To help you learn about the southern night sky, Sydney Observatory provides a guide and a sky map or chart each month. This month’s guide is presented by Geoffrey Wyatt, Sydney Observatory’s Education Program Producer.
See the Sky Chart
We provide a June 2018 night sky chart (PDF) which shows the stars, constellations and planets visible in the night sky from anywhere in Australia. To view PDF star charts you will need to download and install Adobe Acrobat Reader if it’s not on your computer already.
Read the Guide
Geoffrey Wyatt: Hello there, my name’s Geoffrey Wyatt. I’m one of the Education team here at the Museum of Applied Arts Sciences’ Sydney Observatory, and I’m going to be talking to you about what’s in the sky for the month of Junius, the fourth month of the old Roman calendar as created by Romulus around 735 BC. After Julius Caesar’s last year of confusion and reform in 46 BC, it became the sixth month of the year, June.
This audio guide, the transcript and printable sky map are all available free from our website at www.maas.museum.
I recommend that you use a printed sky map to help you navigate through the night sky. You could use the free downloadable one from our website, or one from the Sydney Observatory book, ‘The Australasian Sky Guide’, by Dr Nick Lomb. I’ll give more details about that at the end of the podcast.
In my opinion, the month of June each year is the best time of the year to go outside, as long as it is clear and you are warm, to look up and enjoy the view of the Milky Way as the bright centre around Scorpius and Sagittarius rises in the East and passes overhead.
As we head toward the longest night of the year, the winter solstice, clearly you’ve noticed it’s cold. If you’re going outside to look at the stars, you will need some supplies. The obvious ones are a blankie to sit on so you don’t get wet. A red torch for the star map, this podcast as your celestial guide and perhaps a cup of tea or a hot chocolate.
What’s really important is that you find yourself a vantage point, somewhere where you’ve got a clear view to all four cardinal directions on the horizon, North, East, South and West. I know that sounds obvious, but many of us live next to big buildings, trees, hills, in valleys – and that can severely limit what you can see and enjoy.
You’ll also need, some would argue, the second most powerful tool in the Universe after mathematics and that is, imagination. When you look at the patterns in the sky, some of them are obvious, many are not. Imagination will unlock the patterns and bring the stories alive.
So we’re warm, we’ve got supplies. Are you ready to go?
Wait for sunset, then a little bit longer, and a little bit longer, until it’s relatively dark. A slight hint of twilight in the West is okay, and that’s a good thing, because that will help you orient yourself and get the right positions.
To begin I want you to turn due West or an azimuth of 270 degrees. Azimuth? An angle measured in degrees starting due north and then moving in a clockwise direction as seen from above. Have you got it? Good. North is therefore zero degrees azimuth.
Turn to your right a quarter of a turn. You should be facing east; it has an azimuth of 90 degrees east of north. Do another quarter turn. You should be facing south, an azimuth of 180 degrees. Turn to your right one more quarter turn; you’re now facing west, an azimuth of 270 degrees.
That’s easy. How about upward from the horizon? Well, directly overhead at zenith is 90 degrees. Halfway up, 45 degrees. The first object I want you to have a look at is an azimuth of 270. OK, good, we’re facing west. But 20 degrees above the horizon? How can you do that?
Simply hold out your hand at arm’s length as far as you can stretch. Hold out a pinkie. Now that pinkie measured against the sky will be roughly 1 degree or twice the size of the full moon. Now clench your fist. That’s 10 degrees against the sky. Lastly spread your hand from pinkie tip to thumb tip for about 20 degrees, and it doesn’t matter how old you are, how tall, how short, whatever. It’s all roughly in proportion.
What you will see is Sirius the brightest star in the night sky at 8.6 light years away, it’s about twice the mass of the Sun, nearly twice as wide but about 25 brighter.
By the way, a light year is the distance that light travels in one year in the vacuum of space. It’s a long, long way. For those of you that like numbers, its 9.4607×1015 metres or 9.5 thousand billion kilometres, both of which are meaningless to me. It’s a long way but don’t take my word and for it try this. It’s 300,000 kilometres per second in the vacuum of space. Multiply that by 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, and 365 days in a year. This will give you the distance that light travels in one year, in the vacuum of space.
If Sirius is 8.6 light years away, that means we see it – as it was 8.6 years ago. You’re looking back in time and Sirius is a relatively close star, but for other objects, goodness me you’re looking back so far, you’re seeing them at the time of the dinosaurs and beyond! Sirius, setting in the West, the brightest star in the constellation of Canis Major the big dog.
