them as fascinating as the more famous satellites of Jupiter and Saturn. Although the planet’s atmosphere appears blank and featureless as seen from Earth, just as it did to the Voyager probe’s cameras, we now know that it does have structures, cloud bands and storms shaped by the planet’s ferocious, 900 kilometres (559 miles) per hour winds.

It’s no real surprise that Uranus hid in the sky undiscovered for so long: shining at just beneath sixth magnitude it is, technically, a naked-eye object, but to see it without optical assistance of some kind you would have to have very good eyesight, be standing beneath a pitch-black sky with no light pollution or moonlight to spoil the view and know exactly which one of the many, many faint stars ‘up there’ it is.

This month Uranus is an evening object, lurking among the unremarkable stars of the unremarkable constellation of Aries. At the start of our observing period it rises around 10:30pm and is visible through the night until the sky begins to brighten with the approach of dawn. By the middle of September Uranus is rising before 9pm, so will be visible earlier and for longer.

Although your chances of seeing it with your naked eye are slim for the aforementioned reasons, binoculars will make it stand out from the crowd of stars around it by enhancing its green-blue colour.