To help you learn about the southern night sky, Sydney Observatory provides an audio guide/podcast, transcript of that audio, and a sky map or chart each month. This month’s guide is presented by Geoffrey Wyatt, Astronomy Educator at Sydney Observatory.
Geoff’s enthusiasm and humour are captivating but based on sound science, and enriched with stories of historical and cultural aspects of astronomy, including Indigenous and Greek myths. According to some Indigenous communities, there is an Emu in the sky (see picture, below).
Geoff reckons that June is a great month to see the brightest part of the Milky Way high overhead. So go on, get a blanket and a torch with red cellophane on the front, your free sky chart and audio (below) and go outside, and look up at the wonder of the Universe.
SEE THE SKY CHART
We provide an embedded sky map (below) and a June 2014 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.
BUY THE BOOK
Our annual book, ‘The 2014 Australasian sky guide’, by Dr Nick Lomb has more information and star maps for months from December 2013 until December 2014 inclusive, plus information about the Sun, twilight, the Moon and tides, and a host of other fascinating astronomical information. You can purchase it ($16.95) at Sydney Observatory and Powerhouse Museum shops or other good bookshops, or online through Powerhouse Publishing (additional packing/postage costs apply).
READ THE TRANSCRIPT (after the jump)
Transcript of the June 2014 monthly sky guide audio
Geoffrey Wyatt: Boodyeri kamaru. That’s “Hello there” in the language of the Gadigal people of the Eora nation, the traditional custodians of the land upon which Sydney Observatory was built in 1858.
My name’s Geoffrey Wyatt. I’m the Education Officer here at Sydney Observatory, and I’m going to be talking to you about the month of Junius, the fourth month of the old Roman calendar, as created by Romulus around 735 BC.
Of course, 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.sydneyobservatory.com.au/monthlyskyguides.
We recommend that you use a printed map to help you navigate 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. We’ll give you 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’s clear and you’re warm, to look up and enjoy the view of the Milky Way as it rises in the east and passes overhead.
As we head toward the longest night of the year, the winter solstice for us in the Southern Hemisphere, clearly you’ve noticed it’s cold. If you’re going outside to look at the stars, you need some supplies.
The obvious ones are a blankie to sit on so you don’t get wet. A torch, hopefully one with red cellophane on the end so the torch shines red light (but don’t get the water soluble stuff) so you can read the star map and any notes. You might need a hot cup of tea or Milo.
What you need to do is to find yourself a vantage point, somewhere where you’ve got as clear a view as possible of all four cardinal directions, north, east, south and west. I know that sounds obvious, but many of us live next to big buildings, trees, hills, valleys – we don’t get a clear view.
But to get the best advantage from the sky guide, the higher you are, the more of the horizon you see, the better.
You’ll also need, perhaps, some would argue, the most powerful, the second most powerful tool in the Universe, and that is imagination. Because when we look at these patterns in the sky, some of them are obvious. Some would say, many are not. Imagination, we’re warm, we’ve got supplies. Are you ready to go?
Wait for sunset, a little bit longer, a little bit longer, until it’s relatively dark. A slight hint of twilight in the west is OK, and that’s a good thing, because that will help you orient yourself and get the right positions.
What I want you to do is turn to an azimuth of 270 degrees. Azimuth. Let’s run through that very quickly. Astronomers like to find positions in the sky. Of course, we could say, “Over there, by the tree, to the left,” or “Up”. But unless you’ve got the same reference point, that doesn’t work. So we need a way of doing it.
We’re going to use azimuth, an angle that we measure in a clockwise direction as seen from north. Find north. Got it? Good. We can say that’s 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 upwards from the horizon? Well, directly overhead at zenith is 90 degrees. Halfway up, 45 degrees. But 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 1 degree, or twice the size of the full moon. Clench your fist. That’s 10 degrees against the sky.
Now, spread your hand from pinkie tip to thumb tip is about 20 degrees, and it doesn’t matter how old you are, how tall, how short, whatever. It’s all in proportion.
Look west, one hand span above the horizon. You should be looking for the brightest star in the night sky. His name is Warepil. Warepil? Yes. Don’t forget that people from all around the world have different names for different objects.