Constellation, you’ll hear me mention this a few times. A constellation is simply an area in the sky something like a like a sky suburb, a signpost, a group of stars that helps us find our way. They’ve been used for a long, long time. We now have 88 of them officially but for some their origins possibly go back maybe 6,000 years or longer.
By the way, the Egyptians used to look at Sirius and work out the length of the year. From many years of observation, they were able to work out, on average that the length of the years to be 365.25 days which is just an error of 11minutes of what we accept now for the tropical year. Very impressive considering how long ago they did that.
From Sirius, turn to your right ever so slightly so that you’re heading toward the north-west. You should be able to see another reasonably bright star close to the horizon. That star is called Procyon or Proc-y-on. It’s the brightest star in another group of stars called Canis Minor the smaller of the two hunting dogs.
Canis Major and Canis Minor they are the dogs that used to go with Orion the mighty hunter. He’s already well and truly set in the west, and we won’t see him for several more months in the evening sky.
Continue now towards the North-West a little bit more. You’re going to pass through the faintest of all the Zodiac constellations – that is, the path of the animals that most of us are familiar with, our birthday star signs if you like.
This particular constellation is really, really hard to see at the best of times. Trying to see Cancer right now? Forget it. I don’t think you’ve got much of a chance which is a shame.
A little bit more to your right, at an azimuth of roughly 320 degrees and an altitude of about 30 degrees which is one hand span and once clenched fist up, you’ll see a group of stars that with a little imagination, or perhaps a lot, you may be able to see an upside-down question mark. Can you see it? You might need the map. Look for the question mark which is part of a figure that looks like a cat. What you’re looking for is perhaps one of the oldest of all the constellations. Leo the lion.
The brightest star that you should be able to see at this particular point as I mentioned, about 30-35 degrees above the horizon, is the little king, Regulus. It’s a star that’s about 79 light years away, so again you’re seeing it now as it was 79 years ago. You’re looking back in time.
The Greek astronomer Claudius Ptolemy looked at this group of stars from Alexandria Egypt, around about 150 CE and included it in his book, the ‘Almagest’ where he listed 48 constellations. Ever since then, we’ve used those and tagged on a few extras to come up with 88 that we have now.
As we leave Leo the lion and head up to the next of the zodiacs Virgo and its neighbour Corus both are rich with small faint but visible galaxies though finding them is a little beyond our scope here and you would need a good telescope of at least a 100mm in diameter to see them.
From Corvus which to me looks a little like a shopping trolley if you play join the dots, go back down a little bit toward the constellation of Virgo with its one bright star, the 15th brightest in the night sky called Spica. This star is about 260 light years away. It’s certainly bluish white. It’s quiet dazzling. It’s about 10 times the mass of the Sun and 7 times its diameter. It’s a very hot, bright star.
You’re in the constellation of Virgo. This is the home of…at the moment, I should say, because I want to emphasize that things change, the home of the Autumnal equinox, but that’s a northern hemisphere event.
For us in the south it’s the home of the spring equinox. Until the year 2020, the spring equinox will occur on the 23rd of September. Do you need a quick refresher? That’s when the Sun crosses the celestial equator from the northern hemisphere, back into the Southern Hemisphere, heralding the start of spring in the south. Don’t forget the tilt of the Earth is the reason for the season. If the Earth wasn’t leaning to once side by 23.5 degrees we wouldn’t have any seasons, boring!
Virgo, goddess of justice. To the ancient Greeks, she was the goddess of the harvest, as well as justice. She would use her scales to weigh good and evil deeds. Legend says that she became so disenchanted with our behaviour that she threw away the scales and returned to her home in the sky.
To the ancient Egyptians, she was the Goddess Isis, who formed the Milky Way by dropping heads of wheat across the sky. There are so many stories about the stars at night and I love them all.
Leaving Virgo high in the north we now start to head toward the eastern sky and the next zodiacs and with this one I must talk about with a heavy heart. This group of stars was briefly associated with Julius Caesar. It showed Julius Caesar holding the scales of justice but this was dropped. In more modern Arabic culture, apparently it is not correct to draw a representation of a person. So, on many star maps, the figure of Julius Caesar holding the scales was dropped and it returned to the older group of stars, simply the Scales of Justice.
To the ancient Egyptians, these were the scales that would measure your heart after you had died and that’s where the expression ‘a heavy heart’. If your heart was heavy with bad deeds, then you weren’t in for a good time in the afterlife, but if not, you’re ready to pass through to the afterlife with safety.
This group of star is quite clearly Libra the Scales. That is the only one of the zodiacs which is not a living animal. It’s not particularly noteworthy apart from the fact that at one stage, it was also associated with the next of the zodiac along, Scorpius.
