May: Winter is coming – it’s written in the stars

The Carina Nebula, NGC 3372, is an enormous cloud of gas and dust that’s home to several massive and bright stars, including at least a dozen that are 50 to 100 times the mass of our sun. With the active, unstable supergiant star Eta Carinae at its heart, the nebula is about 7500 light-years from Earth and was the target for one of the first images by the James Webb Space Telescope. Photo: MPAS member Chris Kostokanellis.

The Milky Way rises high in the south this month, with Sagittarius and Scorpius sitting in the east – a clue that winter is on its way in the southern hemisphere. Sitting high in the southern sky during May is the prominent constellation Crux, the Southern Cross. If you have a small telescope, be sure to point it at Crux’s brightest star Acrux, which is actually a double star made of two blue-white stars.

The large constellation Centaurus, the Centaur, sits within the stunning star fields of the Milky Way. It is home to arguably the finest globular cluster in the whole night sky – the magnificent Omega Centauri, or NGC 5139. At 10 times the size of the next-largest cluster, you can see it easily as a hazy star with the naked eye, whereas a telescope reveals many of its millions of stars in a tight ball. The constellation’s two brightest stars are Alpha and Beta Centauri, known more familiarly to astronomers as Rigil Kentaurus and Hader. Together, Alpha and Beta Centauri form the Southern Pointers, or The Pointers, as they point towards the constellation of Crux.

The annual Eta Aquariid meteor shower, which is caused by leftover dust from Halley’s Comet entering our atmosphere and vaporising, peaks about May 6-7. You can expect to see roughly 30 meteors an hour if you are very lucky. The meteors appear to be coming from a point near the star Eta Aquarii in Aquarius, and tend to be quite fast-moving.

This month’s conjunctions, which are when two astronomical objects appear close to each other in the sky, include the moon and Saturn on May 13, the moon and Venus on May 23, and the moon and Mars on May 25. Then on May 27, Mercury is at its highest altitude in the morning sky, followed by its greatest elongation west on May 29, which means it is at its farthest distance from the sun.

By Nerida Langcake
This article appeared in the May 2023 issue of the Mornington Peninsula Magazine.