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, Sydney Observatory’s Senior Astronomy Educator.
Geoff provides fascinating insights into the night sky as we see it now and as we have learned from it through history. Stars and constellations that feature this month include Sirius in Canis Major, Betelgeuse (sounds like ‘Beetlejuice’) in Orion, Aldebaran in Taurus, and Fomalhaut in Pisces Austrinus. Geoff will also help you to make sure you can tell the difference between Crux, or the Southern Cross, and a false cross in the sky.
Jupiter and Venus are planetary highlights this month, with a lovely photographic opportunity on 26 January just after sunset, with the 10% waxing crescent Moon appearing 7 degrees almost directly below Venus.
Listen to the audio, or read the transcript below for more details.
HEAR THE AUDIO
You can subscribe with iTunes or upload the 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 January 2012 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.
[scribd id=72302315 key=key-2ccel0ix07y229wwjg7f mode=list]
BUY THE BOOK
Our annual book, ‘The 2012 Australasian sky guide’, by Dr Nick Lomb has more information and star maps for months from December 2011 until December 2012 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 January 2012 monthly sky guide audio
Hello, I’m Geoffrey Wyatt, Senior Astronomy Educator here at Sydney Observatory and I’m going to be talking to you about what’s visible in the sky this month for January.
Of course, there are a few things that you need to help you with your sky tour. That is, of course, a printed map that you can download from www.sydneyobservatory.com. And of course, even better still, would be the book: ‘Australasian sky guide’ by Dr Nick Lomb.
Now, of course, at this time of year it’s lovely and warm so make time to go outside, sit on a rug, look up, and enjoy the sky. There are so many things up there even though we don’t get a terribly good view of the best part of the Milky Way at this time of year.
What I’d like you to do is to wait until it’s lovely and dark, go outside and find yourself as high a clear position as possible. Now, I appreciate you can’t all do this. Some of us live at the bottom of a hill like I do…. But if you can find a relatively clear view of the sky so you can Never Eat Soggy Weet Bix. I beg your pardon? So that you can see north, east, south, and west – our cardinal directions. And if you can find your way around, it’ll make things so much easier and more interesting for you.
We’re going to start off our tour of this month by looking towards the east. Fairly high up about 45 degrees. So, 45 degrees is going to be half way up as we look at it and it’s quite obvious what we’re going to start looking at: the brightest star in the night sky and that is Sirius, the Dog Star.
Now, of course, 45 degrees up is relatively easy. I think most of us could figure out half way up to 90 degrees. But actually, there are a few things that you can do to help find your way around. Yes, you do need to find your cardinal directions and quite often in astronomy, we call that the azimuth. So we can talk about an azimuth of 90 degrees being east, an azimuth of 180 degrees which is south, 270 degrees west, and zero, of course, north. So, we can talk about our direction from north in terms of degrees going from north to east. That will help us around the ground, but in terms of altitude, how high up…. well, degrees is what we use, but sometimes that can be difficult. However, if you hold your pinky at arm’s length, for most people, an outstretched pinky is about one degree or twice the size of the full Moon. Now, 45 degrees above the horizon, that’s 45 pinkies. That’ll take a while, but there are other things that you can do as well.
For most adults, the average sized adult, a clenched fist at arm’s length is about 10 degrees. If you spread your pinky to your thumb, so an open handspan, that’s about 15 degrees. Of course, if you’re a bigger fellow like I am, it’s more and if you’re smaller, it’s a little bit less, but on average, about 15 degrees.
So, start off, look due east, three handspans up, the brightest star in the night sky, Sirius, the Dog Star. Sirius is an intriguing star because it is the brightest star in the night sky, it’s relatively close and relatively big, but it’s actually a combination. You see, we have an unusual view of things. All stars look like twinkling pinpoints of light. They look like they’re the same distance away from us. They’re not. Stars are, of course, big hot balls of gas. Some of them are much bigger than others. Some of them are much closer than others.