This is a great time to point out that the oldest star watchers, possibly on this planet, are the Indigenous people of Australia. To the people of north-western Victoria, the Boorong clan of the Wergaia language group, this star is a chief of the group of gods that we now refer to as the Nurrumbunguttias.
The ‘old spirits’ is perhaps a better way to describe them. The old spirits went into the sky. The Milky Way that we now see is the smoke from their campfires. We call that Warring.
This particular star is one of the chiefs. His name is Warepil. But to you and me, he’s more commonly known as Sirius the Dog Star, the brightest star in the night sky.
This star is not as bright as you would have seen it some time ago because it’s getting very low in the western sky. This is not a good to see it, but we use it as a signpost.
It’s 25 times the mass of the Sun. It’s a pretty big star. It’s 8.6 light years away. Remember that a light year is the distance that light travels in one year. It’s a long, long way. For those of you who like numbers, it’s about 9.5 billion thousand billion kilometres. It’s a long way.
If you want to work it out, 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, 365.25 days per year on average. That will give you the distance of one light year.
This star is 8.6 light years away. That’s roughly how we see it – as it was more than 8.5 years ago. You’re looking back into time. For this, it’s relatively close by, but for other objects, goodness me. You’re looking back so far, you’re seeing them as they were at the time of the dinosaurs. Sirius, setting in the west, brightest star in the constellation of Canis Major.
You hear me mention this time and time again. A constellation is simply like a suburb in the sky, a signpost, a group of stars that help us find our way. They’ve been used for a long, long time. We now have 88 of them, officially. The oldest ones probably go back maybe 4,000 years or so.
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, as I just mentioned, 365.25 days.
They didn’t really understand decimals. In fact they didn’t have decimals. But I’m sure anyone can figure out a quarter. Imagine a cake.
You can cut it in half, you can cut it quarters. You may be able to cut it into thirds. When you start to get down to the very small fractions, which we commonly use as decimals, that’s trickier. But a quarter? A piece of cake, one might say.
The Egyptians worked out, thousands of years ago, the accuracy of the year to within 11 minutes of what you and I accept it now. I think that’s truly amazing.
Look at Sirius. We’re going to say farewell. Turn to your right ever so slightly so we’re heading toward the north-west. There should be another reasonably bright star close to the horizon.
That star is called Procyon. It’s the brightest star in another group of stars called Canis Minor, the smaller of the two hunting dogs.
Canis Major, 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.
Continue now towards the north-west a little bit more. You’re going to look for a group of stars, the faintest of all the constellations of the zodiac – 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 chance, which is a shame. It’s an interesting group of stars because the picture is so old.
The picture of these stars, of a crab that slides sideways, used to be so important to the people of Mesopotamia thousands of years ago, maybe as far back as 4,000 BC.
This was the part of the sky that the summer solstice for the Northern Hemisphere used to occur in, but no longer. The Earth does something rather unusual. It does a 26,000-year wobble, which we call the precession of the equinoxes.
Things change ever so slowly. Cancer? Nah, you’re not going to be able see it now. It used to be a marker in the sky for the summer solstice for those in the Northern Hemisphere, but no longer.
Towards the north-north-west, a little bit more to your right, at an azimuth of roughly 320 degrees and an altitude of 40 degrees. That’s two hand spans. Look up. You’ll see a group of stars. With a little imagination, or perhaps a lot, you may be able to see an upside down question mark. Can you see it? You’ll need the map.
The question mark isn’t shown on the map, which makes it a little confusing. Look for a figure on the map that looks like a cat. What you’re looking at is perhaps one of the oldest of all the constellations. It is Leo the lion.
The brightest star that you should be able to see at this particular point. As I mentioned, about 40 degrees above the horizon, is the little king, Regulus. It’s a star that’s about 79 light years away, so you’re seeing it now as it was about 79 years ago. You’re looking back into time.
Some of us call this star the second of four Royal Stars. Thousands of years ago, for Mesopotamia, this star, Regulus, was seen as the brightest star near the summer solstice that I mentioned, which occurred in Cancer the crab, which didn’t have any bright star. This was the nearest bright star.
