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 (pictured at right).
Among Geoff’s recommendations for viewing in the southern sky this month are Fomalhaut, the brightest star in Piscis Austrinus (the Southern Fish), Achernar, the brightest star in Eridanus (the River), Orion (the Hunter) within which you can find the beautiful nebula, M42, and Aldebaran, the brightest star in Taurus (the Bull). He also tells you where to find the Large and Small Magellanic Clouds.
Geoff’s engaging presentation includes fascinating ancient Greek and even more ancient Indigenous astronomical mythologies. And don’t forget to look out for the Geminid meteor shower on 14th and 15th December. For this and more, listen to the December 2014 night sky guide audio, or read the transcript below.
HEAR THE AUDIO
You can subscribe with iTunes or upload the (42 mins 50 secs) audio to your iPod or mp3 player, or listen to it on your computer.
SEE THE SKY CHART
We provide an embedded sky map (below) and a starmapDec2014 (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 2015 Australasian sky guide’ by Dr Nick Lomb – this year the 25th edition of the book – has more information and star maps for months from December 2014 until December 2015 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 December 2014 monthly sky guide audio
Hello there, I’m Geoffrey Wyatt, Education Officer here at Sydney Observatory, part of the Museum of Applied Arts and Sciences.
I’m going to talk to you about what’s visible in the sky for the 10th month of the old Roman calendar, before the reform of Julius Caesar in 46 BC. Tenth month, December? Yes, that’s right, things were changed around a little bit and December became the 12th month, so we are on target.
This audio guide, transcript and printable sky map are available free from our website at www.sydneyobservatory.com.au/monthlyskyguides. We recommend that you use a printed sky map to help you navigate the night sky. You can to use the free, downloadable one from our website, or one from the observatory book, ‘The Australasian Sky Guide’ by Dr Nick Lomb. More details about that at the end of this podcast.
To have a look around the night sky, you’re going to need some resources. One of these will be the sky map, and a clear sky. To be honest, you can only get what you can get to. The higher you are, the clearer the view you have of the four cardinal directions, north, east, south and west, away from lights, away from trees and buildings, the better the view.
At this time of year it should be quite nice outside, so a nice comfortable blanket to sit on, and perhaps a drop of Chardonnay for those of us old enough to enjoy it. What we want you to do is wait until just after sunset, get a clear view, and I want you to look to a part of the sky that is 23 degrees right ascension, and 30 degrees declination.
Have you got it yet? This raises a problem. Most people don’t know what right ascension and declination are. They are the astronomer’s versions of longitude and latitude. It’s a pretty hard way of finding your way around as well, so we need some other way for you to find direction.
Most of us know our four cardinal directions. North, east, south, and west. With the Sun roughly setting over in the west, depending on the time of year, and roughly rising in the east, we can figure out north and south.
We can find our direction around from the north in something we call azimuth. 90 degrees east of north would be east. 180 degrees azimuth would be south. 270 degrees is west, and so on.
That path is relatively easy, but if I were to say to you something is directly overhead, I think most people could figure out that that’s 90 degrees up. Halfway would be 45 degrees. But when it comes to other angles, it is surprising how poorly we do at estimating them.
What I want you to do therefore is to hold out your hand at arm’s length. Clench your fist, but hold up your pinkie. For most people, regardless of your age and your size, because the proportions are all pretty much the same, your pinkie at arm’s length will cover roughly one degree of the sky or twice the size of the full moon.
Close the finger in so you’ve got a clenched fist, and you’ve got a marker for roughly 10 degrees. Outstretch your fingers and your thumb, and from pinkie-tip to thumb-tip you have 20 degrees.
Now we have an easy way of finding out directions. I want you to go to an azimuth of 270 degrees, so that’s west, and I want you to look about 60 degrees up from the western horizon. That’s three outstretched hand spans. What you’re going to look for is the fourth of the four Royal Stars.
