Astronomy is very weather dependant. How many of us set our alarms to wake us for the lunar eclipse only to be faced with a bank of cloud? Me for one. But we can look forward to the next on the evening of January 9 2001.

February brings a chance to try and see the elusive planet Mercury. In the week surrounding the 15th Mercury will be setting after the Sun. At best on the 15th at 18:00 it will be just 6 degrees above the horizon. At the same time Mars will be at an altitude of 19 degrees and to the left of Mercury. The time to start looking is just after sunset which on the 15th is about 17:46. It can be helpful to use binoculars to locate Mercury before using your unaided eye or you could do what I do and take along a sharp-eyed friend! No matter if you don't see Mercury this time, as there will be plenty of chances later in the year.

One feature of Shetland weather that affects astronomy, especially with a telescope, is the wind. If a telescope is magnifying 200 times that slight breeze moves the image in the telescope all over the place. So unless you have an observatory astronomy with the unaided eye or binoculars is best in our climate.

There are as many constellations in the sky as there are keys on a piano - 88. We cannot see all of them from Shetland but some of the main winter ones such as Orion the hunter and Taurus the bull are well placed at the moment.

Study the chart before you go out to look at the stars and try to face South. Orion should be visible ahead of you. Over to the right will be Saturn and Jupiter.

If you have binoculars look at Jupiter and you will see some points of light close to the planet. These are some of Jupiter's moons.

There is much mythology in the night sky.

The great planet Jupiter, the Roman "Heavenly Father", is identified with the Greek god Zeus.

Zeus was not faithful to his wife Hera, and enjoyed dabbling with mortals. The four moons of Jupiter - Io, Europa, Ganymede and Callisto - are named after his most famous seductions:-

Io was a priestess of Hera whom Zeus was besotted with. He visited her disguised as silver mist but was foiled before he could achieve his objective. Io was turned into a heifer, and given to Hera who placed Argus Panoptes, the man with the many eyes, as her guard. Hermes killed Argus Panoptes (whose eyes were placed in the peacocks' tail), Io escaped and had many adventures. Zeus eventually caught up with her beside the Nile, where he took the form of a bull and found satisfaction. Io was returned to human form, bore a child, married and moved to Egypt - where she was connected with Egyptian mythology as Isis, wife of Osiris.

Falling in love with Europa, Zeus arranged for Hermes to drive a herd of cows along the seashore where she was playing. He then turned himself into a great white bull and wandered gently amongst the herd, munching a crocus. Europa was drawn to him, stroked him and eventually climbed onto his back, where upon the bull dashed into the sea and swam to Crete. Europa stayed in Crete as Zeus's mistress and bore him three sons, one of which was Minos. Europa gave her name to the continent of Europe and can be seen as Jupiter's second moon.

Ganymede was a beautiful youth who was abducted by an eagle and carried to Mount Olympus to become Zeus's cupbearer, etc, and was placed amongst the stars as Aquarius. The eagle was immortalised as the constellation Aquila.

Callisto was turned into a bear after she was seduced by Zeus in the form of Artemis. She became the constellation Ursa Major, the big bear - part of which is known as the plough.

Taurus, the Bull, represents the form, which Zeus often took in his seduction attempts.