September 2016 night sky guide podcast, transcript and sky chart

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 Education Program Producer.
Geoff fascinates us with his guide to the stars and constellations to look out for in September and also with insight into how astronomy was important to the ancient people of Mesopotamia, Greece and Rome. Geoff also tells us where and when to look out at night for the planets Mercury, Jupiter Venus, Mars and Saturn in September.

Listen to the September 2016 night sky guide audio, or read the transcript below.

Hear the Audio
You can subscribe with iTunes or upload the (34 mins) audio to your iPod or mp3 player, or listen to it on your computer.

See the Sky Chart
We provide a September 2016 night sky chart (PDF) which shows the stars, constellations and planets visible in the night sky from anywhere in Australia. To view PDF star charts you will need to download and install Adobe Acrobat Reader if it’s not on your computer already.

Read the Guide
Hello there. I’m Geoffrey Wyatt, one of the team 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 month of September.

Originally September was the 7th month after all the Latin septem, means “seven”. When January and February were added and the order rearranged it became the 9th month that we have now.

What we’re going to do is a tour the night sky so of course you’ll need some provisions. Somewhere warm to sit, a blanket perhaps, a cup of coffee or if you’re old enough a glass of red wine to assist your imagination. One of the most important things that you can have with you is your printable map that you can download from our website. I want you to find a high position so that you can see as much of the horizon as you possibly can in all four cardinal directions. That’s right: North, East, South, and West. If you’re up against your neighbour’s tree or house, then of course you’re going to lose some of the view, but some of us just can’t help that. So make do with what you’ve got, but if you can, a clear view in all directions will make all the difference.

Wait for sunset and then a little more until it’s nice and dark perhaps an hour or so after sunset. Look up and what do you see? Clouds? Possibly. Stars? Hopefully. ‘For some, who are travelers, the stars are guides. For others they are no more than little lights in the sky.’ (The Little Prince by Antoine de Saint-Exupéry) and I want us all to be travelers together and we shall begin by looking toward the western horizon. From there, go straight up to about 60 degrees. Yes, that’s right I’m sure you’ve heard me talk about this before. 60 degrees – how can you measure that? Most of us can estimate 90 degrees or straight up. Most of us can also do half way, 45 degrees, but 60 degrees?

A handy way of measuring what you can see in the sky is to hold your hand at arm’s length. If you clench your fist, that will measure about 10 degrees. If you hold out your pinky, that will be about one degree, or twice the size of the full Moon. If you spread your hand from pinky tip to thumb tip that is about 20 degrees.

Our first point, due West, where the Sun has gone down, is about 75 degrees up, so that’s just under four hand spans. As we go up we bypass the very famous group of stars called Libra which I’m sure you’ve heard of it but it’s not well positioned at this time of year.

The first bright star you come to is the third of – though it is quite archaic – four royal stars. It is a bright star that used to measure one of the four important points in the sky – the solstice and the equinoxes. This was done thousands of years ago from Mesopotamia, the wonderful cradle of civilization between the Euphrates and the Tigris rivers.

It is the 15th brightest star in the night sky. It’s a red supergiant, which means, of course, it’s a pretty big star. It’s about 15 times the mass of the Sun, 800 times the diameter of the Sun and 600 light years away. It is, Antares. It is the brightest star in the group of stars, or constellation, that we call Scorpius.

I want you to find a high position so that you can see as much of the horizon as you possibly can in all four cardinal directions. That’s right: North, East, South, and West. If you’re up against your neighbour’s tree or house, then of course you’re going to lose some of the view, but some of us just can’t help that. So make do with what you’ve got, but if you can, a clear view in all directions will make all the difference.

Wait for sunset and then a little more until it’s nice and dark perhaps an hour or so after sunset. Look up and what do you see? Clouds? Possibly. Stars? Hopefully. ‘For some, who are travelers, the stars are guides. For others they are no more than little lights in the sky.’ (The Little Prince by Antoine de Saint-Exupéry) and I want us all to be travelers together and we shall begin by looking toward the western horizon. From there, go straight up to about 60 degrees. Yes, that’s right I’m sure you’ve heard me talk about this before. 60 degrees – how can you measure that? Most of us can estimate 90 degrees or straight up. Most of us can also do half way, 45 degrees, but 60 degrees?