People have been looking at stars for many thousands of years. Later on I’ll talk about some of the Indigenous stories, because I believe that the Indigenous people of Australia have been looking at the stars and passing their stores from one generation to the next longer than any other community. That’s something that we should all be proud of.
For the time being, we’re going to look for one of our four Royal Stars as was determined by the people living in Mesopotamia, that’s the region between the Tigris and the Euphrates Rivers, as many as 5,000 years ago.
You’re looking for a star that’s only 25 light years away, a light year. A light year is simply the distance that light travels in one year in the vacuum of space.
Light travels roughly 300,000 kilometres per second. Multiply that by 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, and 365.25 days per year, average, and you’ll end up with something like 9,500 billion kilometres which is such a silly number we just don’t use it. It’s too complicated.
We simply say, a light year is the distance that light travels in one year in the vacuum of space.
The star that we’re trying to find is 1.8 times the diameter of the Sun. It’s a young white star, in fact, one of the first stars to have had planets directly imaged around it in orbit. That was only done in 2008. This star is the brightest star in the constellation of Piscis Austrinus, the Southern Fish, and it’s called Fomalhaut.
The ancients that I mentioned a moment ago from Mesopotamia used stars like this as a form of calendrical marker. They used the stars Aldebaran in Taurus, Regulus in Leo, Antares in Scorpius and Fomalhaut, as we see it now, in Piscis Austrinus, to mark these key points.
But this was thousands of years ago and as seen from the North. Thousands of years ago but no longer, Fomalhaut was the brightest star near the Winter Solstice as seen from the Northern Hemisphere.
When you look at Fomalhaut, there are not many bright stars nearby. What I want you to try and see is an image of a fish, let your imagination go, particularly if you’ve had a glass of wine, and you may just be able to see a fish, or perhaps one of those fabulous paisley swirls that were so popular in the 1960s. If you can see anything that looks like a paisley swirl with a bright star, Fomalhaut, at the chunky end of the swirl, then you are looking at Piscis Austrinus, the Southern Fish.
It is, incidentally, drinking water flowing from the jug of Aquarius the Water Carrier, but goodness me, that’s very hard to see.
Now that you’ve seen Piscis Austrinus, just turn ever so slightly to your left, to the Southwest as we’re looking at it. You’re going to use your star map and try to look for a long necked bird with trailing legs in flight.
This particular group of stars is simply called Grus the Crane. It was created by Petrus Plancius, I don’t know if I’ve pronounced his name correctly, in the late 1500s. He was a fairly famous Dutch astronomer.
When you look at Piscis Austrinus and Grus the Crane, you’ll see straight away, these pictures look nothing like what you see in star atlases and on star maps. It’s very hard, they don’t look anything like those embellished diagrams. You’ve got to use your imagination to change those stick figures into more elaborate drawings.
Don’t give up, it’s well worth a try and when you eventually do see some of these constellations, it’s one of those, “Ah, I can see it,” moments.
40 degrees, or two hand spans to the left of where we are, and about 60 degrees above the horizon, so that’s three hand spans up, you should be able to see the ninth brightest star in the night sky and the brightest star in the constellation of Eridanus the River. The star is called Achernar.
Achernar is a rather intriguing star, because it’s about eight times the diameter of the Sun, but it spins 15 times faster. The effect of that rapid rotation is that the star flattens at the top and bulges in the middle. In fact, its equatorial diameter is about 50 percent greater than its polar diameter.
You’re looking at this star as it really was 144 years ago. You’re looking back into time. That means that this star is at a distance of 144 light years away.
Some Indigenous cultures of Australia use Achernar and the nearby bright star Canopus to represent the cooking fires of two celestial brothers. The brothers themselves are represented by the Large and Small Magellanic Clouds at a distance of 160,000 and 201,000 light years away, respectively. They are two of the closest galaxies to us.