They used this star as a marker. They called it a Royal Star. Of course, it’s no longer a marker, because the solstice and the equinoxes have moved, but historically, this star is important.
It’s part of the question mark. Look for an upside down question mark. Perhaps some people see a sickle, an old-fashioned instrument used to cut grass or cut wheat. It’s pretty easy to see if you spend a bit of time.
That whole part of the sky, Leo the lion. We know it’s old. We know it was mentioned in the 8th century BC by the poet Homer in his fabulous poem, the ‘Odyssey’. It’s another one of these constellations in what we call the zodiac, the circle of the animals.
We know Claudius Ptolemy looked at this group of stars. He was a Greek. He lived in Alexandria, around about 150 AD. He included this in his book, the ‘Almagest’, where he listed 48 constellations. Ever since then, we’ve used those.
We’ve tagged on a few extras to come up to 88 that we have now. As we leave Leo the lion and head towards the next of the zodiac constellations, this part of the sky is absolutely ripe for the pickings if you have a small telescope or a very good pair of binoculars on a tripod.
Sadly, none of these next few objects are visible to the naked eye, but it’s worth a try if you’ve got a pair of binoculars.
Go from the tail, Denebola, of Leo the lion, and head towards the next constellation, Virgo. We’re actually after a star called Vindemiatrix, which means the ‘grape gatherer’. It’s not exactly the brightest star in this part of the sky, but you should be able to see it if you’ve got your star map.
In this region, there are around about 2,000 galaxies crowded together, up to a distance of about 65 million light years away. As far as telescopes go, you’d need something about 100 millimetres in diameter, and you should have a good eyepiece. I can’t stress enough.
You don’t need this stuff to explore the sky, but if you do have a telescope, make sure you’ve got a good eyepiece. It is, after all, half the telescope. Or a good pair 7 x 50 binoculars, preferably on a tripod mount.
If you scan this part of the sky, there are lots and lots of galaxies there. Some of them, M84, M86, M87, they’re simply red herrings, not to look at if you’re trying to spot a comet.
This was a catalogue developed by a Frenchman, Charles Messier, who made up a list of objects that you wouldn’t waste your time on if you’re trying to find a comet. We now actually use those as a bit of a signpost. Of course, they’re quite fascinating in their own right.
They are going to be dim, fuzzy blobs. That may not sound exciting, but if you’re away from the city, and there’s no bright lights, no pollution, and no Moon, and you see these through the telescope.
You are looking at hundreds of thousands of millions of stars clumped together, millions of light years away. Ooh, it’s so much fun. I love it!
Anyway, don’t spend too much time on there, because we’re really talking about a visual guide for the night.
If you go up a little bit from this point in time, before we go back to Virgo, go up a little bit higher. You may be able to see a group of stars that looks a little bit like a shopping trolley. Can you see it? It’s almost overhead, but not quite.
This group of stars represents the constellation of Corvus the crow. The crow used to be able to talk, according to some legends, but he was pretty lazy and didn’t do a good job, so the god Apollo eventually lost his temper, took away his ability to speak, and banished him into the sky.
As I say, to me, it looks like a shopping trolley, but historically, Corvus the crow. This area of the sky houses one of the easiest galaxies to see with a pair of binoculars. It’s called M104. It’s commonly called the Sombrero Galaxy because it looks like one of those huge hats.
It’s a little bit smaller than the Milky Way, but moving away from us at 1,000 kilometres per second, which is truly astounding.
It’s about 29 million light years away. It’s very small, but it is certainly well worth a look if you have a small telescope or a good pair of binoculars. M104, the Sombrero Galaxy, in Corvus the crow.
Go back down a little bit towards 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 seven times its diameter. It’s a very hot, bright star.
You’re in the constellation of Virgo. This is the home…at the moment, I should say, because I want to re-emphasize that things change. It’s presently the home of the autumnal equinox, but that’s a Northern Hemisphere event.