A handy way of measuring what you can see in the sky is to hold your hand at arm’s length. If you clench your fist, that will measure about 10 degrees. If you hold out your pinky, that will be about one degree, or twice the size of the full Moon. If you spread your hand from pinky tip to thumb tip that is about 20 degrees.

Our first point, due West, where the Sun has gone down, is about 75 degrees up, so that’s just under four hand spans. As we go up we bypass the very famous group of stars called Libra which I’m sure you’ve heard of it but it’s not well positioned at this time of year.

The first bright star you come to is the third of – though it is quite archaic – four royal stars. It is a bright star that used to measure one of the four important points in the sky – the solstice and the equinoxes. This was done thousands of years ago from Mesopotamia, the wonderful cradle of civilization between the Euphrates and the Tigris rivers.

It is the 15th brightest star in the night sky. It’s a red supergiant, which means of course, it’s a pretty big star. It’s about 15 times the mass of the Sun, 800 times the diameter of the Sun and 600 light years away. It is, Antares. It is the brightest star in the group of stars, or constellation, that we call Scorpius.

A light year is the distance that light travels in a year in the vacuum of space. It’s a long way. For those of you who like mathematics, it’s 10 to the power of 16 metres. For those of you that like kilometers, it’s roughly 9,500 billion kilometres. It’s not a convenient way of thinking about it to be honest, so we tend to use just a ‘light year’.

You’re seeing this star is as it was about 600 years ago. You are looking back in time.

Antares, its name came about because every now and then, roughly every 800 days or thereabouts, the planet Mars wanders fairly close by. The Greek name for Mars was Ares. As Ares, god of war, would go past this fairly bright reddish star they looked similar. This star was called the rival of Mars, anti-Ares, Antares.

As I’ve mentioned, this star was one of what we called the four Royal Stars – which were markers in the sky. They were the bright stars near significant points that traced the movement of the Sun though the sky: the equinoxes and the solstice. None of these stars do so now because the Earth does a rather slow 26,000-year wobble on its axis which we call the precession of the equinoxes.

It has the effect of moving the four points against the background stars. Antares therefore used to mark a position in the sky known as the autumnal equinox but not now. It will again in around another 20,000 years, but who cares? We’re not going to be around for that.

When you look into the night sky, you might be able to see around 2-3000 objects depending on your age and eyesight. The vast majority are stars. It’s very hard to remember which one is which unless you have a memory aid, something to help you. A dot-to-dot picture with a good story behind it is a fairly handy way of doing it.

To the ancients, the area of sky that we’re looking at now appeared like a small but nasty animal. Antares marks its heart. There’s a star on either side which should make up the body. If you go down just a little bit toward the West, there’s a perpendicular line of stars, which will be the head and claws on either side.

Claws, head in the middle, go up through a line of three stars with Antares in the middle then curling up around will be the long and dangerous tail of the scorpion. Scorpius is a constellation and a constellation is simply a region of the sky. Think of it as being like a suburb. There are many suburbs in a city. As soon as someone mentions a particular one it gives you a rough idea of where it is and it’s the same with the sky.

Over thousands of years the sky has been mapped and broken up into, now, 88 different sky suburbs or constellations and Scorpius is one of the more famous. It has many good stories about it but as you can imagine the story that we have now may not be the same as it was thousands of years ago.
One that I particularly like revolves around another very famous constellation, the mighty hunter Orion. He boasted that he could kill any animal on the planet. This displeased Artemis, the Goddess of the hunt, so she created the giant scorpion ‘Scorpius’ to kill him.

So epic was the battle that even Zeus himself, the king of the gods, stopped what he was doing and watched the fight. Ultimately Orion was killed by the Scorpion and Zeus placed the scorpion in the sky for us all to see.

But Artemis took pity on Orion and placed his body in the sky as well but on directly the opposite side of the sky so that the two would never fight again. This very simple stick figure of a scorpion has a wonderful story behind it.

When you’ve been able to see the full constellation of Scorpius, if you have a pair of binoculars or a small telescope, scan around the tail region. There are some nice objects there including some lovely clusters of baby stars called M6 (The Butterfly cluster) and M7. They’re simply the sixth and seventh objects in the catalog developed by a man whose name began with M. It was done quite some time ago but we still use it and these are rather pretty groups of young stars.