Achernar is also intriguing because it’s on the opposite side of the celestial pole from the smallest of all 88 constellations, and some of us here in the South would argue the most important of all 88 constellations, which of course, is the Southern Cross. Unfortunately, at the moment, it’s not that easy to see unless you wait until about 3:00 AM, when it will be low in the south-east.
If you draw a line from the Southern Cross through the long axis going all the way across the sky towards Achernar, then go back halfway along that line, midway, that’s pretty close to the South Celestial Pole. It’s not dead accurate, but it’s close enough.
As we drop down from Achernar and head towards the second brightest star on the night sky, Canopus, we’re going to pass a couple of fairly important constellations. They’re really only important because this time of year, you can’t see the real Southern Cross and people get confused by what we call asterisms, patterns of stars that look like pictures that aren’t actually part of a constellation, or a constellation in their own right.
These asterisms we’re going to mention are the False Cross and the Diamond Cross, but they’re actually made up of stars from two separate constellations, Carina the Keel and Vela the Sails.
As we go past the false crosses, we’re going to look for the second brightest star in the night sky and that’s Canopus in the south-east. It’s about 50 degrees above the horizon, so that’s two hand spans and one clenched fist, in the south-east.
We have here a star that is 310 light years away, it’s 8.5 times the mass of the Sun. That’s a pretty big star. That means it’s actually about 1,300 times brighter. That makes it the brightest star within 700 light years of the Sun. Yet as we look at it, it’s only the second brightest star in the night sky. I wonder why?
Not only is the star’s intrinsic brightness important, but it must be its distance as well. There is another star that we’ll come to shortly which is not as bright naturally, but because it’s closer, it looks brighter.
Canopus is a fairly famous star. It was listed by the incredible astronomer Claudius Ptolemy in his Almagest around 150 AD. This whole region used to be part of a much bigger constellation called Argo the Ship that carried Jason and the Argonauts in search of the Golden Fleece. But over the years, astronomers actually thought it was too big, so they broke it up into four smaller constellations that we have now, Carina the Keel, Vela the Sails, Pyxis the Compass and Puppis the Deck.
Canopus is the brightest star in Carina the Keel. The name itself probably dates back to the time of the Trojan Wars, and according to the poems and the stories of the time, it was the name of the ship’s captain. Fair enough, we have the ship in the sky, why not have the captain as well.
What I like about this star is that the Boorong Indigenous community, a clan of the Wergaia language group in Northwestern Victoria, see this star as a male crow by the name of Wah. Wah was the first entity to bring fire to the people and he is a chief of the Nurrumbunguttias, the old spirits in the sky.
If you have a telescope or a small pair of binoculars, this part of the sky, although it’s a bit low, is actually a beautiful region to scan. Not too far away from the star Canopus or Wah, we have the intriguing object called Eta Carinae. There’s a cataclysmic variable star in a really bizarre object.
The historian Stanbridge actually recorded that the Indigenous people I’ve mentioned, the Boorong, referred to this star during its outburst in 1843. In the early 1800s, it went from a fairly inconspicuous third or fourth magnitude background star to being the second brightest star and then slowly fade away from visibility.
The Boorong actually incorporated this star’s variability into their Dreamtime or oral traditions, which is really quite amazing. As a result, this star became known as Collowgullouric Wah, which simply means the wife of the star Wah.
What we’re going to do after we’ve had a look at this region in the sky around Canopus is go towards the East and we’re looking to about 20 degrees above the Eastern horizon. What you should see is a twinkling, dazzling display of the brightest star in the night sky. It may not appear to be as bright as Canopus, which is higher up at this point in time, because being lower, it’s being obscured and it’s like being buffeted, if you like, by the atmosphere.
It’s a lot closer, at only 8.6 light years away, making it the fifth closest star to us. It’s also quite young, at roughly 200 to 300 million years. Its size? It’s a little bit bigger, nearly twice as big and nearly 25 times brighter.