For us, it’s the home of the spring equinox. Until the year 2020, the spring equinox will occur on the 23rd of September. A refresher, that’s when the Sun crosses the celestial equator from the Northern Hemisphere, back into the Southern Hemisphere, heralding the start of spring.
Virgo, goddess of justice. To the ancient Greeks, she was the goddess of 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 behavior that she threw away the scales and returned to her home in the sky.
To the ancient Egyptians, she was Goddess Isis, who formed the Milky Way by dropping heads of wheat across the sky. There are so many stories about the stars in the night sky. I love it.
Before we continue along the ecliptic, and that’s the path of the Sun, the Moon, the planets where we’re looking at these main signposts, I suppose you could say, the zodiac constellations.
Before we go any further, I want you to go down a little bit. Now, we’re up and down, left and right, as we got across this tour of the sky. There’s so much to see this time of year. If you go about 25 degrees above the horizon, so go from Virgo, drop down towards the north, northeast, there’s a relatively bright star there.
We call it Arcturus, but through the Indigenous people that I mentioned before, the Boorong of the Wergaia language group, this star represents Marpeankurrk.
Marpeankurrk was a woman who discovered the rather, can I say, tasty wood-ant larvae. She taught people where to look for them. When the Indigenous people of that region of north-western Victoria saw this star, Arcturus, in the northern sky, they knew it was time to go and looking for wood-ant larvae. When they saw Arcturus setting with the Sun, they knew that the season for the ant larvae was coming to an end and summer wasn’t that far away.
After that little diversion, what we’re going to do is go back up to Virgo and head down along the ecliptic, this imaginary line that’s the path of the animals, if you like, towards the next of the zodiacs. That is one that I must talk to you about with a heavy heart.
This group of stars was briefly associated with Julius Caesar. It showed Julius Caesar holding the scales, the balance of good and justice, but this was dropped. In more modern Arabic culture, apparently it’s not correct to draw a representation of a person. On many star maps, the figure of Julius Caesar holding the scales, Julius was dropped, and it returned to the older group of stars, the Scales of Justice.
To the ancient Egyptians, these were the scales that would measure your heart after you had died. That’s where the expression has come from, ‘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 really have to pass through to the afterlife with safety.
It’s incredible how many of these expressions we have can be traced back to cultures from thousands upon thousands of years ago.
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 zodiac along, Scorpius.
As a result of being made its own constellation, the stars themselves have rather cool names. Roughly 40 degrees above the horizon, at the moment, you should be able to see Zubenelgenubi, the Arabic name (I might not have pronounced it correctly), which means the southern claw of the scorpion. Zubeneschamali, roughly 35 degrees above the horizon, meaning the northern claw of the scorpion, and Zubenalakrab simply meaning scorpion’s claw.
Those three stars are the brightest stars in that particular constellation. We go down towards the east and Scorpius is coming up high enough for us to have a look at. Depending on what time you’ve started your tour, you may not be able to see it all.
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 ice pick. All sorts of different representations have been made.
There should be one star clearly visible that is slightly reddish. It’s not traffic light ruby red. It’s more of a golden orange hue. This star, because of the fact that the planet Mars goes past relatively close by every 780 days. Is called the Rival of Mars, anti-Mars, anti-Aries, Antares.
It is the brightest star in the constellation of Scorpius. By the way, not ‘Scorpio’. That’s its astrological name. For us astronomers: Scorpius. This star is 550 light years away, about 15 times the mass of the Sun and 800 times its diameter.
To you and me, all these stars 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, when a Moon was not,on a moonless night when it’s up a little bit higher, you may be able to see right next to it, in fact less than one degree. One degree is the width of one pinkie held at arm’s length. You may be able to see a little fluffy lump of light. That is what we call a globular cluster.
It’s the fourth object in Messier’s 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.
If you go along towards the tail of Scorpius, there’re two other little clusters up there. They’re not as globular or round, spherical in terms of their clustering, as M4. They won’t spread out. This is exactly the opposite.
What we’re looking for here are young clusters, M6, the Butterfly Cluster of about 80 stars, ah look they’re less than 100 million years old. In stellar terms, they’re very young indeed.