Sirius is relatively close at 8.7 light years. That means you see it tonight as it really was 8.7 years ago. You see, you’re looking back into time. So, that’s relatively close. There are objects out there that we can see with the naked eye up to just on two million light years away, but that’s best seen from the Northern Hemisphere and that’s the Great Galaxy in Andromeda or M31. So, Sirius is close. It’s relatively big. It’s about twice the size of the Sun as well, so it’s a young, hot, bright star that’s nice and close.
Sirius is the brightest star in the constellation of Canis Major, the Big Dog. And Canis Major is relatively easy to see as a stick figure of a dog. If you look at a star map, you’ll see very elaborate drawings and, to be honest, you’ve no chances of seeing anything like that. The best way to see this constellation is to ask your three- or four-year-old to draw a stick figure of a dog. Then using Sirius as the chest of the dog, look for it rising in the east and hey presto, you’ll see a very simple dog figure. Sirius is also interesting because it has with it, a very, very small companion. And astronomers, look, to be honest, sometimes lack a little imagination, so they don’t have terribly fancy names for a lot of objects. Because this star sits right next to Sirius, it’s called Sirius B. And Sirius B is what we think will happen to the Sun in a couple of billion years from now when it dies. You see, Sirius B is a white dwarf. It’s nestled in the glare of Sirius itself, or Sirius A, and is almost impossible to see. However, until 2019, Sirius B is about as far away from Sirius A as it can possibly get.
So if you have a nice telescope (you won’t be able to do it with binoculars) you may just be able to split this tiny, tiny leftover ember of a dead star called a white dwarf, nestled in the glare of Sirius. And it’s well worth a look. It was discovered in the 1840s by Friedrich Bessel, who was looking at the gravitational wobble of Sirius.
Now, apparently some Indigenous Australian communities also looked at Sirius because its rising in the east at this time of year signalled to them that now is a good time to go and look for tasty, young dingo pups. Good for them. Not so good for the dingoes, I’m afraid. But that highlights an important use of stars.
You see, just about every culture on this planet looks at the stars for two reasons, well, three at a stretch: to work out the time of year, so to use them as a calendar, precisely what the Egyptians did in the past and what some Indigenous cultures of this land did in looking for dingo pups. And for navigation to find your way from place to place, which was very important if you were finding your way across deserts, or plains, or indeed, seas and oceans. But people also used the stars and the pictures that they would make up of constellations to educate and entertain one another. You see, depending on your age and your eyesight, you can see around two to three thousand stars from a very, very dark clear location. In the middle of the cities or larger towns, not so many. In fact, in one city that I like to go to and that is Tokyo, on occasion, I’m able to see one star. So, pollution does affect us somewhat horribly from this beautiful natural resource of the night sky.
But people would make up stories in the past about heroes and villains, battles and adventures, and they would use these to educate and entertain each other. Teach their children morals and all sorts of wonderful things. So the stars have been useful for us for many of thousands of years.
Once you’ve had a good look at Canis Major, the Large Dog and Sirius, oh, which of course shares its name with the ship, HMS Sirius which came to Australia as part of the First Fleet. And more recently sharing its name with one of the characters in the Harry Potter series of novels. Once you’ve had a look at that, I now want you to turn towards your left, ever so slightly, because we’re going to look for the rising constellation of Orion the Hunter in the north‑east. It’s relatively high up and it’s very close to Canis Major. As you would expect, Canis Major, the Big Dog, is one of the hunting dogs of Orion, the Hunter.
For most Australians, Kiwis, and South Africans… Look, it’s probably easy to say, can you see the saucepan? Now, the constellations have been named predominantly from the Northern Hemisphere. In fact, they’ve all been named from the Northern Hemisphere. But in the Southern Hemisphere, we see them the right way up. Well, those in the north would say that they see them the right way up and we see them upside down, but it’s all relative. As we look at Orion in the Southern Hemisphere, Kiwis, Australians, and South Africans don’t see Orion, the Hunter, as easily as they see a saucepan.
So, look for three stars in a lovely straight line, fairly close together. I want you to picture that those three stars make up the base of the saucepan. From one corner, you go up to the top of the saucepan, so it’s just a single star. Go back down along the base, up the other side where you’ll see three more star‑like objects that form the handle.