There’s a few numbers there, but the main thing to remember is that it’s close, at 8.6 light years away. It’s nowhere near as bright as Canopus, but because it’s relatively bright and very close, it makes it the brightest star in the night sky seen from anywhere on the Earth, and it is Sirius the Dog Star.
It’s a beautiful object, and historically incredibly important. Thousands of years ago, the Egyptians used this star and they’d watch it very carefully. They’d see it disappear into the glare of the setting Sun and for about 70 days, it would be gone. They would then keep watch for it in the East in the early morning.
When they saw it pop up in the East, just ahead of the glare of the Sun, in something called heliacal rise, they were able to work out, on average, the length of the year to be 365 and a quarter days. Their error was just 11 minutes, and they did this thousands of years ago, which is truly an amazing achievement.
Sirius is beautiful, it’s also useful to work out the time of year. I should point out again that to the Boorong clans, it actually represents the star Warepil, and Warepil is a male eagle, and again, one of the chiefs of the Nurrumbunguttias, the old spirits.
To other Indigenous communities across Australia, the appearance of Sirius marked the time of the year when it was time to go looking for tasty young dingo pups. Not so good if you’re a young dingo pup, but a use of the stars nonetheless.
Let’s continue around towards our left or towards the north-east and just 20 degrees above the horizon. By the way, you may have noticed that we seem to be hugging fairly close to the horizon. I’ll explain a bit more about that later on.
Just 20 degrees above the horizon is a fairly bright orange-looking star. We call it a red super giant, but to most people, it’s not traffic light or laser red, it’s orangish. Anything that you see in this part of the sky that is not white or blue, and you’re probably looking at it. It’s the eighth brightest star in the night sky, 1,100 times the diameter of the Sun. Goodness gracious me, that’s a huge object.
Think about that for a moment. This little twinkling point of light that you’re looking at in the Northeast, 20 degrees up, is 1,100 times the diameter of the Sun. Don’t forget, the Sun is 114 times the diameter of the Earth. You’re looking at something which is enormously big.
Its distance? In the order of about 430 light years. It’s 100,000 times brighter than the Sun. It’s a dying star.
When you see a reddish looking star, it can be one of two things. It’s either an incredibly long lived, in fact, you could almost say, immortal star, or it’s a very short lived dying star as we see it. The thing is, the very small, almost immortal stars, well, none of those are visible to the naked eye. When you look around the night sky, every single star that you see that is orangish, reddish, is coming to the end of its life. It’s dying.
We’re not exactly sure of the mass of this star, but we know it’s fairly big. As a result, when it does die, it’s going to explode as a type two supernova. When? Next Tuesday at two o’clock. No, actually, we have no idea. It could be within the next million years or so. Who really knows? It would be really cool if it did explode during our lifetime, because it’s relatively close and would be spectacular to watch. However, let me assure you, it cannot possibly hurt us.
I haven’t told you its name yet, have I? This is one of the most unusual names in the night sky. A long, long time ago, its Arabic name was something like Ibt al Jauzah. Now, I might have that pronunciation incorrect, but that’s OK. Most of us have it incorrect, and its name has changed.
Its old name meant something like the Hand of the Big Man. It’s an unusual name and it’s difficult to pronounce. What happened is that over the years, its name has come to us from different Arabic communities in the Middle East. It’s gone to the ancient Egyptians, then to the Greeks, then of course, this rather unfortunate period called the Dark Ages, after which there was the Renaissance.
When people suddenly started to discover the translations of a copy of the translation of a copy, we had all these strange star names. As a result, many of them over the years have been mispronounced. You could perhaps say they have devolved. As a result, Ibt al Jauzah is now commonly called Betelgeuse.
Yes, I’m sure you’ve heard of it before. Some people call it ‘Betelgeeze’, ‘Betelguzz’, or even just ‘Betelgeeurse’. They’re all wrong. But they’ve become so common they’ve been accepted.