There’s another group called M7. These are open clusters, young, not very many of them, relatively close by. Globular clusters like M4 old, lots of them jammed together and typically a long way.
If your view towards 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 sky, you may start to see a group of stars that looks a bit like a teapot.
It is Sagittarius, the Archer, a half man, half horse, with a bow and arrow and the arrow pointing at the heart of Scorpius or the star Antares. Good luck on that one.
Teapot, sure, I can say that. What is here in this part of the sky is the heart of the Milky Way, Via Lactea, by milk, our galaxy.
Roughly 26,000 light years away, in this direction near the south is the centre of the Milky Way. What lurks at the centre of the Milky Way? In fact, what lurks at the centre of most galaxies? Quite probably a black hole.
Here, we have a black hole that is about four million times the mass of the Sun. It’s probably a bit low to see at the moment, but wait a little bit longer until it gets up. Away from the city, if there’s no Moon, this is a beautiful part of the sky to look at.
Now that you’re facing east, I want you to turn towards your right. That means we’re heading towards the south. Go around towards the south and you’re going to look for perhaps the most famous of all 88 constellations.
Of course, I’m biased. I live here in the Southern Hemisphere. We have the best view of the Milky Way as the earth is leaning over to one side by 23 and a half degrees. That means we get a bit of view of the Milky Way.
What I want you to do is look for that small, bright constellation, Crux. Some people call it Crux. Most of us call it the Southern Cross. Fairly high up, roughly 60 degrees, so that’s three handspans, you should be able to see that beautiful traditional cross of stars. Not everyone sees it that way.
Over in New Zealand, the Maori say it is Te Punga, a boat anchor, apparently. To some Indigenous communities across Australia, it represents the footprint of a mighty eagle. To others it is the four unmarried daughters of a group elder. That’s from the Kanda people of Victoria.
I’d like to tell you a story that’s been documented by Katie Langloh Parker in 1896. We use this because the stories were passed on with knowledge they’d recorded and shared. It was done in a very sensitive and respectful way. We’re quite happy to share these stories.
This story comes from the Murri people of Northern New South Wales or south-eastern Queensland. It goes along the lines like this. There was a time when the Great Spirit Baiame walked upon the earth and he made three people, two men and one woman.
He told what animals and plants they could eat and which ones they could not eat. Above all, they were told they could not eat the kangaroo rat. Everything was fine and dandy for quite some time, but then, a terrible drought came.
Things started to die off. Food wasn’t so easy to find. They were getting hungry. One man and the woman came across a kangaroo rat and they killed it and ate it. They offered some to the other man, but he said “No, I can’t eat that. Baiame told me not to eat the kangaroo rat.” He walked off and left them.
The man and woman that remained behind continued to eat, but then they felt, “Gee, we should go after our friend.” They walked off after him, but they couldn’t catch up. They could see him walking out over the pebbly ground and over the hills. They saw him eventually standing by a big coolabah plain, next to a river. He kept walking. They called out to him, but he kept walking.
Then, he dropped dead by a big gum tree. Suddenly, the spirit, the Yowie appeared. There was a crack of thunder and they dropped to the grounds. They wouldn’t get any closer. They saw the Yowie lift the man’s body into the tree.
There were two cockatoos called mooyi in the tree and they flew off. We now see those in the sky as the pointers, Alpha and Beta Centauri, the two bright stars that point toward the cross.
The Yowie lifted the man into the tree and the tree started to rise up into the sky higher and higher. The cockatoos flew after it, chasing their tree.
Eventually, the tree became so small, so far away they couldn’t see it. What they could see were the eyes of the Yowie and the eyes of first man ever to have died. They got smaller as they got further away. They became the four brightest stars of what we now call the Southern Cross. The mooyi, the cockatoos, they’re seen as well chasing their tree back into the sky.
I love hearing stories like that from the Indigenous people of Australia. Most of us have grown up hearing stories from the north. We hear of Hercules. We go to see movies about the Titans and so on and so on. But there is now a renaissance of Indigenous sky lore in the Southern Hemisphere, and the more we learn, the more we share, the better.
There you have one story about the Southern Cross, but there are many from different communities. Please remember there is not a single Indigenous culture, but there are hundreds of communities across this land.
