Wednesday, 7 March 2012

Planet Mercury At Greatest Eastern Elongation

Look due south in the evening sky this month and you can't fail to see the spectacular sight of the planets Venus and Jupiter in close conjunction. Look to the east later in the night and you can also see a spectacular view of Mars, shining a bright copper red in the constellation of Leo. But they're just the obvious ones. With a little bit of effort, you can also get a rare glimpse of Mercury: the most elusive planet you can see with the naked eye.

Mercury is the closest planet to the sun and is usually lost to view in the solar glare; however, there are a few times each year when the planet is at the farthest point in its orbit from the sun (as viewed from here on Earth) and can briefly be seen, either just before sunrise, or just after sunset. At the moment, Mercury is at its greatest eastern elongation, which means that you have a window of about an hour to spot it in the early evening sky - assuming the weather is favourable of course.

So, find yourself a clear view of the southwestern horizon and start looking after the sunset from about 6.45 pm onwards, when the sky should be just about dark enough. Mercury will be low down, close to where the sun has just set and well below Venus and Jupiter. It will be the only star-like object visible in that area of sky.

I went looking for Mercury myself this evening and finally spotted it just after 7.00 pm, at about 10 degrees above the horizon. Once you've clocked Mercury, it is quite distinctive and looks like a pale, solitary star with a slightly pinkish hue. You will have to look hard to find it, but it isn't something you can see every day, so why not give it a shot? Mercury is visible until March 10th when it will be too close to the sun once again. And even if you can't make it out, you can always enjoy watching the beautiful stars of Orion, Canis Major and Taurus as they magically appear in the darkening skies.