Now, as I’ve mentioned, it’s a dying star, and the brightest star in the constellation of Orion the Hunter. Australians tend to get the name of the constellation of Orion wrong, calling it the Saucepan, so that’s what we’re going to be looking for.
You should have a lovely clear view of it at the moment, looking towards the Northeast. Find the orange glow of Betelgeuse, then go a little bit higher and you’ll see three stars in a row, close together of equal brightness. They make up the base of the Saucepan. You can go up one side, go back up the other side, and then off at an angle for the handle, and there you have it.
The very famous constellation in the South as we call it, incorrectly, the Saucepan.
If you can find that, you’ve done well. I should point out that it’s not just Australians, in fact, our friends across the ditch in New Zealand often get it wrong as well, and so do many people in Southern Africa.
There are many different stories about Orion. You can just imagine that if I was to pass something onto you in secret, then to your friend, then to a relative and then have them pass it on and on and on, in a few hours, you’d probably get a different story. Imagine what’s going to happen over thousands of years.
There are many conflicting odd stories about some patterns in the night sky. But one of the ones I like is that Orion was a mighty hunter, in fact, the mightiest hunter ever to have lived. As a result, he used to hang around with the goddess of the hunt, her Greek name was Artemis.
But Orion made a mistake. He foolishly boasted that he could kill any animal on the planet. After all, he was a hunter. To teach him a lesson of humility, Artemis created the giant scorpion, Scorpius (not ‘Scorpio’ – that’s its astrological name. Scorpius is the correct astronomical name), to go into battle with him. The battle that followed was so incredible that it even caught the attention of Zeus himself, king of the gods.
Ultimately, Orion was stung and killed by the scorpion. Zeus took the scorpion and placed him into the sky. Artemis, with a tinge of regret, took the body of Orion and placed him into the sky also. But as a reminder to teach mere mortals to curb their ambitions, she placed him on the opposite side of the sky from Scorpius so that the two could never come together in battle again.
With Orion coming up in the East now, if you were to turn around a little bit too late, Scorpius has just disappeared from view over in the West.
It’s a fabulous constellation and at some stage or another, everyone has been able to have a look at it. The problem is that here in the Southern Hemisphere, it’s upside down. We tend to look for and know the Saucepan, not so much the mighty hunter, Orion.
Before I move on, I should point out that some have suggested that Orion was, well, how can I put it? A mighty hunter, but perhaps a little dim. You see, he’s standing on a rabbit called Lepus the Hare. How good a hunter can he be if he’s standing on a rabbit and chasing a flock of doves in the form of the Pleiades nearby? Not exactly big game, are they? Again, there are many different stories.
Go back to the Saucepan as I’ve described, and if you can, point your binoculars or your small telescope at the handle of the Saucepan, or in fact, the sword of the mighty hunter, Orion. If you can do that, I want you to narrow in onto the middle star-like object of the handle.
You could, perhaps, call this the maternity ward of stars, for what you’re looking at is the birthplace, is a truly amazing sight, even through a small telescope. Pair of binoculars, well, that’ll be pushing it. But if you can put them onto a tripod, you may just see that it is not a point of light.
What you’re looking at is the beautiful object named M42. Oh, great, what a fabulous name. Remember that astronomers don’t typically have wonderful imagination. It’s simply a catalog number. It simply means that it’s the 42nd object in the catalog developed by a man whose name began with M, Charles Messier, a Frenchman.
He made up a list of red herrings, things not to look at if you were trying to find a comet. This particular object was simply the 42nd object in his catalog.
It is a nebula. A nebula is simply the Latin word for cloud. It’s a star forming cloud that’s roughly 1,300 light years away. It’s absolutely huge, 24 light years across. It’s part of a much larger cloud that you can’t see all of unless you do incredibly difficult astrophotography. The whole cloud is called the Orion Molecular Gas cloud.