So, the Southern Cross: look carefully at it. At the moment, it’s very nicely positioned. You can use it to find direction. If you draw a line, and 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 appears to be a fairly empty part of the sky.
Well, it’s not empty. There is a star there. Unfortunately at magnitude 5.4, that’s a way we measure star brightness – that means the majority of people simply can’t see it. If you’ve got very good eyesight away from the city when there’s no Moon, you probably can see it.
That’s our south polar star. If you draw that imaginary line and you get to that point marked by the star Sigma Octantis, and that’s south 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, to work out direction for navigation. How to find south. If it goes directly behind you – north. To the left where the stars come up, east. Where the stars go down to your right, west.
A very important use of the stars, finding direction and, as I mentioned earlier when talking about Sirius or Warepil, working out the time of the year.
Southern Cross, high in the sky. As you go around from Alpha Crucis to the next one, Beta Crusis, if you have a small telescope or pair of binoculars, centre 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. Now, DY Crucis is not a particularly great or interesting name. Recently, however, by an Australian it’s been named Ruby Crucis. You will see this as perhaps the reddest star in the night sky. We call it 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.
If you’ve also got Beta Crucis in the centre of the eyepiece of your binoculars or telescope, scan a little bit further away and look for an object called NGC 4755. NGC, New General Catalogue.
Object number 4755. Not a terribly romantic name, but this is perhaps the second finest group of baby young stars, if you like, called an open cluster that we can see in the sky.
Most consider the Pleiades, M45 North, to be the best. This would be the second best. It’s roughly a hundred stars. They’re about 6,000 light years away, and through binoculars or a small telescope, you may notice a group of stars that takes on a bit of colour.
Most are whitish. Some have a whitish-blue hue to them. But one of them is slightly orange-red.
To one very famous astronomer, 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. Well worth a look. It’s pretty.
For those of you studying astronomy, open clusters like this are often used in exams because they’re pretty much the best thing we have or the closest thing we have to a controlled 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 variable is that of mass, and that’s a very important one.
Remember I mentioned a moment ago one of the stars is slightly orange-red? For such a young star, this means one thing only: it’s dying. It’s big, it’s dying, and soon, it will possibly explode as a supernova. We don’t know when.
It’s probably got millions, tens of millions, maybe even hundreds of millions of years go to, but in stellar terms, it’s not far away.
Now that we’ve got to the Southern Cross, it’s fairly high up, if the sky around where you’re viewing from is not nice and dark, can you see a little dark patch? Snuggled up against the Southern Cross is a dark region of the sky that we commonly call the Coal sack.
But once more, to the Boorong, if you look carefully, there seems to be a bit of a dark patch against the Milky Way running back towards Scorpius which by now is probably a little bit higher in the east. What you’re looking at is the Emu in the sky.
Some Indigenous cultures look at dark patches in the sky. Most of us look at dot to dot, the bright regions, but here you have a dark patch against the bright Milky Way that with a little bit of imagination, you’ll be able to see an emu.
Its head with its beak up against the Southern Cross. Its long neck passing back through Centaurus, back towards Scorpius where you’ll be able to see the body of the emu which is quite chunky.
You might need to look at a picture of it, and there are plenty of them available on the Internet to see. Once you’ve seen it, you’ll never miss it again.
And if you can, if you live in the Sydney region, make a trek north about 25 kilometres from Sydney to the Ku-ring-gai Chase National Park. Look for the Elvina Track. It’s only a few hundred metres, so it’s very close to convenient parking.
If you go into this national park, you’ll be able to see a carving, an Indigenous carving in the rocks of the emu. Theories are developing that this emu in the rock is actually matching the emu in the sky that I mentioned.
If you do go there and have a look at it, please, please, treat it with respect. Don’t touch it. Photograph it. Share it. Enjoy it, but look after it. It’s been there a long time, and we want it there for a lot longer still. The emu in the sky. It’s well worth looking for.
Going back towards the Southern Cross and the 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. He was the teacher, according to some legends, of Hercules, Jason and Achilles.
