To help you learn about the southern night sky, Sydney Observatory provides a guide and a sky map each month. This month’s guide is presented by Dr Andrew Jacob, Sydney Observatory’s Curator of Astronomy.
This month, learn how to find the summer constellations of Orion, Canis Major and Taurus. Tour the Milky Way galaxy from the Southern Cross to Auriga in the north and discover the brightest stars in the sky. Andrew also tells us how to find the planets Mars, Jupiter and Saturn in the morning sky with the help of the Moon. And what are the celestial highlights to look out for during the year of 2020.
See the Sky Chart
We provide a StarMap 01 January 2020 (PDF) which shows the stars, constellations and planets visible in the night sky from anywhere in Australia. To view PDF star charts you will need to download and install Adobe Acrobat Reader if it’s not on your computer already.
Read the Guide
Hello, and welcome to the night sky for January.
This is Andrew Jacob, and I’m the Curator at Sydney Observatory, part of Sydney’s Museum of Applied Arts & Sciences. Come on a tour of the night sky with me. Learn what stars and constellations are visible, where to find the planets and what special events are happening overhead this month.
To make the most of this guide, you should begin by gathering a few items together. Firstly, you will need a star map. You can download a free one from Sydney Observatory’s website where you’ll find it in the Astronomy Resources section under Monthly Sky Guides. The star map will show you what stars and constellations are visible in the night sky this month and I’ll be referring to that star map in this guide.
As well as the star map, a torch with a red LED, or one covered with a few layers of red cellophane, will be very useful. The red light will allow your eyes to remain dark adapted during the evening, yet still allow you to read your star map.
Finally, a pair of binoculars or a telescope can be very handy. They’re not essential for following this guide but if you do have them they will help you see a few of the fainter objects more easily and in more detail.
Now that we have our equipment together we need to know a few directions and also how to measure angles across the sky.
You can find the cardinal directions – North, South, East and West – from a compass app on your mobile device, or just remember, of course, that the Sun rises in the east and sets in the west. And if the Sun is setting at your right shoulder, then you must be facing south. Another useful direction to remember is the zenith. This is the point directly overhead.
To find your way around the night sky, it helps to know how to measure angles across it. It makes no sense to say, for instance, that one star is “2 centimetres” to the left of another or that a shooting star left a trail “half a meter” long! Instead we should use angular measurements. The distance around the horizon, from North, through East, South, West and back to North is 360 degrees. And from the horizon vertically upwards to the zenith overhead is 90 degrees.
But how do we measure smaller angles? Well, despite the great variety of human form our fingers, hands and arms are all pretty much in the same proportions. If you hold your hand out at arm’s length and stretch out your little finger and thumb to make a hand span, they span an angle across the sky of about 20 degrees. A fist held out at arm’s length makes an angle across the sky of about 10 degrees. And a finger held up at arm’s length is about 1 degree, or twice the width of the Moon or the Sun. I’ll be using these measurements during this guide. So, a hand span at arm’s length is 20 degrees, a fist is about 10 degrees, and a single finger is about one degree across the sky.
One final point to note before we get started. The Earth rotates and so the sky changes hour by hour. My descriptions of the constellations and stars in this guide fit the time of one to two hours after sunset.
This month the best constellations and stars are high overhead. So let’s begin by getting comfortable – grab a blanket, lie down with your feet facing West and look straight up towards the zenith. With your feet pointing westwards most of the constellations above will appear upright, rather than upside down as they often do from the southern hemisphere!
At this point, if you are at a dark site away from city or town light pollution and if the Moon is not up, I recommend you wait for about 15-minutes for your eyes to adjust to the darkness. Your view of the night sky will be much better if you do this.
If you are in a dark location, and there is no Moon up, you will see the Milky Way, the edge-on view of our own galaxy, stretching from the south horizon on your left, passing overhead through or close to the zenith, and reaching the north horizon on your right. It appears as a milky irregular band of light. If the Moon is up or you are near a city or large town and light pollution affects your view, the Milky Way won’t be visible but you will still see a band of bright stars stretching across this part of the sky, from south to north.
We begin with the constellation Orion, the Hunter in the sky, slightly north or right of the zenith. With the help of your star map locate the three stars of Orion’s belt. From top to bottom these are Alnitak, Alnilam and Mintaka. To the right is the star Betelgeuse, glowing orange-red or maybe yellow-orange. This star represents Orion’s shoulder. It is a red-giant star coming to the end of its life, it is 425 light years away and it’s hundreds of times larger than our Sun.
To the left of Orion’s belt is the bright star Rigel, one of Orion’s knees. Rigel is also at a late stage in its life cycle, although not as late as Betelgeuse. It is about 1000 light years away and its surface temperature is about 11,000 degrees Celsius – about twice as hot as our Sun.