This cloud of gas and dust that we can see is being lit up from within by at least 6 baby stars and we call them the Trapezium. If you have a look, you might just be able to see a few of them in there. We believe that there’s enough material to form around 700 stars at the moment. Six of them, however, you can see relatively easily.
Leaving Orion, our next stop is a little bit further around towards the Northeast, and again, 25 degrees above the horizon. We’re looking for the star Aldebaran in the constellation of Taurus the Bull.
From here you’re going to see pretty much just another of these golden reddish stars. That tells us, as I mentioned before, the star is dying. But this is also the first of the four Royal Stars. Royal Stars? They were simply calendrical markers, the brighter stars next to a particular event in the sky.
Thousands of years ago, from Mesopotamia, Aldebaran in the constellation of Taurus was the brightest star next to the Vernal Equinox, and that is when the Sun crossed from the Southern Hemisphere into the Northern Hemisphere, crossing the celestial equator, marking the beginning of spring. It used to be the start of the year.
The idea of starting the year on the first of January, that was trialled a few thousand years ago at the time of Julius Caesar, but it fell out of fashion. It’s only in the last few hundred years, since the Gregorian reform, that it’s actually come back in to being the start of the year. For a long time, the year began in March.
Constellation Taurus, star Aldebaran, this is perhaps the oldest of all the 88 constellations that we now officially recognise. It’s a very important creature. A bull is not only a food source for many of us, it’s a beast of burden. It’s not surprising that this animal worked its way into sky lore.
Let me warn you, however, you should never actually approach Taurus the Bull, because in one of the stories, it’s actually the king of the gods, Zeus or Jupiter, carrying his lover, the beautiful young girl Europa, off to the island of Crete. This was such a famous story from long ago that the entire continent of Europe took her name.
Aldebaran the star is what we call a K5 orange giant. It’s the 13th brightest star in the night sky. It’s at a distance of about 65 light years away and it’s coming to the end of its life. At the moment, it’s exhausted most of its hydrogen fuel in its core and is expanded and expanded and expanded is now 44 times the size of the Sun, but only a little under twice its mass.
If you scan the area around Aldebaran, it looks like it’s part of a group of stars that form a large V. Well, it’s not. It’s actually between us and that V shape group of stars called the Hyades. The Hyades is an open cluster, which means it’s a group of fairly young stars, they’re quite young, probably no more than 600 million years old. They’re about 153 light years away.
They’re all, if you like, siblings, made at the same time from the same gas cloud, so they have the same chemical composition. The only variable is mass.
Aldebaran sits between us and that group. With the two dimensional view of the sky that we have, they look like they’re associated, but they’re not.
Go a little bit further towards the North and we’re still only 25 degrees above the horizon. You’re going to see a group of young stars, yet another open cluster. But I think this one, most people would agree, is the most spectacular of all. It’s call M45. Yes, it’s another one of those red herrings not to look at if you’re looking for a comet.
But it has another name, the Pleiades. To some Indigenous communities, for example from the Maralinga area of South Australia, they have a story that relates to this group of stars. It’s one of my favorites. That’s the story of the Woode Gooth-Tha Rra and the Minma-Birnee.
The Pleiades or the Woode Gooth-Tha Rra and Minma-Birnee are about 445 light years away. They’re not exactly close, but they’re very young, less than 150 million years old. They’re so cute. They’re just baby stars that have just formed. In human terms, I suppose it’s a little bit like going to visit them in the maternity ward at the hospital.
When you look at pictures of M45 or the Pleiades online, you’ll actually notice that quite often it’s surrounded by a lovely bluish glow. That bluish dust cloud as it turns out is not part of the Pleiades itself. It’s between us and those stars. Again, the two-dimensional view that we have is a little confusing at times.
To most people around the world, the Pleiades are known as the Seven Sisters. What’s intriguing is that this idea of the seven sisters seems to repeat itself around the world. There are many different cultural stories that relate to them as being seven sisters including the one I’ve mentioned of the Woode Gooth-Tha Rra and the Minma-Birnee.