But the two bright stars that I’ve mentioned represent his front feet. Actual seeing of the centaur is pretty tough, so you’ll need a good imagination or a good old star chart to see that one.
Alpha Centauri is the closest star to us after the Sun at 4.3 light years away. Though a good pair of binoculars or small telescope, you’ll actually see that it’s two stars. The two stars are locked together in a gravitational dance that takes them 80 years to go around each other once.
Quite close by, 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 is 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 in Scorpius a little bit earlier. It’s about 16,000 light years away.
The stars are so close together that if you were in there, the average separation that you would be able to see is 0.1 of a light year, but out here in our neighbourhood of the Milky Way, the stars on average are about 4 light years away 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 may be the core of an old galaxy that is now merging with our galaxy, 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 pollution of the city. If you feel like a challenge, quite close by is yet another very interesting object only visible through a telescope or good binoculars, NGC 5128.
It was discovered by John Dunlop in 1826 from Parramatta, where the old government observatory used to be. This is actually, we think, two galaxies in collision. It’s about 15 million light years away, and it has a central black hole something like 55 million times the mass of the Sun.
It’s enormously big, enormously powerful, pumping out huge amounts of radio energy. It’s well worth a look. To the naked eye, you probably can’t see it, but through the telescope, you can see it. It’s a little bit of a smudge.
Through a bigger telescope, believe it or not, it looks a bit like a hamburger. From high in the south, where we’re looking at the moment, around the constellation of the Southern Cross and Centaurus, I want you to turn toward your right, so we’re going towards the south-west.
We’re looking into what used to be the largest of all the 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 to be too big, so astronomers broke it up into smaller groups, smaller constellations. Carina the keel, Vela the sails, Puppis the deck, Pyxis the compass. This whole region is absolutely perfect for viewing with binoculars or small telescopes.
There are so many things that we can see as we go along. Move from the Southern Cross, and below it and to your right a little bit, 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. Above that, look into that part of sky and what you’re looking for is the Carina Nebula. It’s a cloud of hydrogen and helium, the two most abundant elements in the Universe.
You will need binoculars or indeed a small telescope for this, by the way. What you’re looking at is the birthplace of stars and soon, possibly, the death of a star. This cloud of gas and dust has been bathed in ultraviolet radiation from the hot young stars within it, and they’re effectively lighting it up.
Within the heart of this cloud, there is a star called Eta Carinae. Eta Carinae is what we call a cataclysmic variable star. It’s a star that’s at the end of its life. Sometimes it’s brighter than others. It varying its brightness.
Sometimes bright, sometimes not so bright. In the 1840s, it started to get very bright. By 1843, it got so bright, it was the second brightest star in the night sky, and the Boorong clan that I’ve mentioned noticed this star become so bright.
They named it Collowgullouric War, meaning wife of War, the second brightest star in the night sky, Canopus in the constellation of Carina the keel. I’ll get to that in a moment.
This star is dying. What we’re seeing is the final throes, if you like, of its death. In 1843, it shed something like 30 times the mass of the Sun. Now that mass is now obscuring the star, making it harder to see. But shortly, very shortly indeed, that star can do one thing…
It will explode as a type 2 supernova. Look, it’s not going to happen today, but it might. It might happen tomorrow, a thousand years, a million years, but if you’re a betting person and you want to bet on the most likely star to explode during your lifetime, this is it.
By the way, don’t worry about it. It can’t possibly hurt us. It’s way too far away. Collowgullouric War, or Eta Carinae, it is a beautiful object to look at.
Move past this part of the sky and we’ve got some little clusters up there which are worth a look, but there’s plenty of objects to look at in this area, such as NGC 3532, which is yet another one of these small open clusters of baby stars.
But really, after you’ve enjoyed the beauty of the Jewel Box, maybe you don’t need to look for any more of these. As we go around towards the south-west, getting low, about 30 degrees or 1 outstretched hand and one fist above the south-western horizon.
We have the second brightest star, Canopus, which is the brightest in the constellation of Carina the keel. The star is called, as I mentioned, Canopus, or War, which is the crow. He is the brother of Sirius, or Warepil according to the Boorong.
