Our Night Sky: May 2023

Even though May brings long days and short nights, there is still plenty for us to see if we stay up late or even get up early. You’ll find the constellation of Virgo in the southern night sky. It is home to the Virgo Cluster, which contains over 2,000 individual galaxies, some of which are the brightest galaxies in our night sky, so grab a telescope and have a look for them. 

The Milky Way arching over Loch Sunart and Ben Resipole during a beautifully clear night in May

The Constellations

This month, the sun sets around 9:30 pm and the stars and the constellations start to become visible from about 11:00 pm onwards. If you look in the south-western sky at that time, you will see the constellation of Leo (the Lion). It was due south last month but has now been replaced by the constellation of Virgo (the Maiden). 

Virgo can be found by locating its brightest star, Spica, which will be low down on the southern horizon. If you cannot find it, then look directly overhead and you will see the Plough. Follow the curve of the Plough’s handle round, through the very bright star Arcturus and then down to Spica.

In some cultures, Virgo is the "Wheat-Bearing Maiden" or the "Daughter of the Harvest” and is depicted holding several spears of wheat in each hand. Spica is one of the ears of grain hanging from her left hand.

From Spica, trace a line up and to the right to find Porrima, Virgo’s second brightest star, which is the Maiden’s lower elbow. Go up from there to find Vindemiatrix, Virgo’s third brightest star and the Maiden’s upper elbow. ​Many other stars make up Virgo, but they are quite faint and may be difficult for you to pick out.

The Constellation of Virgo
Image Credit: Till Credner [CC Share Alike 3]

Virgo is home to a large cluster of galaxies known as the Virgo Cluster. This Cluster contains over 2,000 individual galaxies, 11 of which are Messier objects that will be visible to anyone using a reasonable astronomy telescope. All these Messier objects are galaxies and the most notable of these is M104, the Sombrero Galaxy. This edge-on spiral galaxy has a dark dust lane running across its centre, giving it the appearance of a sombrero hat. Other notable galaxies are M49, M58 and M61. M49 is an elliptical galaxy and is the brightest galaxy in the Virgo Cluster, M58 is a beautiful barred spiral galaxy and one of the brighter galaxies in the Virgo Cluster and M61 is a face-on spiral galaxy that is one of the largest galaxies in the Virgo Cluster.

Southern Night Sky - May
Created using SkyPortal Mobile App

Northern Night Sky - May
Created using SkyPortal Mobile App

Below Virgo is Corvus, the Crow. It is reasonably easy to find as it is a distinct, almost square set of stars right down on the horizon. Above Virgo, you will find Boötes (the Herdsman) and its brightest star, Arcturus. This star is easy to spot as it is the fourth brightest star in the night sky and has a noticeable golden tinge. It is part of the Spring Triangle asterism, which is formed by drawing lines from Arcturus to Spica, Spica to Regulus and Regulus back to Arcturus. Below and to the left of Virgo is Libra (the Scales), a very faint constellation with its main claim to fame being that it is the only constellation in the zodiac which doesn’t represent an animal.

The Moon

We start the month with a waxing Moon that becomes 100% full Moon at precisely 6:34 pm on 5 May. This means that it will appear full on the nights of 4-5 May, 5-6 May, and 6-7 May. It will rise in the south-east at around 8:00 pm on 4 May, at around 9:30 pm on 5 May and shortly after 11:00 pm on 6 May.

Many cultures refer to this month’s full Moon as the Flower Moon because of the abundant flower blooms that occur when Spring gets going properly. Other names include the Hare Moon, the Corn Planting Moon, and the Milk Moon.

The last quarter Moon (a half-moon) is on 12 May, and you will find it close to Saturn on the mornings of 13 and 14 May.

The new Moon (no moon) is on 19 May. This means that a few of days before, on 16 and 17 May, you should see the thinnest of crescent Moons sitting low in the east at sunrise, which will be about 4:30 am. Alternatively, a day later, on 20 May, you should be able to pick out the thinnest of crescent Moons sitting low in the western sky as the Sun sets. On the following evening, 21 May, a slightly thicker crescent Moon will be higher up in the western sky, sitting well below and to the right of Venus. The Moon will be higher still on 22 May, having moved to just below and to the right of Venus. On the following evening it will be between Mars and Venus.
 
We have a first quarter Moon (a half-moon) on 27 May, and you will find it high in the southern western sky, sitting beneath the constellation of Leo. Three nights before, on 24 May, it will be sitting just above and to the left of Mars.

The Planets

Just like last month, you will see a brilliantly shining Venus in the western sky as darkness falls. Playing its part as the Evening Star, Venus doesn’t set until well after midnight and it will be shining far brighter than anything else in the night sky, except for the Moon. On 22 and 23 May, you will find it close to the Moon, while on the last few days of the month, it will be close to Castor and Pollux, the twin stars of Gemini.
 
You will find Mars high up in the western sky as darkness falls, well above and to the left of Venus, initially in Gemini, but moving to the left of this constellation as the month progresses to eventually find itself in the constellation of Cancer. It will be visible for a good part of the night, before setting at around 1:30 am and on 24 May, it will be very close to the Moon.
 
Once Mars has set, you will need to wait until around 3:30 am to see another planet because that is when Saturn will rise above the horizon. You will find it in the eastern morning sky, sitting in the constellation of Aquarius. The Moon will pass beneath it on 13 and 14 May.
 
Neptune will rise in the east at about 4:00 am, but it will be difficult to see it because this outermost planet is very faint and may be lost in the morning twilight.
 
Jupiter reappears in the morning sky from about the middle of the month. You will find it low down on the eastern horizon at daybreak, shining brightly in-between Pisces and Aries. A crescent Moon will be close to it on the morning of 17 May.
 
Uranus and Mercury are lost in the Sun’s glare this month.

Meteor Showers 

The main meteor shower in May is the eta Aquariids, which is the result of small pieces of Halley’s Comet burning up in the Earth’s atmosphere. This year it is active between 19 April and 28 May, with the forecast to peak being between midnight and dawn on the morning of May 6, making this the best time to look for them. However, as there is no sharp peak for this shower, but rather a plateau of good rates that lasts a few days, then same time on May 5 and on May 7 will also be best for watching for them. Unfortunately, there is a full Moon on 5 May, meaning that bright moonlight will drown out all but the brightest meteors on these three nights. Given this, it may not be worth staying up until the wee small hours of the morning to try and look for them.
 
If you do decide to try and do spot some, they will appear to emanate from the constellation of Aquarius (The Water Carrier) at a radiant point near the star Eta Aquarii, although you don’t need to look there to see meteors as they’ll appear across the whole night sky. Start looking for them shortly after 3:00 am because this is when the radiant point is above the horizon. Bear in mind that the higher the radiant point gets in the night sky, the greater the number of meteors you should see. Sunrise is at around 5:30 am, so this gives you an hour or so to spot them. At its peak, on a moonless night, around 10-20 meteors per hour may be spotted.