Star gazing: The skies in March

'O Moon, when I gaze on your beautiful face, careering along through the boundaries of space... the thought has often come into my mind... if ever I shall see thy glorious behind'.

The English poet Edmund Gosse claimed his housekeeper penned these lines. Although not the most brilliant literary offering, the poetess was an accurate observer. She'd noticed that the Moon always presents the same visage towards the Earth. Gravity is the reason. The Earth is so massive, and the Moon so close, that our satellite's spin has been "locked", so we see an unchanging lunar panorama.

The Moon's visage is the legacy of billions of years of bombardment. Craters and huge features gouged out by asteroids make up the "face" of the "Man in the Moon".

Galileo is widely credited with making the first map of the Moon through his tiny "optick-tube" – a home-made telescope – in the early 17th century. But the honour actually goes to an English Oxford scholar, Thomas Harriot, who turned his telescope to the skies months before the feisty Italian. Harriot's patron, Sir William Lower, observed that the Moon was "as a tart that my cooke has made me last weeke; here a vaine of bright stuffe, and there of darke, and so confusidlie all over".

This year, we celebrate the achievements of Harriot and Galileo with the International Year of Astronomy (IYA) – it's 400 years since they pointed their telescopes at the skies.

The Moon, even through a small telescope, is sensational. As part of the IYA celebrations, 28 March to 5 April is Moonwatch Week. All over the country, astronomical societies will have star parties, telescopes and experts on hand. For an event near you, visit www.astronomy2009. co.uk/index.php/gem.

During Moonwatch Week, there's a bonus: beautiful Saturn. It's now at its closest to Earth, just under the tail of Leo the Lion. The ringworld is circled by 60 moons, and its largest, Titan, is covered in lakes of liquid methane – a possible precursor to future life. Saturn is breathtaking, like a perfectly crafted model floating in space.

What's Up

Glorious Venus has been a familiar sight blazing high in the west in the evenings. But, late this month, the Evening Star will disappear – to be reborn as the Morning Star. For a few days, you may be able to catch the brilliant planet in both the evening and the morning sky. Immediately after sunset, scan the sky just to the right of where the Sun has set, to pick out Venus in the twilight. Next morning, scan the horizon to the east at about 5.30am to see Venus as Morning Star. Stop observing the moment the Sun rises, so you don't scan across its blinding surface.

The stars of winter are now slipping down towards the west, their place being taken by the large but dim constellations of spring. As well as Leo, these include Cancer, Virgo and the long straggly star-pattern that makes up Hydra.

Heather Couper and Nigel Henbest

Diary

4 7.46am Moon at First Quarter

8 Saturn at opposition

11 2.38am Full Moon

18 5.47pm Moon at Last Quarter

20 11.43am Spring Equinox

26 4.06pm New Moon

28 Moonwatch Week starts

29 1.00am BST starts