If you look at them, however, you’ll probably be able to see six. If you’ve got really good eyesight, you might see nine. Rarely do you ever meet anyone who can say, “Well, do you know what? I can see seven.” Strangely, they’re called the Seven Sisters.
By the way, if you drive a Japanese car and it has an emblem on the bonnet of a group of stars joint together by lines, you’re looking at a Subaru. Yes, that’s the Japanese name for this group of stars, Subaru.
To the ancient Greek, they represent the daughters of Atlas who carried the world upon his shoulders, his wife, Pleione, and their seven daughters. It’s well worth having a good look at.
The Pleiades used to be their own constellation, but for some time now, we consider them to be part of the larger Taurus the Bull. Continue now towards the north and look for another zodiac constellation with an enormous number of stars.
Let’s count them together. In terms of bright stars, we have one, two, three, and that’s it. It’s fairly devoid of stars. What can you make out of a group of three stars? It’s the horns of Aries the Goat.
Aries is the goat that produced the Golden Fleece that’s so famous in the story of ‘Jason and Argonauts’. There’s not a whole lot to see here unfortunately, but it is a very famous constellation in terms of sky lore and astronomy.
Our version of celestial longitude starts in this part of the sky and we call it the first point in Aries. Sadly, it gets rather complicated here because the Earth does a 26,000 wobble on its axis and everything changes position ever so slowly.
This first point of Aries is no longer in Aries but is now moved over into the next constellation, Pisces, the Fish, and heading towards the constellation of Aquarius.
If I could sing, I would burst into song “The Dawning of the Age of Aquarius.” But trust me, you can listen to me on a podcast but no one can listen to me sing.
The point is that this celestial starting point, the first point of Aries, was long ago in Aries. No longer; it’s moved over to Pisces and heading towards Aquarius. It is simply the point in the sky where the celestial equator crosses with the ecliptic.
In my opinion, don’t waste too much time looking into Aries with only three bright stars. Continue past it and look towards the northwest for a group of stars that makes up a square. What you’re looking for is the flying horse, Pegasus.
If you’re away from the city lights and there’s no Moon and you have a good view towards the northwest, because it is quite low, you should be able to see the body of the horse, which of course is the big square. Look carefully at one of our star maps and you should be able to pick out the long neck and the face of the horse.
It’s got two cute little front legs, but sadly for a flying horse, what’s missing? The wings. I can’t ever see it with rear legs either.
The main reason in spending time trying to find the square Pegasus is that wrapped around it is a fairly faint dot to dot V-shape with a little bit of a loop at either end. Oh, goodness, that sounds a bit complicated and you will definitely need your star map to be able to see this.
The V-shape with the loop at either end represents Aphrodite and her son Eros, or if you like, Venus and Cupid. It is the constellation of Pisces, the Fish.
Continue past Pisces and we’re going to finish off as we look towards the west for the constellation of Capricornus, the Sea Goat. It’s just below Fomalhaut and very hard to see. It is the second faintest of the constellations. It’s probably a bit late for that.
I mentioned earlier that we’ve done a bit of a loop around the horizon, between no more than 30 and 50 degrees up. We haven’t looked directly overhead. Why not? Because at this time of year, all the interesting stuff hangs around the edge, if you like. The periphery of Via Lactea, the Milky Way, the brightest part that we see of our galaxy, is around the horizon.
The stuff that’s directly overhead, such as Phoenix the Bird, which is one of the 12 constellations invented by Petrus Plancius in the 16th century, or Cetus the Sea Monster or some of the newer ones like Sculptor were introduced by Nicolas Louis de Lacaille in the 18th century. I’ve probably made a mess of his name, but that’s the best I can do.
These constellations are in effect astronomical fillers. There’s not a whole lot up there to have a look at with the naked eye. So they’re there as a way of breaking the sky up into more manageable regions, a bit like suburbs in the city. They are just constellations.
