Moon lights up lots of interest in the night skies

THE MONTH starts with a waning crescent Moon that becomes new, or is born again, on July 8 at 8.09am and as the Moon is still close to the Sun at sunset, the first crescent will not be visible. It will become visible, weather permitting, the following evening, so Ramadaan starts after sunset on July 9.

Venus now shines brightly, low in the western sky after sunset as the Evening Star: a misnomer as it is not a star but a planet, and it can also appear in the morning sky. This month sees a lot more interesting activity in the night skies, and, weather permitting, it is worth keeping a regular eye on the night sky, with the Moon playing a key role in helping you each night. From July 10 to 25, it passes by several stars, planets and constellations.

Starting on July 10, a thin waxing crescent is just to the left Venus and the following evening also slightly to the left of Regulus, the brightest star in the constellation of Leo. By July 15, a near quarter Moon is just to the left of the bright star Spica and the following evening, it will be to the left of the ringed giant planet Saturn. On July 18, a waxing gibbous Moon is just to the left of the pincers of Scorpio and on the following night, just below the red supergiant star Antares, at the heart of the scorpion. Then from July 19 to 25, Venus is approaching Regulus in Leo, and on July 22, they are very close indeed, after which Venus rises higher in the sky each night, leaving Regulus below.

What I find interesting is that the Moon moves relatively quickly across the sky; although the planets move as well, they do so much slower and it is often hard to detect this movement. However, the Moon’s position can be used to identify a star or planet that it is close to. But the movement of planets relative to the background stars only becomes noticeable when it is close to a star, as Venus is to Regulus on July 22. Ancient astronomers were aware of this movement and gave them the name “planetes”, Greek for “wanderers”, since they wandered among the background stars – hence the modern name “planet”.

Scorpius, the Scorpion, is almost overhead with the bright star Antares at its centre. Antares is a supergiant star about a billion kilometres in diameter, about 750 times bigger than our Sun. Its surface has cooled to about 3 000ºC, giving it its red appearance, but it is more than 9 000 times more luminous than our Sun and is 520 light years away. To the Chinese, it was the “Heart of the Dragon”, the Romans called it “Cor Scorpionis” and the French call it “Le Coeur de Scorpion”, both of which mean “Heart of the Scorpion”.

Looking south, the Southern Cross and the Pointers are high up in the south-west with Canopus and Acherner just to the west and east of south respectively and very low. Looking north, the bright star Vega is visible low in the north-east, with Arcturus low in the north-west in the constellation of Bootes.

The morning sky is far more interesting this month with “isiLimela”, the digging stars in Xhosa (the Pleiades or Seven Sisters) making a welcome return, reminding us not only to start preparing the soil for planting, but also that there are seasonal changes. The small open cluster, the Hyades with the reddish star Aldebaran, the eye of Taurus the Bull, is also visible, to the right of isiLimela. Further east, Orion returns to the morning sky.

There is the usual Open Night on July 13 at 8pm and it includes a tour of the site (weather permitting), stargazing and a talk, “A Pictorial Tour of the Sutherland Observatory”, by Willie Koorts.