Now, if Betelgeuse and Rigel form Orion’s right shoulder and left knee respectively you should now be able to imagine the figure of a man, perhaps with the help of your star map. His head and shoulders are to the right, his body narrows to the three “belt stars” at his waist and his legs stretch out to the left. From Betelgeuse to Rigel is about a hand span or about 20-degrees across the sky. Between Orion’s legs, hanging from his belt, is Orion’s sword. To your eye this appears as a line of three fuzzy stars. Through binoculars they appear as three groups of stars, with the middle one surrounded by a faint hazy “cloud”. This cloud, or nebula, is the Orion Nebula, over 1500 light years away. It is also known to astronomers as “M42”. It is perhaps the most photographed object beyond our solar system and is a large cloud of, mostly, hydrogen gas which is producing new stars. The cloud is 15 light years in diameter and the stars you see embedded within it (with your binoculars) were formed from the collapsing hydrogen gas within the last million years or so.
A moment ago I mentioned “light years”. What is a light year? It’s a measure of distance, even if it sounds like a time. If you have a torch shine its light into the sky for a moment. The light from your torch travels incredibly fast. In just one second it goes almost 300,000 kilometers. That’s seven and a half times around the Earth or almost the distance to the Moon. In fact in just one and a quarter seconds your torch light would reach the Moon, 380,000 kilometres away. In eight and a half minutes the light would reach the Sun, 150 million kilometres from Earth. After five hours light from your torch would pass Pluto. Finally, after one year of time your torch light will have travelled one light-year of distance. Yet we still haven’t reached the next nearest star!
Proxima Centauri, our closest star after the Sun, is about 42 million million kilometres away from us. Your torch light would take about 4.2 years to reach it. So we can say that Proxima Centauri is about 4.2 light years away from Earth. This also means that we see Proxima Centauri, the star, as it was about 4.2 years ago. We are looking into the past to see everything in the universe.
So a light year is simply a distance, and one light year is about 10 million million kilometers long.
Let’s return to Orion. Orion is a pivotal constellation – its stars are guides pointing to many other interesting stars, constellations and other objects.
If we extend the line of Orion’s belt stars down and right we come to an orange star amongst a V-shaped pattern of fainter stars. From the belt to this orange star is about 20-degrees or a hand span. This group of stars is Taurus the Bull. The orange star is Aldebaran, the eye of the Bull, and his head is the V-shape. A little further down and to the right, still following the line of Orion’s belt stars is a small cluster of sparkling diamond-like stars. Best seen through binoculars, not a telescope, these are also known as the Pleiades or Seven Sisters. It’s a group of young stars all born from the same nebula – so they really are sister stars. These represent the daughters of Atlas, who holds the sky aloft on his shoulders, and Pleione.
Returning to Orion’s belt we now follow the line of the belt up and to the left, again about 20-degrees. Soon we reach the brightest star in the sky, Sirius, high overhead. Its name means “scorching” or “brilliant” and you can see why. Sirius is also called the “Dog Star” because it’s the brightest star in the constellation of Canis Major, the Big Dog. With the help of your star map you can identify the shape of the dog, the faithful hunting companion of Orion. Just above Orion, as we lie here, and back towards the eastern horizon 30-degrees from Orion’s belt, is the bright star Procyon in the constellation Canis Minor, the Little Dog. This constellation looks nothing like its name at all – only a few of the 88 constellations in the sky do look like their name.
Returning again to Orion, we now use his sword to direct us to our next destination. You might notice Orion’s sword points directly left (South) and right (North). This is a very useful thing to remember when the Southern Cross is low in the sky as it is this month – it’s a summer compass if you like. Following the direction of the sword far to the North, to the right, brings us to the bright yellowish star Capella, 50-degrees away and just a fist width above the northern horizon. Capella is the brightest star in the constellation Auriga, the Charioteer who was a legendary king of Athens.
Following Orion’s sword to the South, or left, again about 50-degrees brings us to a bright, white star. This is Canopus, 205 light years away and the second brightest star in the night sky after Sirius. Canopus is one of the celestial navigation stars used by ships navigators for centuries. Appropriately it’s the brightest star in the constellation Carina, the Keel of the great ship in the sky. The ship was once a single constellation called Argo Navis. But in 1930 it was broken up into the keel and the nearby sails, Vela, the rear deck, Puppis, and the ship’s compass, Pyxis. This is not an easy ship to identify in the sky – perhaps it’s fading into a summery ocean haze?
More easily identified is the False Cross. This is an “asterism” or star-shape not one of the 88 formal constellations. It lies on the border of Carina and Vela taking in stars from both constellations. It is larger and fainter than the real Southern Cross which lies further to the left and very close to the southern horizon.
