The night sky in May. Illustration supplied by the Society for Popular Astronomy

There is a new moon on the 3rd May, first quarter on the 10th, a full moon on the 17th and last quarter occurs on the 24th. For the amateur astronomer the moon provides more detail than any other heavenly body.

The best time for observing is either side of the first or last quarter as it is too bright around the time of full moon.

The moon always keeps the same face turned towards us as its orbital period is exactly the same as its rotation period, 27.3 days.

The most striking of all the features on the surface are the dark areas known as ‘maria’, a Latin word meaning seas, first used in the seventeenth century.

• Shropshire Astronomical Society website

The constellations in the southern hemisphere. Illustration supplied by the Society for Popular Astronomy

Early astronomers believed maria to be seas of water but we now know they were once seas of volcanic lava from eruptions that took place about three billion years ago following massive impacts. Over time the lava consolidated to form dark areas of basalt rock.

On the 11th, the moon is near the bright star Regulus in the constellation of Leo, on the 13th it passes beneath the planet Saturn. The moon is near the star Spica in Virgo on the 14th, then on the 17th and 18th , low in the south, the moon is in the company of the star Antares in the constellation of Scorpius. Just before dawn on the 29th the crescent moon can be seen directly above the planet Jupiter, then close to the planet Venus on the morning of the 31st May.

The most prominent star in the May night sky is the orange-coloured Arcturus, overhead but slightly to the south. Arcturus, from the Greek for ‘bearkeeper’, is in Bootes (the Herdsman), a constellation mentioned in Homer’s Odyssey. Arcturus was believed to drive the Great Bear, Ursa Major, around the northern sky as the Earth rotates. To locate this star, follow the tail of the Plough that arcs down to Arcturus. Arcturus is a red giant about 30 times bigger than our Sun, its rise to glory in the May night sky is a promise that summer is on the way. Above and to the left of Arcurus is a good telescope object, the beautiful double star Izar, one star is blue the other yellow.

The ring world of Saturn is the only planet on view all night long, it is found looking south lying in the ’Y’-shaped constellation of Virgo. Using a telescope, Neptune can be found in the constellation of Aquarius, the planet rises in the south-east about 2.30 am. The planet Venus is difficult to see as it is low in the south-east an hour before sunrise. Towards the end of the month, equally difficult to spot and to the right of Venus, the giant planet Jupiter makes an appearance about an hour before the Sun.

The maximum of the Eta Aquarid meteor shower occurs on the 4/5th May as the Earth passes through the debris field left behind by Halley’s comet. The shower occurs around the time of the New Moon so it is a good year for observing these ‘shooting stars’.

Ron Iremonger