Once you’ve done that go a little bit higher but you will need to have the printable map because the next group of stars is rather hard to see. What you are looking for is a half-man half-horse with a bow and arrow. Can you see it? I’ll give you five seconds.

Found it yet? I don’t think so. It’s nearly impossible. If you can see a half-man half-horse with a bow and arrow you’re doing very well or perhaps you’ve been shown because it looks much more like an old-fashioned teapot.

Yes, that’s right. Those of you out there with the birthday star sign of Sagittarius – you’re now a teapot, unofficially of course. This group of stars is fairly important to look at because it marks the centre of the Milky Way galaxy.

If you can get away from the bright city lights and there’s no Moon and you look up at this time of year you should be able to see a glorious view of Via Lactea, ‘By Milk’, our galaxy, the Milky Way. It is breathtaking. It’s beautiful and away from bright lights, September is a wonderful time to look up and enjoy it.

Try and find the teapot because if you do find it and in particular the spout, roughly 26,000 light years in that direction is the heart of our galaxy and an object called Sagittarius A*. (Pronounced Sagittarius A Star)

It is a massive black hole roughly four million times the mass of the Sun. NASA’s Swift space telescope has been observing it and in 2014 gave astronomers enough data to work out that it’s roughly 44 million kilometres in diameter. Black holes are rather bizarre objects. At the centre of the black hole there is something called a singularity, a point, a mathematical point with infinite density. Oh dear, that makes my head hurt.

Around that singularity there is a sphere, a sphere of influence called the event horizon and that event horizon is the part with a diameter of 44 million kilometres. Travel over the event horizon and…uh-oh, it’s not good times ahead. In fact, we call it ‘spaghettification’, ripped apart atom-by-atom. But we don’t know for sure what happens once you go over that because you leave the observable Universe.

Let’s move along from Sagittarius and start to head down toward the East. You might have to actually turn around a little bit so you’re now facing the East. The next constellation down is the first of the water signs.

It’s a fairly faint group of stars. What I want you to look for is a group that looks a bit like a triangle that’s been bent. Technically I suppose that makes it a quadrilateral and what you’re looking for is Capricornus the half-goat half-fish.

When was the last time you bumped into an animal that was half-goat half-fish? No. Not likely, is it? Again, it relates to having an interesting story to help memorise the positions of the stars. People have been doing this for thousands of years, dot-to-dot pictures. It’s a very useful way of remembering things.

I should point out of course that not all cultures do dot-to-dot pictures. The Indigenous people of Australia have often used just a single point, a single star, to tell a story but at the moment we’re still looking at Capricornus, half-goat half-fish.

The story goes that the gods were having, effectively a picnic, when suddenly the Earth cracked open and the demon Typhon came out. Typhon attacked Zeus, king of the gods.

The goat Pan did the only obvious thing that he could do at seeing such a fight, he panicked, which is where we get the word from, and thought to himself, “I’m out of here”. He started to change from his goat form into a fish to swim to safety. He got halfway through the transformation and thought, “Zeus is the boss. I’d better go back and help.”

He played a shrill note on his pan pipes which distracted Typhon long enough for Zeus to gain the upper hand and scare him off with a thunderbolt. As a reward for his assistance Zeus placed Pan as he was in the sky as a half-goat half-fish.

Amazing imagination. I just love it. An interesting thing to note about this particular constellation as well is that it was in this part of the sky on September 23rd, 1846 that the planet Neptune was discovered by the German astronomer Johann Galle.

The planets, or “wanderers” as we used to call them, stick to a line across the sky called the ecliptic. You’ll never find the planets, the Sun or the Moon down near the Southern Cross or near the Big Bear, Ursa Major in the northern sky. They will always stick very close, not necessarily on, but close to the ecliptic. No wonder the planet Neptune was found in this part of the sky as it passes right through Capricornus.

As we leave Capricornus I want you to just go down a little bit more. This constellation is also very hard to see but once it’s been shown to you I think it’s not that hard. All you’re looking for are the shoulders, the jug and the line of water flowing from the zodiac constellation of Aquarius the water carrier.

He was the most handsome youth ever and was carried from the Earth up to Mount Olympus by Aquila the eagle where he became the water bearer.