Let’s look back to Canopus. Below this star you will notice, if you are in a dark site away from city lights and with no Moon in the sky, two cloudy patches. These are the Large Magellanic Cloud (LMC on your map) and Small Magellanic Cloud (SMC on your map). These clouds are companion galaxies to our own Milky Way galaxy. But our galaxy is bullying and harassing these smaller companions and tearing them apart. We used to think that in the distant future the Milky Way would absorb both these small galaxies but some recent work suggests they are just passing by.
The Small Magellanic Cloud is the lower of the two, that is if you are still lying down with your feet to the west. Just to its right, about 15-degrees away, is another bright star. This is Achernar, meaning the River’s end. It is the star at the end of the constellation Eridanus, the River in the sky.? Now here’s a small challenge for you – can you trace the river Eridanus across the sky? It meanders from Achernar across the zenith to its source near the star Rigel in Orion. Use your star map to “star hop” from one star to the next along the course of the river, travelling upstream to Orion. This “star-hopping” technique is a good one to practice for future use when trying to find faint or obscure celestial objects, particularly with your binoculars or a telescope.
Let’s review what we’ve seen tonight. We begin from the South, on your left, and we’ll travel along the Milky Way. Close to the southern horizon is the Southern Cross, with the Two Pointer Stars below. Moving northwards, to the right, we pass the False Cross between Vela the Sails and Carina the Keel. Then comes Canopus, the bright navigation star, and below it the Magellanic Clouds and Achernar. Next along is Canis Major and the brightest star, Sirius, followed by Orion the Hunter with his belt and sword. Then comes Taurus the Bull and the Seven Sisters and finally low down on the northern horizon is Capella in the constellation Auriga. Phew! What a superb summer sight!
It’s an even better sight with binoculars. If you slowly sweep the Milky Way passing all the objects I’ve mentioned tonight you’ll also discover, in between, hazy gaseous nebulae where stars are born, sparkling clusters of young stars and curious star patterns here and there. At first it seems overwhelming but if taken in bite sized chunks, month by month, there’s a lifetime of observing to be had.
But wait there’s more! Most of the brightest stars in the night sky are visible during January nights. Sirius, the Dog Star is the brightest followed by Canopus, the navigation star. Third brightest is Alpha Centauri, one of the Two Pointers low in the south. Next are Arcturus and Vega, neither visible on January evenings. Sixth brightest is Capella, a fist-width above the northern horizon, and then Rigel, Orion’s knee. Next is Procyon in the Little Dog. Ninth is Achernar at the end of the River Eridanus. Finally, Betelgeuse, Orion’s shoulder, is the tenth brightest star in the night sky (unless it fades as it has been doing recently!). That’s eight of the ten brightest stars all visible at once on these warm summer evenings – January is truly one of the best months to be outdoors journeying through the starry realms!
And now, let’s have a look at the special events and highlights for this month.
What are the special events and highlights for January 2020?
Let me note that all the times I am about to mention are in Eastern Australian Daylight-saving Time or AEDT, as it is properly known. Please make the appropriate adjustments for your time zone and state if necessary.
Let’s start with the Moon phases. We begin the month with a First Quarter Moon on Friday 3rd?at 3:45pm, Full Moon occurs on Saturday 11th?at 6:21am, Last Quarter is on Friday 17th?at 11:58pm and finally New Moon is on Saturday 25th?at 8:42am.
The Moon is the brightest object in the night sky no matter what phase it is in. It is well worth observing its changing phases or looking closely at the craters, plains and other features with binoculars or a telescope. But to get the best views of the Milky Way and the constellations it is best to avoid moon-lit hours. If the Moon is between New and Full (i.e. waxing or getting bigger) wait for it to set before observing the Milky Way and stars. If the Moon is between Full and New (waning or getting smaller) observe before it rises. You don’t need a daily list of rise and set times – just watch the Moon for a few days and you will soon learn to predict its behaviour.
So in Jan 2020, until the first weekend enjoy views of the Milky Way after midnight; then observe the Moon for the next week (until about the 12th); for the next two weeks enjoy the dark skies and views of the Milky Way stretching across the sky; and from the 25th?to the end of the month watch the Moon growing in phase and wait for it to set before looking for the Milky Way and fainter objects.
What planets are visible in January 2020?
Venus is the only evening planet this month, and in fact it’s the “Evening Star”. It remains prominent above the western horizon all month moving through the constellation of Capricornus into Aquarius during the month. On January 28th?the crescent Moon joins Venus for a striking pairing in the western sky.
In the morning sky it’s Mars, Jupiter and Saturn this month.
Mars rises around 2am during the month and remains in the eastern sky until sunrise. On the 21st?a waning crescent Moon passes by just below and left of Mars, helping you to identify the red planet from other bright stars nearby.