What you’re really looking at is the belt of Orion sitting very close to the celestial equator and the sword of Orion. If you have a decent pair of binoculars or indeed a small telescope, have a look at the middle star‑like object of the handle of the saucepan. And what you’re looking at there is a cloud of gas and dust, perhaps 20,000 times the size of our solar system and you are, in effect, looking into the maternity ward of stars because you are seeing baby stars being born at this very minute. It is one of the most beautiful sights in the night sky, but you do need a very good pair of binoculars or a small telescope.
The object, itself, is called M42, meaning it was the 42nd object in the catalog developed by Charles Messier, who created a list of red herrings. Things not to look at if you’re looking for a comet and this was the 42nd object. And it really is, at this time of year, perfectly placed and absolutely beautiful. M42, is also, of course, better known as the Orion Nebula. The word nebula is simply Latin for ‘cloud’ because as astronomers started to look through their telescopes, these things looked like clouds. And they are, of course, the birth and, later, the death of stars.
From the saucepan, the base of which sits on the celestial equator, drop down ever so slightly and you’ll see one of the few stars in the night sky to show any sort of identifiable colour. And what you’re looking at there is a star with a spectacular Arabic name, which has been mispronounced so long that we now call it Betelgeuse (pronounced ‘Beetlejuice’).
It was originally pronounced something along the lines of ‘Ibt al Jauzah’, meaning ‘shoulder of the giant’. Betelgeuse is a truly big star, but it’s right on the cusp of being a truly spectacular star as well. You see, it’s 600 light years away so it’s not exactly close. It’s 1,000 times the diameter of the Sun and several times more massive. How massive it is, however, there’s still a little bit of debate about that, but it’s on the limit. It may actually, at the end of its life, which is in its final stages now, catastrophically collapse and [pop] explode as a supernova. We don’t know if that is the case or whether or not it will simply become a red super giant, shed its outer layers, and die a graceful, beautiful death to form something called a planetary nebula and expose what’s the leftover former nuclear heart of a white dwarf, just like Sirius B that I mentioned at the start of the podcast. So, Betelgeuse is dying and the typical colour of a large, dying star is red. Don’t expect to see traffic light red. It is, in fact, more like a golden-orangey-pinky‑reddish. If you can see anything that’s bright and of those colours, you’ve found Betelgeuse.
As we leave Orion, the Hunter, who came to a fairly sticky end at the sting of the giant scorpion, Scorpius, we head towards the north but down a little bit to about 38, 40 degrees or so above the north by north‑east horizon. And there’s another slightly orange‑reddish looking star called Aldebaran, and this is the brightest star in the constellation of Taurus the Bull, which is perhaps the oldest of all the constellations. You see, constellations have been around for a very long time. In the second century A.D., Claudius Ptolemy created a catalog of constellations, about 48 of them, and we’ve been adding to it ever since.
Now, these constellations have come to us via ancient Arabic cultures. They’ve then gone from there to Greek cultures and then after the Renaissance, they’ve spread out and dominated our world view of the night sky. So, we’ve largely ignored cultures from other areas of the world, but Taurus is generally accepted to be one of the older of all the constellations because it’s a beast of burden in its barest form. But according to some mythology, it was, in fact, Jupiter, king of the gods in the form of a Bull, who was carrying a young maiden on his back to a nearby island. What a bizarre story. Anyway, Aldebaran looks as though it’s part of a V-shaped group of stars pointing back down towards the horizon. It’s between us and the rest of the stars in that V, which is actually a group of young stars called the Hyades, and that’s an open cluster.
Some people think it’s a really cool open cluster. I don’t because right next door, there’s an even better one and I’ll come back to that in just a moment. But if you can see the upside down V with the fairly bright orange‑reddish star at the end of the V, it’s the eye of the Bull. And then, of course, it has two very long horns. You see the longer the horns, the more fertile he was, according to mythology, pointing back down to the horizon on the north‑east towards the constellation of Gemini. But Gemini is just too low for us to see at the moment.