Libra while not bright does have stars with some rather cool names. Roughly 40-50 degrees above the horizon at the moment, we have at the moment, Zubenelgenubi, the Arabic name (I might not have pronounced it correctly), which means the southern claw of the scorpion. Zubeneschamali, roughly 35-45 degrees above the horizon, means the northern claw of the scorpion.
There’s not much else to see here so let’s continue down towards the east and galactic central near Scorpius which is coming up high enough now to have a look at depending on what time you’ve started this tour.
As the night goes on, you will see more and more of this group of stars that looks like a scorpion if you use a little bit of imagination, or perhaps an old fashioned ice pick. All sorts of different representations have been made.
There should be one star that is slightly reddish, it’s the 15th to 16th brightest star at night as it changes brightness, so we call it a variable star. It’s not traffic light red. It’s not ruby red. It’s more of a golden orange reddish hue. This star because of the fact that the planet Mars goes past relatively close by every 780 days or so is called the Rival of Mars, anti-Mars, anti-Aries, Antares.
It is the brightest star in the constellation of Scorpius and is its heart. By the way, it’s not ‘Scorpio’. That’s its astrological name. For us astronomers: Scorpius. This star is about 550 light years away. It’s about 15 times the mass of the Sun and about 700 times its diameter.
From Earth all these stars we see look like little points of light, but when we start to consider their size the Universe is enormously big and some of the objects in it, wow – huge!
If you have a look at Antares from a dark location on a moonless night when it’s up a little bit higher you may be able to see less than one degree away, or the width of one pinkie held at arm’s length, a little fluffy lump of light. That’s what we call a globular cluster.
It’s the fourth object in the Messier Catalogue, so it’s simply called M4. It’s a group of very old stars tightly packed together. It is well worth a look even through a small pair of binoculars. It’s reasonably close by at about 7200 light years away and is thought to be about 12 billion years old!
Continue along toward the tail of Scorpius, there’s two other little clusters up there but very different to M4. What we’re looking for here are young clusters, M6, the Butterfly Cluster of about 80 stars, they’re less than 100 million years old. In stellar terms they’re very young indeed. There’s another group called M7. Both of these open clusters are young, there’s not very many of them, they’re relatively close by. Globular clusters like M4 are old, lots of them jammed together and they’re typically further than open clusters.
If your view toward the south-east is clear enough and dark enough and you’ve waited long enough as we’ve been doing this rather long tour of the June night sky, you may start to be able to see a group of stars that looks a bit like a teapot.
It is Sagittarius, the Archer, half man, half horse with a bow and arrow and the arrow pointing at the heart of scorpion or the star Antares. Good luck trying to see all of that one.
The intriguing thing about this part of the sky is that it’s the home to the centre of the Milky Way, Via Lactea, meaning by milk, our galaxy. Roughly 26,000 light years away, in this direction lurks a black hole that is about four million times the mass of the Sun and it’s called Sagittarius A* (pronounced Sagittarius-A-star). You can’t actually see it but it’s a beautiful part of the sky to look at.
Well, now that you’re facing east I want you to turn to your right. That means we’re heading toward the south. Go around to the south and you’re looking for what is the smallest and perhaps the most famous and beautiful of all 88 constellations.
Yes, I am somewhat biased. From here in the southern hemisphere we get the best view of the Milky Way as the Earth is leaning to one side by 23 and a half degrees. That means the centre of the galaxy passes almost overhead and what we are looking for here is a quite close by, it is the bright small constellation Crux though most of us call it the Southern Cross. Fairly high up, roughly 60 degrees, so that’s three hand spans, you should be able to see that traditional beautiful cross of stars.
Did you know that the Southern Cross at any time of the night and year can help you find direction? If you draw a line, an imaginary line in the sky from the top of the cross through the bottom and multiply that by four and a half times its length, you come to what is a fairly empty part of the sky.
Well, it’s not that empty. There is a star there called Sigma Octantis and that’s our South star in the sky. From there, simply drop straight down to the ground and there you have south.
One of the most important uses of the stars for thousands of years has been to work out direction for navigation. If you face south, then directly behind you – north. To the left where the stars come up, east. Where the stars go down to your right, west.
