05-01-2008 January night sky (Article 119)

[Simon Kenny]

January night sky (Article 119)

With early darkness you can get in a lot of observing at a reasonable hour during January. So, what’s on view at say 10 pm throughout this month?

The Moon rises at 2:16 am on the 2nd, but on 13th looking West it will be rising at 10 pm when it will be 5.4 days old with 29% of its disc illuminated by the Sun. It will gradually show more of its disc during January and on 17th will be quite close to an easy to spot star cluster called The Pleiades (or the seven sisters) when it will be 9.7 days old, 47º above horizon with 73% of its disc illuminated. Try looking South at 8 pm on 19th and the Moon will be very close to the planet Mars that will appear as a distinctive orange colour. On 24th looking East the Moon will be very close to the planet Saturn (which will look like a bright star in the constellation of Leo). It will be only 25º above the horizon and at 17.2 days old will have 93% of its disc illuminated. The last you will see of the Moon at 10 pm will be on the 26th when it will be just on the Eastern horizon. If you are new to casual observing this will be very easy and you do not need a telescope or binoculars, just your eyes.

Mercury is very close to the Sun and sets very early in the evening in the Southwest throughout January (Warning -- Never look at the Sun through binoculars or a telescope, instant and irreversible blindness will result). Venus will make morning appearances during January and before Sunrise on the 31st it will be very close to the planet Jupiter at 7am in the Southeast.

At 10 pm looking South the planet Mars lies between the constellations of Gemini and Taurus. It is 62º above the horizon and shines at a very bright magnitude of -1.49 (on the magnitude scale only a relatively few objects are bright enough to have a negative rating). The image below will help you identify its location. Mars lies some 91 million kms. from Earth and even with a decent telescope it is quite small and hard to see much detail. Even with the naked eye you cannot mistake its orangey/red colour -- not surprisingly it is known as ‘The Red Planet’.

To find the planet Saturn at 10 pm look East about 11º above the horizon just under the constellation of Leo. It shines at magnitude 0.58 and looks like a bright star, but it will not be anything as bright as Mars. Each night it will gradually reach higher in the sky and by the 31st it will be 30º high. It is worth recalling that Mars has a diameter of 6,794 km. and is presently 91 million kms. from Earth while Saturn plus its ring system has a diameter of 274,000 kms. and currently lies 1,300 million kms. from Earth.

The rest of the planets will not be visible at 10 pm during January.