Once you’ve found that V shape and the bright star, Aldebaran, we then head around towards down north, ever so slightly, dropping down and you’ll see a remarkable group of stars. This group of stars is called M45, the Pleiades, the Seven Sisters, and there’s the rub. It’s very, very strange that so many people around the world refer to this group of stars as a group of sisters. They are, in fact, an example of an open cluster. This open cluster is a group of very young stars. They’ve been born from the same cloud of gas and dust at the same distance. They have the same chemical composition. Therefore, the only difference between the constituent stars is mass. Oh, and by the way, guess what factor is in fact the most important when looking at the life of a star? Yes, it’s mass. And as a result, open clusters like these are particularly favoured by astronomy examiners when setting exams for students. So, astronomy teachers love them. Astronomy students can almost guarantee that they’ll be in their exams.
This particular cluster is typically regarded as being one of the finest in the night sky. If you see a long exposure photo of it, the stars, and there’s quite a few of them there – though you can only see about seven to nine with the naked eye, seem to be embedded in a beautiful blue haze.
Well, this cloud that they’re embedded in, this nebulosity that we can see, is actually not related to them. Spectroscopic studies have revealed that the cloud is moving in the opposite direction to the stars and it just happens to be a happy coincidence that they’re in the same line of sight that we see.
Anyway, getting back to the story of the Seven Sisters. Why are they Seven Sisters? Why not, for example, Seven Hills of Rome or Seven Dolphins Swimming if you’re a Pacific Islander culture or something like that? But universally, they tend to be referred to as Seven Sisters.
Indeed, some Indigenous cultures of Australia refer to them as Seven Sisters where, one of the sisters has become lost. And it’s a fabulous story of the Woode Gooth-Tha Rra and the Minma-Birnee. This group of stars, the Pleiades is well worth a look at in a pair of binoculars, even if you have to borrow them from your next door neighbour.
Continue around from Taurus the Bull with its little cluster of stars, the Pleiades, we go past the very, very difficult constellation, Aries the Ram to see…You can really only see two to three bright stars in Aries. And remember Aries is the Ram that produced the Golden Fleece that Jason and the Argonauts spent so much time searching for.
We then pass Pisces, which is almost impossible to see especially getting down low in the north‑western sky, wrapped around the constellation of Pegasus. Once again, too low for us to really see. We continue around towards the west and the brightest star you’ll see, ever so slightly south of west at this time of year, about 30 degrees above the horizon and that is, of course, two handspans, is Fomalhaut. Fomalhaut is the brightest star in the constellation of Pisces Austrinus. It is the Southern Fish, not the constellation of Pisces, which is the zodiac constellation, but it’s just another fish. The star, Fomalhaut, represents the mouth of the fish and according to legend, it’s consuming the water that’s flowing from the jug carried by Aquarius, the Water Carrier.
Look, I can’t really see a fish here and you may not be able to either, but if you’ve your star map, you can see it’s an unusual looking shape. But to me, it looks like a paisley swirl. So, dig out one of dad’s or grandad’s ties and have a look for some paisley swirls and you may just be able to see Pisces Austrinus, the Southern Fish.
Right next door to it, there are two fairly bright stars in the constellation of Grus, the Crane. It looks like a bit of a cross and then from the midpoint of the cross, there are two trailing legs behind it. So what you are seeing is a crane with a lovely long neck, relatively short wings, I’d have to say, with a couple of feet trailing behind it in flight. Although, I’d say that one is rather difficult to see.
