The Sky at Night
February sees the glorious winter constellations slowly drift westwards in the night sky and begin to be replaced by constellations associated with spring. Despite cold and possibly snowy conditions this month there is a hint of rising temperatures and lengthening days to come. The twins, Gemini, cling to the southern sky and are due south at about 10pm during the month. One of the original 48 classic constellations of the second century AD it is identified by its two brightest, but quite different, stars Castor and Pollux. These stars form the heads of the twins, Castor higher in the sky with Pollux below it. Even a casual glance will show Castor to be a blue-white colour while Pollux is something of an orange shade. Although appearing as a single star to the unaided eye, Castor consists of a system of six stars, three of which can be separated in a telescope while the other three are too close for visual separation. Pollux is a much cooler star than Castor and has evolved into a red giant which is in the order of 700 million years old. Pollux is known to have at least one planet in orbit around it. It is more than twice the mass of Jupiter and takes 590 days to complete one orbit. Castor is 51 light years distant from Earth and Pollux is a bit closer at 34 light years, really quite close it astronomical distances.
Following Gemini is the rather inconspicuous constellation of Cancer, the Crab. In urban conditions it is likely that only its brightest star, Altarf, will be seen so the inverted Y shape of the constellation will not be obvious. However, binoculars out again and, and if you move slowly on a line extended between Castor and Pollux, you should come across a bright group of stars known as the Beehive Cluster. This is one of the first distant objects studied by Galileo with his telescope in 1609. The origin of the name is uncertain – but do you think it looks like a swarm of bees round a hive? Following Cancer in the sky is Leo, a spring constellation, and a subject for another month.
It will be possible to see Mercury low in the west after sunset for the last week or so of February. Mercury will set at about 6.30pm, an hour after the Sun,
Jupiter is just to the west of Venus in early February rising at about 3.30am.
Venus will be low but bright in the south south-east at about 7am, rising about 1½ hours before the Sun. It will gradually become lower in the sky throughout February.
Saturn rises at 5.30am, about an hour before the Sun. It will be close to Venus on the 18th February but will be low and quite difficult to spot.
Mars is well placed in the south-west by 7pm, setting at 11.30pm. Mars moves from Pisces into Aries on the 12th of the month,
The Moon is new on the 4th, at first quarter on the 12th, full on the 19th and at last quarter on the 26th of February.
During February Mills Observatory will be open Monday to Friday from 5pm until 10pm and on Saturdays from 12.30pm – 4pm. There will be planetarium shows on Friday 1st and 15th February at 6pm, 7pm and 8pm. There is a charge of £1 for adults and 50p for children and booking is essential at 01382 435967. The next talk in the Zenith Points series will be on Saturday 16th February at 2pm when Bill Samson of Dundee Astronomical Society will speak about ‘Finding Your Way Around the Night Sky’. These talks are intended for older children and adults. There is no charge for these talks but please book at the above number.