Look at the Southern Cross, high in the sky. Starting at the bottom with Alpha Crucis or A-Crux go in a clockwise direction to the next one, Beta Crucis, if you have a small telescope or a very good pair of binoculars, centre on that star. But you need to have it on tripod to make it nice and steady. Look at that star Beta Crucis. Right next door to it, in fact snuggled up against it, sometimes lost in the glare is what we call DY Crucis perhaps the reddest star in all of the night sky. It’s a carbon star. It’s a very old star as far as stars go. Its atmosphere is very rich in carbon. Not so much in oxygen. As a result it takes on this ruby red appearance. It’s hard to see but well worth a look but remember you can’t see it with the naked eye, you do need a telescope or a visit to an observatory with telescopes like…Sydney Observatory of course.
If you’ve also got Beta Crucis in the centre of the eyepiece of your binoculars or small telescope, scan a little bit further away and look for an object called NGC 4755. NGC well that simply means the New General Catalogue object number 4755. Most consider the Pleiades or M45 to be the best open cluster but this has to be the second best. It contains about 100 stars around 14million years old, so they are very young. They’re about 6,000 light-years away and through binoculars or a small telescope, you may even notice a few of the stars that takes on a bit of colour. Most are white but some have a blue hue to them and one of them is clearly orange-red.
To one very famous astronomer, Sir John Hershel a few hundred years ago he looked at this and made a note in his diary, “This looks like a fine piece of jewellery laying out on velvet.” Ever since then, we’ve referred to this group of baby stars as the Jewel Box. It’s well worth a look. It’s very pretty.
Open clusters like this are pretty much the closest thing we have to a controlled stellar environment. They’ve been formed from the same cloud of gas and dust so they have the same chemical composition. They’re about the same age and about the same distance. The only significant variable is that of mass and that is a very important one.
Remember I mentioned a moment ago one of the stars is slightly orange-red? For such a young star of around 14 million years or so this means it’s big and it’s dying. It will probably explode soon as a supernova. We don’t know when. It’s possibly got only a few million years left but that’s about it, and then…BANG!
Snuggled up against the Southern Cross is a dark region of the sky that we commonly call the Coal Sack. Some Indigenous communities look at dark patches in the sky and use those to illustrate an idea or a story. Most of us look at the brighter the dots, the bright regions but here you have a dark patch against the Milky Way and with a little bit of imagination extending back towards Scorpius it looks like an emu. You might need a picture to see it but there are plenty of them available on the Internet. Once you’ve seen it you’ll never miss the emu again.
Going back to the sky and toward the Southern Cross you’ll be able to see the famous Pointers, Alpha and Beta Centauri. They are the two brightest stars in the constellation of Chiron the Centaur who was a very kind old teacher. In fact he was the teacher according to some legends of Hercules, Jason and Achilles. The two bright stars that just I’ve mentioned represent his front feet. Seeing the body of the centaur is pretty tough so you’ll need a good imagination and perhaps a star chart to see this one as well.
Alpha Centauri is the closest star after the Sun at just 4.3 light years away. Through a telescope, you’ll actually see that it’s two stars but they are getting harder to split as their gravitational dance of 80 years around each other is currently bringing them close together as we see them.
Quite close by but still in the constellation of Centaurus we have perhaps one of the finest objects in the night sky that I think you can see.
It’s just visible to the naked eye under ideal conditions but through any optical aid, you’ll be able to see NGC 5139 or Omega Centauri. It was discovered by Edmund Halley in 1677. It’s roughly a million stars grouped together in what we call a globular cluster. Much, much better than M4 that I mentioned earlier in Scorpius. It’s about 16,000 light years away. The stars are so close together in the cluster that the average separation is about 0.1 of a light year but in our region of the Milky Way the stars are on average about 4 light years from one another.
It’s a very densely packed region of the sky and only recently some ideas have come about that this in fact the core of an old galaxy that is now merging with our own, the Milky Way. Omega Centauri is one of the finest objects you can see through a telescope, but again you need to get away from the polluted skies and preferably when there’s no Moon.
From high in the south, where we’re looking at the moment go around the constellation of the Southern Cross and Centaurus, I want you to turn toward your right, so we’re heading toward the south west. We’re looking into what was the largest of all constellations, Argo Navis, the ship that carried Jason and the Argonauts in search of the Golden Fleece. Yet another one of these stories from the northern hemisphere.
That constellation was deemed too big, so astronomers broke it up into smaller groups or constellations. Carina the keel, Vela the sails, Puppis the deck, Pyxis the compass. The whole region is absolutely perfect for viewing with binoculars or a small telescope.
There are so many things that we can see as we go along this part of the sky. Move from the Southern Cross, and just below it and to your right you may be able to see a faint group of stars that makes up a long skinny cross. That’s what we call an asterism, or a false constellation.