This star is 310 light years away, 9 times the mass of the Sun, and 71 times its diameter, so it’s a very big, hot star. After War, or Canopus, turn back towards the west which is where we began our tour of this month of June and you should have noticed how much Sirus has dropped down.
In fact it may no longer be visible. It highlights how we take for granted that the Earth is always moving. We feel like we’re stationary, but no. We are moving as the Earth rotates on its axis. As the Earth zooms around the Sun once a year, as the Sun moves around the galaxy once every 250 million years, we are never standing still.
Special events for the month of June 2014. Lets start with the Moon. Friday the 6th will be the first quarter Moon at 6:39am. Lucky Friday the 13th, the Moon will be full at 2:11pm. Friday the 20th will be the last quarter at 4:39am.
And new Moon will occur on Friday the 27th at 6:08pm. The solstice occurs in the constellation of Taurus at 8:51pm on Saturday the 21st of June.
In the evening sky, for the first week of June, you’ll be able to see the planet Mercury very low in the north-west in the constellation of Gemini. The planet Jupiter is also low in the north-west in Gemini, but we’ll be able to see it most of the month.
On the first of June, the waxing crescent Moon will be very close by, and again on the 29th, but by the 29th, it will be pretty hard to see shortly after sunset.
Mars continues to fade after its opposition in mid-April. It’s high in the north-east in the constellation of Virgo. On June the 7th, the gibbous waxing Moon is above and to the left, but by the next day, it’s moved and to the right.
Saturn with its yellowing hues is in the constellation of Libra near the reasonably bright star of Zubenelgenubi. The gibbous Moon will slide past Saturn on the 10th and the 11th.
For those of you who like to get up early in the morning, the planet Mercury will reappear low in the north-east in the constellation of Taurus by the end of the month. But it’s rising at about 6am, only about an hour ahead of sunrise, so it’s going to be pretty tough to catch.
Venus continues to dazzle us in the morning sky, moving from the constellation of Aries towards Taurus in mid-month. It’s what we call minus 4.9 magnitude, which means very bright.
On the 24th, the crescent Moon will be above and to the left, and then by the 25th it will be below and on the right. One final thing to mention for June, but we can’t be terribly specific for this, you may remember I mentioned the constellation of Sagittarius in the podcast.
Round about now, we think, there is a cloud of gas called G2 which is several times the mass of the Earth which is getting perilously close to the 4 million solar-mass black hole at the heart of our galaxy.
Now, the black hole has been relatively quiet. It’s not doing a whole lot. The Swift spacecraft and any other astronomers and telescopes will be watching the centre of the Milky Way over this time to see if this gas cloud does interact with the black hole, and to see if anything does happen.
It’ll take several months for the information to reach the general public, but don’t forget – keep an eye on us via Facebook and Twitter for the most up-to-date details.
By the way, did you notice at the beginning of the podcast that I mentioned that imagination was the second most important thing? What is the most? Well to me, and people will argue this, I would say it’s mathematics.
Mathematics and imagination coupled, they give us the ability to look at the Universe in a rational way and try and understand some of the things that we see. Because this Universe is truly huge and at times very, very puzzling.
I hope you’ve enjoyed this tour of what’s visible in the southern sky for the month of June, 2014. I know it’s been a long trek but there’s so much up there to see. You can find our monthly sky guide podcast on iTunes.
If you want more detailed sky maps about sunrise and sunset, Moon and tide information, why not purchase a copy of our book, the ‘Australasian Sky Guide’ by Dr Nick Lomb, available from Sydney Observatory and the Powerhouse Museum shops, and our website.
It’s only 16.95 if you come into us. There is a little additional charge for postage and handling if you do it online. Our website is www.sydneyobservatory.com.au.
It has a galaxy of information about astronomy and visiting Sydney Observatory to see through our telescopes and to visit our 3D space theatre and our fabulous Sydney Planetarium.
We have programs available for all ages. You can also engage with us on Facebook and follow our tweets on Twitter @sydneyobs.
My name’s Geoffrey Wyatt. I hope you’ve enjoyed this guide, and we’ll see you again, soon.