Both Jupiter and Saturn will be seen in the south-east during the morning twilight. Jupiter rises just before the Sun all month but may be difficult to spot until after the first weekend. Saturn wont be seen until after the middle of the month when it begins rising shortly before sunrise. On the 23rd?a crescent Moon appears close to Jupiter.
What other events are happening in January?
Earth reaches its closest point to the Sun, or perihelion, on Sunday January 5th?at 6:48pm. We will be just over 147 million kilometers from the Sun, just a little closer than our average of 149.5 million kilometers.
On the 11th?there is a penumbral lunar eclipse. And this, I think, is my observing challenge for this month!? Earth’s shadow has two parts – a dark circular umbral shadow surrounded by a fainter penumbral “doughnut”. In a total lunar eclipse the Moon passes through the dark inner umbra and darkens and turns red. However, in this penumbral lunar eclipse the Moon only passes through the fainter outer “doughnut” and won’t darken appreciably. And that’s the challenge: can you detect the dimming of the Moon’s surface?
Look to the west from about 3 to 3:30am (AEDT) on Saturday 11th?January. Take note of how bright the Moon appears. Just after 4am the Moon begins to dip into the penumbral shadow. As the Moon descends towards the horizon it should darken, and this will be most noticeable on its left-hand side where the, usually bright, white lunar highlands lie. Just to make it extra challenging twilight brightens the sky from about 5am and the Moon then sets just as the Sun rises at about 6am. So I suspect that if you haven’t detected the dimming of the Moon in the penumbral shadow by just after 5am it will probably be too late. In any case, Good Luck!
On the 23rd?there is a day-time occultation of Jupiter by the Moon. In this event the Moon moves in front of Jupiter and hides, or occults, it. You will need at least binoculars, maybe a small telescope, to see this well and even then it will be a challenging observation. We’ll post more detailed information about this closer to the time on Sydney Observatory’s blog pages.
Having just celebrated the 50th?anniversary of the first manned lunar landing I should note that it is Buzz Aldrin’s 90th?birthday on January 20th. Happy Birthday Buzz!
It’s January so let’s have a look ahead at special events for the rest of the year.
There will be a partial solar eclipse on 21 June but visible only from the Darwin region and the tip of Cape York.
A Blue Moon occurs in November for most of Australia, but in October for Western Australia.
Supermoons occur in March and April. The arbitrary nature of the Supermoon definition means some sources also include February and May. Whatever! April has the super-duperest Moon for the year.
The Geminids meteor shower is shaping up to be good this year. With no Moon up these bright, and sometimes long-lasting meteors should finally be worth staying up all night for in early December.
SpaceX will be launching more of its Starlink satellites – the ones that are worrying astronomers (both amateur and professional) worldwide for interfering with astronomical observations. And a flotilla of spacecraft will launch for Mars. The USA, a European-Russian collaboration, China and the United Arab Emirates will all send spacecraft to the red planet in 2020.
*The Japanese spacecraft Hyabusa 2 which took a sample of the Ryugu asteroid last year will return its sample to Earth. In ?December? Hyabusa 2 will drop a capsule that will parachute into the Woomera test area in South Australia.
During the year there are a series of planet-pairings in the sky. Technically these are called an called an appulse when two planets come closest together as they appear in the sky. These include this year Mars & Jupiter in March, Mars & Saturn in April and Mercury & Venus in May.
And I’ve left the best till last. A Jupiter-Saturn appulse, or meeting, in late December brings the two giant planets close enough that they’ll be easily visible, and in great detail, together through a telescope. They are closest on December 21st & 22nd?but still excellent for a week around those dates. By eye the two planets will appear almost as a single bright ‘star’ in the sky. Such pairings between Jupiter and Saturn occur about once every 20 years but these two planets haven’t been this close since 1961 and won’t be as close again until 2080. For some of us, me included, that makes it a once-in-a-lifetime event. Don’t miss it!
And that wraps up the special events for January 2020.
An excellent companion to Sydney Observatory’s monthly Night Sky Guides is the annual “Australasian Sky Guide”?by Dr Nick Lomb. It’s jam-packed with monthly night star maps and astronomical information, including rise and set times for the Sun, Moon and planets, plus tide times and a detailed look at our solar system and upcoming astronomical events. It’s available from Sydney Observatory or the MAAS store, or you can purchase it online, for which additional costs apply.
And if you’re in Sydney visit the Observatory in the Rocks area. Book in for a night tour to view the skies through our telescopes. Or tour our exhibition for free and discover the history of Australian astronomy.
And that brings to an end this Night Sky Guide from Sydney Observatory and from me, Andrew Jacob. Thank you for listening and I wish you clear skies until next time.