That’s a group of stars that we often refer to as the Diamond Cross and yet again you may need the map to help. Just above the Diamond Cross scan for the Carina Nebula. It’s just visible to the naked eye under good conditions. It’s a cloud of hydrogen and helium, the two most abundant elements in the Universe.
What you’re looking at is the birthplace of stars and soon the death of at least one. This cloud of gas and dust is being bathed in ultraviolet radiation from young hot stars from within and they’re effectively lighting it up. Within the heart of this cloud there is one star called Eta Carinae. Eta Carinae is what we call a cataclysmic variable star. It’s a star at the end of its life. In the 1840s it started to brighten. By 1843 it got so bright, it was the second brightest star in the night sky. We’re seeing it in its final death throes. In 1843 it shed more mass than our Sun. That matter is now obscuring the star, making it harder to see. But shortly, very shortly indeed it can do one thing… (pop) explode as a Type II supernova. Look, it’s probably not going to happen today, but it might. It might happen tomorrow, a thousand years or perhaps a million years and if you’re a betting person and you want to take a bet on the most likely star to explode during your lifetime, this is it.
By the way, don’t worry about it. It cannot possibly hurt us from a distance of between 7 and 8,000 light years.
As we go around towards the south-west, getting low, about 20-30 degrees or 1 outstretched hand and one fist above the south-west horizon we have the second brightest star in the night sky, Canopus, it is the brightest in the constellation of Carina the keel. It’s 310 light years away, 8 times the mass of the Sun and 71 times its diameter, so it’s a very big star. Some older fisherman from Japan used to call this star ‘Nagai-ki’ or the long-life star as its beauty and brightness would bring joy and was thought to extend life of sailors that sailed south from Japan.
Special events for the month of June 2018 and let’s start with the Moon.
Last quarter is at 4:32am on Thursday the 7th
New Moon is at 5:43am on Thursday the 14th
First quarter is at 8:51pm on Wednesday the 20th and,
Full Moon at 2:53pm on Thursday the 28th of June
The Winter solstice occurs in the constellation of Taurus the bull at 8:07pm on Thursday the 21st of June. The winter solstice is when the Sun has reached it most northerly point in the sky, as we see it, and starts to move back toward the equator and the southern hemisphere.
If you’re fast you will catch the fleet footed Mercury low in the north-west just after sunset for the second half of the month moving from the constellation of Gemini to Cancer. It’s not very bright and never far from the Sun so you need a very clear view toward the west, good luck.
Venus is very bright in the north-west with only the Moon being brighter and moves through three constellations from Gemini to Caner and then Leo. On the 16th the young crescent Moon will be to the left and down just a tad.
Jupiter the giant of our Solar System is nicely placed throughout the month being high in the east shortly after sunset in the constellation of Libra near the star Zubenelgenubi. On the 23 and 24 the gibbous Moon is nearby. While Jupiter was at its best for the year last month it is still a stunning view through our telescopes so come along and take a peek at this gas giant and its family of moons.
For the first half of the month Saturn is very low in Sagittarius rising around the time of sunset. It will be at ‘opposition ‘on the 27th which means it is directly the opposite the Sun with us in the middle. The best time to view it is therefore around midnight. On the night of the Full moon, Jun 28 the Moon will be just below Saturn.
At the start of the month rising at 8:45pm and by 7:05pm by the end of the month is the planet named for the Roman God of War and that is Mars. It will nearly double in brightness over the month as it heads toward a favourable opposition next month which is something that occurs roughly once every 15 years. Make sure you see Mars over the next few months through a good telescope if you can and it should be incredible. While it is not traffic light red it certainly has reddish hues and its brightness should be a clear signpost. On the morning on June 3 the waning gibbous moon will be nearby.
I hope you’ve enjoyed this tour of what’s visible in the southern sky for the month of June 2018. I know it’s been a long trek but there’s just so much up there to see at this time of year.
You can find our monthly sky guide and podcast on iTunes. If you want more detailed sky maps, information about sunrise and sunset, Moon and tidal information why not purchase a copy of our book the ‘Australasian Sky Guide’ by Dr Nick Lomb, it’s available from Sydney Observatory or the Powerhouse Museum shop and via our website.
It’s only $16.95 if you come in to get it from us. There is an additional charge for postage and handling if you do it online. Our website is www.maas.museum then follow the link to Sydney Observatory. Our web page has a galaxy of information about astronomy and visiting Sydney Observatory to see through our telescopes, visit our theatre and see the spectacular planetarium.
My name is Geoffrey Wyatt. I hope you’ve enjoyed this guide and we’ll see you again soon.