From Grus and Pisces Austrinus, head back up to about 58 degrees, so about 60 degrees – that’s four handspans, so we’re up a fair way. There’s only one relatively bright star there and that’s the star, Achernar. Achernar is the end of the line in more ways than one. You see, according to the classical mythologies from the north, it represents the end of the constellation of Eridanus, the River. But to some Indigenous culture in this beautiful land of ours, it represents one of two cooking stars for people who’ve not been too nice. They come to a fairly unsavory end, if you catch my meaning at the end of their life. You see, although we can’t see the beautiful glow of the Milky Way at this time of year, as long as there’s no light pollution, and there’s no Moon, fairly close to this bright star Alpha Eridani or Achernar, you may be able to see two glowing, fuzzy, hazy, milky blobs in the sky. Those two blobs are, of course, two of our nearby neighbouring galaxies. They’re not the closest galaxies to us. We can actually see those with the naked eye, but these two galaxies are very, very close at just 160 and 201 thousand light years, respectively. Named in honour of the first man to almost sail around the world and that is, of course, Ferdinand Magellan. So we call them the Large Magellanic Cloud and the Small Magellanic Cloud and they are completely separate galaxies from us. They’re moving towards us because our galaxy, the Milky Way, is the local bully on the block and is, in fact, cannibalising both of these two smaller galaxies.
These galaxies, according to some Indigenous cultures, represent some brothers who watch over people and take the bad people at the end of their life to Achernar and nearby Canopus, where they are, well, cooked and eaten. So, ew. Not a nice way to go.
However, the Clouds of Magellan, absolutely beautiful to look at, especially when you consider what they are. Galaxies at 160 and 201 thousand light years away.
We’re now almost facing the south, although we’re up fairly high. If you look down and try to find the Southern Cross…. oh, you don’t have much chance at this time of year. The Southern Cross will be lost in the glow of the horizon, more than likely behind a tree or your next door neighbour’s shed. So, you’re not going to see the Southern Cross at this time of year. Nor will you see the two bright Pointers that help you identify it as being the real Southern Cross. What you are likely to come across at this time of year, are one or two ‘false crosses’. Not really constellations, so we call them asterisms. Unfortunately, there are quite a few of them. The main one is actually an asterism made up of stars from two constellations, Vela of the Sails and Carina the Keel, as we head around towards the south‑east. It looks like a cross. It’s no wonder that people confuse it and think it is the real Southern Cross. But it’s bigger, it’s nowhere near as bright, and it doesn’t have the two bright Pointer stars. But this ‘false cross’ indicates a fairly typical problem and that is we love the Southern Cross of the Southern Hemisphere, but quite often, we’re not so good at identifying it or waiting until it’s in the right position for us to see. By the way, Vela and Carina used to be part of a much larger constellation called Argo Navis, the ship that carried Jason and the Argonauts in search of the Golden Fleece, which of course, relates back to Gemini, the Twins. Of course, they were on the ship, and Aries the Ram that produced the Golden Fleece. The constellation was too big and the International Astronomical Union met in 1930 and broke it up into four smaller constellations: Vela, Carina, Puppis, and Pyxis.
What you will see above the ‘false cross’ at about 60 degrees almost, above the horizon, is the second brightest star in the night sky. This star is called Canopus or Alpha Carinae. It is very, very bright and not far, really, from where we started off at Canis Major and its bright star, Sirius. So don’t get the two confused. Canopus, second brightest star in the night sky, inherently a far, far brighter star than Sirius, the Dog Star. It’s just that it’s so much further away. The other thing about Canopus is that it has a rather interesting little name and story that goes with it from our friends almost due north of here, and that is from Japan. You see, as sailors, fishermen in particular, would sail out looking for their stock of fish from Japan, as they came further south, they would see this very bright Canopus pop up above their horizon. Such a bright star makes you feel good. After all, we all love the brightness and the sparkle of diamonds, and this was like a diamond in the sky. So Canopus coming up over the southern horizon as fishermen would come south would make them happy and feel good. If you’re happy and feel well, the story goes that you’ll live a little longer. And the Japanese name, or the old Japanese name for this star is ‘Nagaiki’ meaning, ‘long life’. Obviously there’s a flaw to this logic for all of us living in the Southern Hemisphere that see it all the time, but it doesn’t matter. And each year there’s quite a few photographic competitions in Japan to photograph Nagaiki or Canopus as it becomes visible ever so briefly above their southern horizon. But to us, it’s pretty much there throughout summer and easy to see because it is so bright.
