Monthly sky maps from the 2021 Australasian Sky Guide published by MAAS Media.
What’s in the sky this May?
Constellations are groups of stars that form a picture. These pictures were given names and for millennia have been used as a tool for navigation and to share significant cultural stories. Astronomers use these constellations to delineate portions of the sky and as a way for locating astronomical objects. In May the following constellations dominate the autumn sky:
- Orion – the hunter is on his side, low in the western sky after sunset. Orion is easy to find, with the best-known feature of this constellation the ‘Saucepan’ asterism. This is a familiar group of stars for those of us in the southern hemisphere and is Orion’s belt and sword.
- Canis Major – the great dog is high in the western sky in the early evening. The brightest star in the constellation, Sirius, is also the brightest in the night sky. It is bright as it is close to us, only 8.7 light years away or about 82 million million kilometres from us.
- Carina – is high in the southern sky and represents the keel of a ship. Carina was originally part of the constellation Argo Navis (Argo was the ship of Jason and the Argonauts) and the nearby constellations of Vela (the sails) and Puppis (the stern) formed the rest of the ship. In 1756, Nicolas Louis de Lacaille published his catalogue of the southern stars showing Argo Navis divided into the three constellations we see today. Canopus, the second brightest star in the sky, can be found in Carina and is a white supergiant star about 313 light years away.
- Vela – is high in the southern sky and represents the sails of the former constellation Argo Navis. During the division of Argo Navis, the stars in Vela were not given new Greek letter designations so Vela has no alpha or beta stars, instead gamma Velorum is the brightest star in this constellation.
- Scorpius – rising in the eastern sky after sunset is the Scorpion. Scorpius is one of the easiest constellations to pick out as it is one of the few that does look like what it’s supposed to represent. Look for the Scorpion’s heart, the red supergiant star Antares and follow the body along to the hooked tail and sting. The scorpion plays a role in many myths, however it is best known in Greek mythology for its pursuit of Orion through the night sky.
- Southern Cross (Crux) and the Pointer Stars – high in the south-eastern sky you will see the Pointers – Alpha and Beta Centauri. The Pointers are to the east and slightly south of the constellation Crux, better known to us as the Southern Cross. The Pointers are one way to check you have the right cross as there are many star patterns in the southern sky that look like crosses.
- Centaurus – surrounding the Southern Cross on three sides is Centaurus, the Centaur, said to represent the scholarly Chiron, tutor of many of the Greek gods and heroes. The Pointer Stars make up the front legs of the centaur, with the brightest of the two (the Pointer most distant from the Southern Cross), Alpha Centauri, the brightest star in the constellation.
Mars is visible in the evening sky and is joined by Mercury and Venus in the evening twilight. This month, Jupiter and Saturn are in the early morning sky.
- Mars – is in the north-western evening sky in the constellation of Gemini after sunset. The waxing crescent Moon is below and to the right (north) of Mars on May 16.
- Mercury – is low in the north-western twilight sky after sunset and will be visible from the middle of the second week of the month. Mercury is in the constellation Taurus and moving closer to the horizon. By month’s end will be lost in the twilight.
- Venus – is low in the west in the early evening twilight sky. On May 13, a very thin waxing crescent Moon maybe visible above and to the right (north) of Venus.
- Saturn – is high in the north-eastern morning sky in the constellation Capricornus. The last quarter Moon will be above and to the right (east) of the ringed planet on May 4.
- Jupiter – the largest planet in our Solar System. It is high in the north-eastern morning sky in the constellation Aquarius. On May 5, the waning crescent Moon is above and to the right (east) of Jupiter.
For the monthly movements of the Moon, check out our Moon Phase Calendar.
Explore the universe through binoculars or a telescope and take in these gems of the May sky:
- M41 (NGC 2287) – is a bright open star cluster in Canis Major. M41 contains approximately 100 stars and there is some debate over their age with estimations ranging from 190 million to 240 million years old. The cluster is about 2,300 light years away.
- Carina Nebula (NGC 3372) – visible to the unaided eye and spanning more than 300 light years, this nebula is one of the largest and brightest star forming regions in our sky. Within the Carina Nebula is the star Eta Carinae, a binary system that is one of the most energetic in the region. Next to Eta Carinae is the Keyhole Nebula (NGC 3324), a molecular cloud of gas and dust and an active star forming region that looks, as the name suggests, like an old-fashioned keyhole. The Carina Nebula is about 7,500 light years away.
- The Jewel Box (NGC 4755) – is an open star cluster approximately 10 million years old. It is close to Beta Crucis (Mimosa), the second brightest star in the Southern Cross and in binoculars and small telescopes appears as an ‘A’ shape. It is about 20 light years across, consisting of just over 100 stars most of which are blue, as well as some red and blue supergiants. The Jewel Box is one of the youngest open clusters in our skies with and estimated age of approximately 14 million years. It lies about 6,400 light years from us.
- Alpha Centauri – a triple star system consisting of Alpha Centauri A and B and the closest star to our Sun, Proxima Centauri (Alpha Centauri C) at 4.2 light-years away. Proxima Centauri is a red dwarf star, only visible through large telescopes, and revolves around the other two stars once every 550,000 years. Two planets have been confirmed in orbit around Proxima, Proxima b and Proxima c. Proxima b is an Earth-mass planet discovered in 2016 located within the habitable zone of Proxima Centauri, while Proxima c is a super-Earth exoplanet orbiting the star once every 1,097 days.
- Omega Centauri (NGC 5139) – is the brightest and largest globular cluster in the sky. It is so bright that it was labelled as a star on early sky charts by Ptolemy and is one of the few objects in the sky that carries both a star designation and an object catalogue designation. Omega Centauri shines with the luminosity of a million suns and is relatively close to us, only 15,800 light years away. It contains about 10 million stars and some theories suggest it could be the remnant core of a galaxy that is merging with our own Milky Way.
- Centaurus A (NGC 5128) – is the most prominent radio galaxy in the sky. In visible light Centaurus A looks like an elliptical galaxy with a dark dust band intersecting its middle. There is evidence of a past collision or galaxy merger from the warping of this disk of gas and dust. There is also a black hole at the galaxy’s centre that ejects jets of high-speed gas into space. Centaurus A is about 12 million light years away and over 60,000 light years in diameter.
In May 2021 also look for:
- Total Lunar Eclipse – On the evening of May 26 the Moon will pass through the Earth’s shadow. It is also a supermoon on this evening. The eclipse will be visible throughout Australia and New Zealand with the partial eclipse beginning at 7:45pm Australian Eastern Standard Time (AEST). Totality will be from 9:09pm to 9:28pm (AEST) and during this time the Moon will take on a light coppery hue. After totality the Moon moves out of the Earth’s shadow and the partial eclipse ends at 10:53pm (AEST). You will not need any special equipment to see the eclipse – just your eyes (and clear skies)!
- Purchase the 2021 Australasian Sky Guide by Dr Nick Lomb, featuring an annual report of what’s in the sky and the latest astronomical findings. Produced by MAAS Media.
- View the May Sky Chart, which shows the stars, constellations and planets visible in the night sky from anywhere in Australia
- Check out these resources for getting started.