I take it back, it’s actually pretty hard to see but from Aquarius there is a line of stars that seems to meander across the sky to a bright star that you can see about 30 degrees, so that’s one hand span and one clenched fist above the eastern horizon. It’s a relatively bright star. Guess what? It’s another one of our Royal Stars. It is Fomalhaut, the mouth of the southern fish or Piscis Austrinus and long ago Fomalhaut used to mark the position of the winter solstice as seen from the northern hemisphere, it is the Sun’s most southerly position but remember because we’re talking about this as a Royal Star this was thousands of ago so it’s no longer the marker. That point has moved on because of the Earths precession of the equinoxes. Everything has rotated through the sky.

Fomalhaut is a fairly young star. It’s only about 400 million years old and about 25 light years away. At twice the size of the Sun it’s pretty big.

After you’ve been able to see Fomalhaut…. by the way, the rest of the constellation to me looks a little bit like a paisley swirl with the brightest star at the bottom of it as we’re looking at it right now. What I want you to do is turn to your left, that means we’re going towards the North.
It’s pretty hard to see but we’re going to go past the constellation of Pegasus which will look a bit like a big square, though it’s very low at this point in time. We go a little bit further toward the North past another group of stars that looks like a large faint cross. You’d need a perfectly clear view toward the North to see this one. It is the constellation of Cygnus the swan the home of the first suspected black hole ever found and it’s called Cygnus X1.

Go a little bit past that and what you’re looking for is the fifth brightest star in the night sky. It’s only about 18 to 20 degrees above the horizon. Remember, as we said before that’s roughly one outstretched hand, pinky to thumb tip, above the horizon. You’re looking for the fifth brightest star in the night sky – Vega.

Again, like Fomalhaut, it’s only about 25 light years away and about twice the mass of the Sun. It’s less than 500 million years old so it’s a young star but the cool part is 12,000 years ago it was indeed the North Polar Star.

It seems that many people think that the stars never move but they do. They do move and the patterns change over very, very long periods of time. The Earth also wobbles as I’ve mentioned. 12,000 years ago it was the Polar Star and roughly in another 14,000 years it will be the Polar Star again but don’t worry about waiting for that one.

I love looking at this star the fifth brightest star called Vega. By the way, again, for the science fiction buffs, it was the destination star in the fabulous 1956 movie ‘Forbidden Planet’.

If you go from Vega at roughly 18 degrees above the northern horizon up to about 35 degrees, that’s one hand span with the fingers wide open, one clenched fist and then half a fist. Got that? Good.

If you can do that you will see another fairly bright star. This is Altair ‘eye of the eagle’. That was the eagle that carried Aquarius up to become the water bearer.
Vega and Altair, the two bright stars are separated by the Milky Way, the river in the sky. Throughout Asia on the 7th of July legend says that birds come together and build a bridge over the Milky Way so the two can be together for just one day.

Oddly, nothing actually happens in the sky but I love this story and in Japan the girl, Vega is Orihime, meaning the princess and the boy is Hikoboshi. In China it’s Zhi nu and Niulang. My pronunciation however may be off somewhat so please forgive me there. This story is also quite famous in Vietnam and Korea. The sky really is a multicultural delight.

Continue now to turn to your left past where we started. To the southwest we’re looking for a second centaur half-man half-horse and this ones’ name is Chiron. He was a wonderful teacher. According to mythology from long, long ago he was the tutor to Achilles, Hercules and Jason.

What we’re looking for is a fairly bright star that makes up one of his front feet. Its altitude is about 45 degrees above the horizon. How do we do that? Aha of course, two hand spans, pinky to thumb, that’s about 40 degrees, then half a clenched fist up. If you can see one bright star there you’ve nailed it. That’s Alpha Centauri. It’s the closest star to us after the Sun and the third brightest star in the night sky.

The interesting thing about this star Alpha Centauri is that it’s a visual binary which means that if you have a small telescope or even a really good pair of binoculars this one star looks like two snuggled up against each other.