Again, all the action that we’ve just been talking about is that band that’s somewhere around 50 degrees and below right around the horizon.
If you can get away from the bright glow of the cities or the towns and there’s no Moon in the sky, head back towards the south and you should be able to see the Large Cloud of Magellan and the Small Cloud of Magellan. These look like two fluffy bits of Milky Way that have drifted off and broken away, a faint, wispy glow of light.
The Large Magellanic Cloud is an irregular galaxy with a central bar. It’s the third closest galaxy to us and about a hundredth of the size of the Milky Way. There’s enough material in this galaxy to form about 10 billion stars the same as the Sun. At 160,000 light years away, astronomically, it’s very, very close.
In fact, so close, that Milky Way is the local bully of the area is stripping stars away from the Large Magellanic Cloud in something called the Magellanic Stream.
If you’ve got a pair of binoculars or a small telescope, the Large Magellanic Cloud is actually a rather spectacular object to have a look at. You’ll be able to see one of the largest nebulae that we’ve ever seen, called the Tarantula Nebula. Once again, “nebula” is just Latin for cloud. It’s a very rich star forming region and well worth a look.
Long, long ago, last century even, in 1987 – goodness me, such a long time ago – this area of the sky was home to the first supernova visible to the naked eye since 1604. We’re desperate to see another star blow up in our galaxy. Well, not too close, of course. Because we haven’t seen one for such a long time.
The other small patch of lot that you can see is the Small Magellanic Cloud. It has a mass of about seven billion times that of the Sun and is about 201,000 light years away. To some Indigenous communities in Central Australia, these two galaxies represent brothers who lived in the sky.
Key events for December 2014. The full Moon will be on Saturday the 6th, at 11:27 PM. Last quarter, it was on Sunday, the 14th, at 11:51 PM. The new Moon will occur on the solstice on Monday, the 22nd, at 12:36 PM. First quarter Moon will be on Monday, the 29th, at 5:31 AM.
The solstice, the point at which the Sun reaches its most southerly point in the sky, is at 10:03 AM, on Monday, the 22nd of December. Perhaps our best opportunity to see meteors for the year, with the Geminid meteor shower, occurs on the mornings of the 14th and 15th.
Early in the morning, look towards the constellation of Gemini. There will be a quarter Moon, but this may not have a great impact. If we’re lucky, you should be able to see lots of short, sharp streaks of light as particles of dust burn up in our atmosphere and make it glow. You do need to be away from the city lights to get the best view, however.
In the evening sky, shortly after sunset, you’ll be able to see the planets Venus and Mars low in the west. On December 23rd, the thin crescent Moon is below and to the right or west of the planet Venus. On Christmas Day, the 25th, the crescent Moon is below and to the right or north of Mars.
For the early risers, Jupiter is high in the constellation of Leo the Lion. On the 12th of December, the gibbous Moon is above and to the left or west of Jupiter. Saturn, perhaps the most beautiful object you can ever see through a telescope, becomes visible low in the east by around mid-month. On the 20th of December, the crescent Moon is to the left or north of Saturn.
If you want more detailed sky maps – sunrise, sunset, Moon, and tide times and a whole lot more astronomical information – we highly recommend you buy the book ‘The Australasian Sky Guide’ by Dr Nick Lomb available from Sydney Observatory and Powerhouse Museum shops.
It’s only $16.95 if you come into our shops. There are additional postage charges if you order online. Our website at www.sydneyobservatory.com.au has a galaxy of information about astronomy and visiting Sydney Observatory to use our telescopes, see a program in our 3D space theatre or visit the Sydney Planetarium.
We have programs for all ages. You can also engage with us on Facebook, SydneyObservatory, all in one word and Twitter @SydneyObs.
My name is Geoffrey Wyatt. I’m the education officer here at Sydney Observatory. This will be my last podcast in this position. I hope you’ve enjoyed the tour of the December night sky.
