Uranus at Opposition 2013
The gas giant planet Uranus, the seventh planet in our solar system, reaches opposition today at 1558 BST (1458 UT), meaning that this is the best time of the year to find this elusive planet.
Opposition is the name astronomers give to the point at which a planet is directly opposite the Sun in the sky. This means that the planet rises as the sun sets, gets to its highest in the sky at midnight, and sets again when the sun rises, meaning that it’s in the sky all night long.
The exact instant of Uranus’ opposition this year occurs on 3 October at 1458 UT, but Uranus moves so slowly against the background stars that there will be ideal observing conditions all month long.
Uranus was the first planet to be discovered after the invention of the telescope. It was first seen in 1781 by Sir William Herschel. The reason it hadn’t been seen before was that it is not a naked eye planet… But actually it is. At opposition tonight Uranus shines at magnitude 5.8, which is right at the edge of what’s possible to see with the naked eye. You’ll need really dark skies to see it, and perfect eyesight too, but even if you can spot it without a telescope it will only look like an incredibly dim star. Through a telescope you might make out a tiny blue-green disk, only 10% the diameter of the much nearer and much larger Jupiter.
To find Uranus look for the constellation of Pisces high in the south at midnight UT, or 1am BST. Uranus rise to between 30° and 40° above the horizon, depending on your viewing location in the UK. Here’s a handy finder chart (courtesy of Stellarium):