The Sky at Night
The Summer Triangle of Vega, Deneb and Altair is moving westwards and its place in the south is being taken by the constellation Pegasus. The distinctive square of four stars which form the body of the flying horse is high in the south with the upper left star of the square being in Andromeda and the remainder of the hind leg being in that constellation rather than in Pegasus. The globular cluster M15 is just in front of the star marking the nose of Pegasus, to the west of the square, always remembering that Pegasus is depicted as flying inverted through the northern sky. The area below Pegasus does not really contain any particularly bright stars with Pisces strung out below and to the east of the Square of Pegasus. If you look below the Square you may see a small ring shaped group of stars which is known as the Circlet of Pisces and below that is Aquarius, also a faint constellation.
Following Pegasus is the small constellation Triangulum, then Perseus, and well to the east the bright yellow star Capella, brightest star of Auriga, while lower in the sky is the contrasting bright orange star, Aldebaran, brightest star of Taurus. For me, Taurus marks the entry of the great winter constellations which will rise towards the south over the next few months.
The Moon has seemed to be absent over late summer and into autumn but this is because, at that time of the year, it is higher in the sky in the early hours when it is close to last quarter while at first quarter it grazes the southern horizon. As we move towards winter it is becoming quite high when close to full at more accessible times for observing. The Moon is best observed with a telescope when the line between dark and light is close to either first or last quarter as the shadows along this line at these times give a feeling of depth to craters. A phase near to full Moon is best for observing the various shades which can be seen in the darker and flatter maria areas.
Following the Perseid meteor shower in August, October brings us the Orionids, the first of what I call the winter meteors. The Orionid meteor shower is active throughout October but reaches its peak on the night of the 21/22 of the month. As the name suggests, the radiant, or point from which the meteors appear to originate, is just above Betelgeuse in the constellation of Orion. Orion rises in the east at about 11pm so it is best to look for meteors well away from this area. You may expect to see up to 20 meteors per hour at maximum but the Moon is 10 days old and doesn’t set until about 4am so its brightness may reduce the numbers seen. It’s interesting to know that the meteoric particles originate from Halley’s Comet and enter Earth’s atmosphere at a high speed so often leave glowing trains which linger for a few seconds.
A reminder for October is that British Summer Time ends on Sunday 25th October and we return to Greenwich Mean Time when clocks go back one hour at 2am.
Sky Notes courtesy of Ken Kennedy of Dundee Astronomical Association.
The Planets
Mercury and Venus
During October, both Mercury and Venus set at much the same time as the Sun and so will not be visible throughout the month.
Mars
Mars rises shortly after midnight and by dawn, around 6am, will be high in the constellation of Cancer in the south-east.
Jupiter
Jupiter rises rather later than Mars at 1.30am and follows Mars through the sky in the constellation of Leo. The planets will be about 15 degrees apart and Jupiter will be brighter than Mars and yellow in colour while Mars will look distinctly orange.
Saturn
Saturn rises at about 6pm in the east and will be almost due south at midnight. Saturn will be well placed for observation in the northern part of the constellation Cetus throughout the evening for the next few months.
The Moon
The Moon will be at last quarter on the 3rd, new on the 10th, at first quarter on the 18th, and full on the 26th October.