In reality they’re not. The distance between them varies enormously. They’re in a dance. A dance that takes roughly 80 years for them to go around each other once. At their closest they’re roughly the distance from the Sun to the planet Uranus. At their most distant nearly double that from the Sun to Neptune. One of them is a little bit bigger than the Sun, one of them a little bit smaller, but it’s a little more complicated than just being a binary star because there is a third star in the system. The third star is a small red dwarf going around the other two going around one another. The third star comes closer to us than other star apart from the Sun and it’s called Proxima Centauri at 4.24 light years. Recently in the search for exoplanets, a small planet just a little bigger than the Earth has been detected in orbit around Proxima Centauri. It takes about 11 days to go around once so it’s very close to the parent star but because it’s not as big or as hot as the Sun that actually puts this planet called ‘Proxima B’ into what’s called the ‘Goldilocks’ zone. Theoretically it means that liquid water may exist on this planet. Stay tuned because I am sure over the next few years there will be more studies and information released about this intriguing new and close exoplanet.

Just below Alpha Centauri is the second brightest star in the Centaur so it is called Beta Centauri. It represents another of the front feet of the half-man half-horse. From there there’s a line of stars that, again, you’ll need the star map to see, that wraps around indeed the smallest of all 88 constellations and that is the Southern Cross. It’s getting a bit low in the southwest at this stage and too hard to see.

Keep going around to your left, past due South and into the southeast. You’ll see the 10th brightest star in the night sky. That is Achernar the brightest star in the constellation of Eridanus, the River.

It’s an amazing constellation because it winds its way across so much of the night sky. It’s an interesting star too at about 140 light years away, it’s seven times the mass of the Sun but 3,000 times brighter. It’s very, very bright, but because of the distance it fades to being about the 10th brightest.

It’s also intriguing because it spins so quickly its equatorial diameter is about 56 percent wider than it’s polar. That makes it one of the flattest stars we’ve ever seen.
When we look up and see stars we see mostly single points of light scattered here and there but that is not the reality. The majority of stars come in groups of two or more and they are as close to immortal as we can imagine. Our galaxy, and indeed the universe, is a very unusual and beautiful place.

Special Events for September 2016
Special events for September 2016 and let’s start with the Moon.

New Moon is on Thursday the 1st at 7:03 pm.
First quarter Moon will be on Friday the 9th at 9:49 pm
Full Moon is on Saturday the 17th at 5:05 am, and
Last quarter Moon on Friday the 23rd at 7:56 pm.

The spring equinox will occur on Friday the 23rd at 12:21 am. This is simply when we see the Sun move from the Northern Hemisphere and cross the celestial equator into the Southern Hemisphere, which for us signals the start of spring. In the Northern Hemisphere however it’s the autumnal equinox. The Sun will rise due East and set almost due West.

Sunset at the start of the month is 5:37pm and by the end of the month its 5:57pm, so a 20 minute difference.

Sunrise at the start of the month is 6:14am and by the end of the month its 5:34am, so a 40 minute difference.

Three planets, Mercury, Jupiter and Venus will be huddled in the West immediately after sunset at the start of the month in Virgo but very hard to see unless you have a perfect view to the West and clear sky. Mercury will be lost by the end of the first week and Jupiter by the second. On the 3rd the young Moon is just below Venus.

On the 8th the Moon will be close to Spica the brightest star in Virgo.

Mars and Saturn are close to each other with Mars moving from Scorpius into Ophiuchus then Sagittarius. On the 8th the Moon is close to Saturn and on the 9th close to reddish Mars.

Of course with all 5 planets visible in the evening sky none will be seen in the morning.

You can find our monthly sky guide podcasts on iTunes. If you want more detailed sky maps, sunrise and sunset times, the Moon and tidal times, and a whole lot more, we recommend that you buy the book ‘The Australasian Sky Guide’, by Dr Nick Lomb.

It’s available from Sydney Observatory and the Powerhouse Museum websites and shops. It’s only $16.95 if you come to our venues but a little bit more with postage and handling if you order online.

Our website at has a galaxy of information about astronomy and visiting us at Sydney Observatory, how to use telescopes, see a program in our Space Theatre, and visit the new Sydney Planetarium.

For the very most up-to-date information, why not engage with us via Facebook? You can also follow us on our Twitter account, @sydneyobs.

My name’s Geoffrey Wyatt, I’m one of the team here at Sydney Observatory and the Museum of Applied Arts and Sciences. I hope you enjoyed this tour of what’s visible in the southern sky for the month of September 2016.

Share

One response to “September 2016 night sky guide podcast, transcript and sky chart

Leave a Reply

Your email address will not be published. Required fields are marked *