Sky Diary

The Sky at Night

The flying horse, Pegasus, dominates the high southern sky during October. The great square forming the horse's body really stands out despite the stars of the square not being particularly bright. If you are still not sure, look towards the south and you will see brilliant Jupiter sitting directly below the lower left hand star, Algenib. The upper left hand star of the square, Alpheratz, is not in Pegasus but is in Andromeda. With a pair of binoculars, find Alpheratz and move left, or eastwards counting two stars. Now slowly move directly upwards by about 5 degrees and you will see a fuzzy oval, not very bright but quite easy to see in binoculars. This is the Great Andromeda Galaxy, our nearest large galactic neighbour. In astronomy, 'near' is a word which is relative but compared to many distant objects out there, 2.5 million light years is quite close to our Milky Way Galaxy.

We generally think of a New Moon as being a thin crescent but in astronomical terms, the New Moon is the point when the Moon passes directly between the Earth and Sun. Because of the inclination of the angle of the Moon's orbit to that of the Earth, the Moon usually passes above or below the Sun but occasionally it will pass in front of the Sun. When this happens we have a solar eclipse which can be seen in some areas on Earth. On the 25th October there is a partial solar eclipse which will be seen from the UK. In mid-Scotland the eclipse will begin at 10.03am, mid eclipse at 10.55am and it will end at 11.50am. The Sun will be towards the south south-east at an elevation of about 18 degrees and at maximum eclipse about 20% of the Sun will be covered by the Moon so it will look as if a bite has been taken out of the Sun. Remember though, that whether you use binoculars, a telescope or simply look without optical aid, make sure you look through a proper solar filter which will protect your eyes. Alternatively try to project the Sun on to a white card through your instrument or if you don't have anything optical, pierce a small hole in a piece of cardboard and project the Sun shining through it on to a white card.

In October we have the Orionid meteor shower which peaks on the 22nd, so have a look for a few days either side of that date. This shower gives about 20 meteors per hour at maximum. The meteors are fast and often leave persistent trains which glow for a few seconds after the bright streak of light. This is a very favourable year with a 27 day old Moon which will not interfere with bright light throughout the night. As always, find the darkest spot you can and look towards the darkest part of the sky which you can see.

The Planets

Mercury

Mercury

Mercury will be best seen before sunrise for a few days around 8th October low towards the east. It should be possible to see Mercury until about mid-month.

Venus

Venus

Venus will be too close to the Sun to be visible throughout October.

Mars

Mars

Mars rises at 8.30pm and will be visible throughout the night reaching its highest point due south at 5am.

Jupiter

Jupiter

Jupiter will be towards the south at 11pm and sits at an improved elevation compared to the past few years. It will be bright among a rather faint star background and will be interesting to watch with binoculars or telescope.

Saturn

Saturn

At about the same time, Saturn will be approaching the south-west but remains at a low elevation of about 10º.

The Moon

The Moon

The Moon will be at first quarter on the 3rd, full on the 9th, at last quarter on the 17th and new on the 25th October.

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