As we come back around towards the east, you will notice that Sirius, the Dog Star has risen a little bit higher than where we first started. We haven’t talked about terribly much that’s visible high overhead at this time of year now because there’s nothing terribly bright. All the action is around the horizon to within about 50 to 60 degrees. You see the best time to get the most stars in the beautiful Milky Way is in the middle of winter, which fortunately we’re still many months away from or very early in the morning at this time of year. One of the better parts of the Milky Way is now rising in the east, but we can’t see it overhead at the moment. You’ll have to wait several more hours before you can see the summer Milky Way.
Let’s have a look at the phases of the Moon for January 2012. First quarter moon will be on January 1st at 5.15pm. Of course that’s Australian Eastern Daylight Time or Daylight Saving Time. Full Moon will be on January 9th at 6.30pm. Last quarter on January 16th at 8.08pm. New Moon on January 23rd at 6.39pm. And first quarter, the second for the month, on January 31t at 3.10pm.
Now for a few of the events that we’re going to talk about in January we need to mention the relative brightness scale, if you like, or magnitude scale, based on the Pogson Ratio. This has been around for a long time. In fact, in its entirety, almost 2000 years going back to the time of the great astronomer Ptolemy. But the thing is, most scientists – well, all scientists, love to put numbers of values to things so we can say, ‘Hey, this one’s bigger than that one’, ‘This one’s more dense than that one’, or, in this particular case, ‘This one’s brighter than that one.’
So we’re going to use a scale which goes from, well it actually goes in the opposite way to what you might expect. So when we talk about small numbers, like 1 or 2, these objects are brighter than objects than objects that have a brightness of, say, 3, 4, 5 or whatever.
Now most people can see stars down to a magnitude of probably 5.5. As you get older, you don’t see as well.
The scale used to start at zero. But it’s now been extended into the negatives. So, throughout January, for example, Jupiter will get to minus 2.4 magnitude.
This is an apparent magnitude as you see it with the naked eye. So that’s very, very bright.
But Venus, on the other hand, gets down to minus 4.4. Now, 4.4, 2.4, it doesn’t seem that much difference. Unfortunately it’s not that simple. It’s actually a logarithmic scale. And then when we actually look at it, that difference of two magnitudes means that Venus is about six times brighter than Jupiter.
You don’t have to remember all of that sort of stuff. All you need to know is: large positive numbers: very, very dim. Remembering that you can only see down to probably about magnitude 5.5. Negative numbers: very, very bright.
The Sun (I forget the exact number) is about minus 27 or something like that. And, of course, you all know, DON’T LOOK AT THE SUN.
But Venus: minus 4.4: brightest object in the night sky after the Moon.
Some of the key highlights for the January nights: Throughout the month, the planet Jupiter will dominate the night sky, starting off in the constellation of Pisces, before moving across into Aries.
Jupiter is very conspicuous because of its astounding brightness. And for those that like the Pogson ratios or the brightness in magnitude, it’s minus 2.4. That’s as a result of it being relatively close, at just 750 million kilometers away. Look, you really can’t miss it. It’s the brightest object in the sky – apart from the Moon and Venus. Of course, we’re talking at night.
On January 2nd, just after sunset, which is at 8.10pm, look towards the north-north-west. About 40 degrees up, you’ll see a 60% gibbous waxing Moon. Gibbous means more than half, less than full. Waxing means it’s getting bigger.
Now it’s going to be in the constellation of Pisces the Fish. And Jupiter will be just 9 degrees above and to the right. Now on the next night, the Moon will have moved just enough so that Jupiter is above and to the left. This is a good opportunity for you to measure just how much the Moon moves from day to day. You’re simply going to use Jupiter as a signpost.
Now Venus is also very nicely placed for the month. As we know, Venus, Goddess of Love, starts off very low in the west just after sunset in the constellation of Capricornus, and then moves towards Aquarius by mid-month.
It’s setting by about 10.15pm due west and is very, very bright at minus 4.4 magnitude. That makes it about six times brighter than Jupiter. But don’t leave it until just before it sets because as we know anything close to the horizon is going to look dim because of the atmospheric pollution and interference with the light. So, shortly after sunset, wait till it’s dark, look west, and the very bright object is Venus.
