September Night Sky

September is the month when I make my annual attempt to have a good look at Neptune. It is not an easy target. It comes to opposition on the 1st of the month, at magnitude 7.8 it is a reasonable binocular object if you know where to look, but that is part of the problem. It is right in the middle of Aquarius, one of the fainter constellations, and will be at its highest at around 11pm mid month at about 30 degrees above the horizon, due south. The general direction is south following the line of the 2 right hand stars of the Square of Pegasus, about twice as far as that side of the square; then a little west. That takes you into Aquarius. The best bet is normally to use the finderscope to get to the right part of the sky, and then to check the appearance of the objects in the main scope, initially at low power, then higher magnification to make sure. The main satisfaction is to see the planet at all – especially now that it is officially recognised as the most distant solar system planet.

If you are really ambitious you could try to spot Triton, Neptune’s largest moon, which in size is comparable to our own. At magnitude 13.5, and 2-3 minutes of arc away from Neptune, it should be an interesting challenge!

Neptune in September 2015