Shortly after sunset on January 26th, the 10% waxing crescent Moon will be 7 degrees almost directly below Venus. And this is a very nice photographic opportunity. So, make sure you go out and have a look. And why not send your photos to us here at Sydney Observatory (geoffw@phm.gov.au). We might put them onto our blog.
Now you need to keep an eye on Venus as it moves towards its very important date with the Sun on 6th June. Yes, it’s still some months away – but this year, on 6th June will be the transit of Venus – when Venus moves in front of the Sun.
We’re going to talk about this pretty much every month because it is such a significant event. And if you miss it, you have to wait until December 2117. So, more than 100 years away. So, this is the last, if you like, cycle, that Venus has before this very important date.
At the moment throughout January, it’s about 36 degrees away from the Sun. And it can only ever move out to about 46 degrees which it will do by March, before swinging back for this important date on June 6th.
Special events for the mornings of January. We have the planet, Mercury, the fleet-footed god. Look, it may be visible early in the month, low in the east, just ahead of sunrise. I hope you notice I said ‘may’. It’s pretty hard to find. It’s not all that bright. And, again, for those of you who want a number – it’s at minus .37. But, look, it’s only 18 degrees ahead of the Sun, so it’s going to be hard to find. It’s going to be in the constellation of Ophiucus before moving into Sagittarius.
It is not all that bright but it is about the brightest object in that part of the sky. For a signpost, if you can find the constellation of Scorpius, look for the bright star in that, Antares, which is the reddish looking one. And drop down. You’ll find Mercury about 15 to 20 degrees below and just a tad to the right from Antares. It’ll be hard to find in the morning twilight – but well worth a peek. Good luck!
Now, Mars. Although Mars is rising quite late, at about 11pm throughout the month, you need to give it a few hours for it to get up high enough away from the horizon. So it’s effectively a morning object. Look, it’s disappointingly dim – but nonetheless it’s always something that people like to see. And it’s going to be in the area between the constellations of Virgo and Leo.
It’s always good to use a signpost to help find it as well because, as I’ve said, unfortunately it’s not very bright. The best chance for this will be on 14th January, when the waning gibbous Moon – so, we can see about 72% on this particular day – will be just 9 degrees above and to the left, as long as you’re looking towards the north-east.
Although dim, Mars is fairly conspicuous by its colour. Now, we say it’s the red planet – but don’t expect traffic-light red. It’s anywhere from rusty reddish to goldish to yellowish. Look, effectively anything that’s not blue or white in that particular area.
Also visible in the morning sky throughout January is the planet, Saturn. Now, it’s not very bright but it is well worth a look. It’s going to be in the constellation of Virgo all month. And on 17th January, look towards the east from about 3am onwards, and you’ll be able to see the waning crescent Moon – well, it’s just a smidge below half a Moon, at 47% – and the Moon will be about 5 degrees above and to the right of this beautiful ringed planet. Even if you have a small telescope or a good pair of binoculars, mount them onto a tripod, and have a look at Saturn. I’m sure you won’t be disappointed.
There’s just one other significant event for us in January and that is, of course, perihelion, which will occur on 5th January at 12 noon Daylight Saving time. This is our closest approach all year to the Sun. It is not the reason why we have seasons, of course, and it’s hot in the Southern Hemisphere. The seasons are determined by the tilt of the Earth. But on 5th January, we come closer to the Sun than we do at any other time of the year, at just 98% the average distance – which we call the Astronomical Unit.
So there you have the sky highlights for January 2012. Don’t forget you can download a printable map at our website – www.sydneyobservatory.com.au. Choose the ‘Astronomy’ tab at top right, and then select ‘Monthly sky guides’ from the left sidebar.
And of course for the complete picture of everything that’s in the sky, you need the 2012 version of the ‘Australasian sky guide’ by Dr Nick Lomb. It’s available online from Powerhouse Publishing, or from Sydney Observatory, Powerhouse Museum and of course major good bookstores.
I’m Geoffrey Wyatt, Senior Education Officer here at Sydney Observatory, and I hope you enjoyed the tour.
