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In 1995, the South African Broadcasting Corporation (SABC-3) commissioned this astronomy television series, in which Thomas Budge visited key astronomical sites, interviewed many prominent astronomers, and taught the television audience how to get the most from their viewing the night sky.

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Outline

The Sun | Tribal Sun Mythology | Zulu Beliefs | Khoisa Beliefs | Aboriginal Myths | Egyptian Sun God | Greek, Aztec and Inca Beliefs | Sutherland Observatory, South Africa | Dr Robert Stobie | Dr David Laney | The Sun, our closest Star | Star Formation | Proto-stars | Star Lifecycles | Sunspots | Solar Flares | Solar Rotation | Magnetic Flux Tubes | Solar Corona | Solar Eclipse | Solar Wind | Aurora Borealis | Solar Observing using Binoculars | Birmingham University's Solar Observatory | Automated Solar and Lunar Observing | Ancient Solar Observatories | Orion Constellation | Star Hopping Techniques | Ancient Greek Mythology about Orion | Betelgeuse | Rigel | Great Orion Nebula | Sirius | The Summer Triangle | Taurus Constellation | Aldebaran | Pleiades | The Planisphere.

Video transcription

From earliest times, humankind must have studied the sun in its journey through the heavens with a sense of awe and wonder as the planet's provider of heat and light. The sun was and still is vital to all life on earth. In pre-colonial African belief systems, the universe was created by a great god and is widely believed to be divided into two parts, heaven and earth. The heavens, which are the home of the great god, are the male part of this division and are also the home of the stars, the sun, the moon, and the sky.

The earth, female, was somehow severed from its celestial partner at the dawn of time. According to some myths, animals bit in two the thong, connecting heaven and earth. Others say it was the fault of their forefathers. The term mother Earth is derived from the African idea of the earth as feminine. While the sun is central to the traditional way of life, determining daily ritual and seasonal variation, it is generally seen as a tool of god, or as he is known in Zulu, Unkulunkulu. The summer moon journeys under the floor of the sky, the sky in Zulu mythology being god's floor, and the stars, the holes that the heavenly cattle herd made in the black celestial mud.

For the Khoe clan of the Khoisan Bushman, the setting sun is the place where all the dead are taken by bees, the great god. As for the Namibian tribal clan, sand, sunset, and sunrise are the place of divinity, as the great god resides where the sun rises, and the lesser god, the dark aspect of this duality, has his home where the sun sets.

The Australian Aborigines believed that the sun and the moon were created out of the first people at the end of the dream time. So, the Sun woman warrior, Prenala, rises each morning with her blazing torch and lights a huge fire to cook her food. At the end of the day, she rests, and then Japara, the moon man with his smaller torch, makes his journey across the sky to overcome night's darkness.

The coastal inhabitants of the Western Cape, pondered the heavens, believing the sun and the moon to be a married couple.

To the Khoi tribes-people, the sun would carry the moon on his back during the day, and at night, the moon would do the same.

To many civilizations, the sun was regarded as simply more than divine, it was god itself!

To the ancient Egyptians, the sun god, Ra was born every morning and transported across the sky in a boat to die in the west. Every evening during the mysterious night, it would be carried under the world to be born again the following morning.

To the ancient Greeks, the sun was the god Apollo who rode across the heavens in a fiery chariot.

This giant Aztec calender stone was used in honour of the sun god, Tonatiuh. Its incredibly fine craftsmanship shows us the divisions of the Aztec year into 20 months, and the cycles of 52 sun years. The Aztecs believed that human sacrifice was necessary to keep the god strong and to ensure the continuity of human existence.

The ruling family of the Inca prayed to the sun, calling it Inti. This all-seeing, scorching light was the origin of life and a symbol of renewal. A common expression among the Inca was that a person who had died had returned to the sun.

 

So, what does the sun mean to us? To learn more about it, I travelled to Sutherland, the largest observatory in South Africa. This remote site was chosen in the Karoo, as it lies midway between the summer and winter rainfall regions, giving astronomers the maximum viewing time possible. It is also far from the large cities, which means that the skies are at their most brilliant.

I've already had a look at the observatory as we came flying in, and in fact, you can just, just perhaps get a glimpse of it on the other side of the hills, about 30 or 40 kilometres away.

On Sutherland's grass airfield, I was met by Dr. Robert Stobie, Sutherland's Director, and Dr. David Laney, a fellow astronomer. The temperature difference from a hot 35 degrees at Kimberley to -2 at Sutherland, caught us all off guard, but we were welcomed with a hot meal and a warm bed to prepare us for our early morning call.

 

Here we are at Sutherland and it is very, very cold indeed, but this is ideal viewing conditions for any astronomer. It's ideal because when it's cold like this, the air is nice and stable. But, here we are in these subzero conditions with these wonderful domes behind us, and the astronomers who have been busy all night, and what are we doing here — waiting for the sun to rise. Now the sun, you may not realise, is in fact our closest star. There are many other stars out there in the night sky, but the sun most certainly is our closest. In fact, we call it our daytime star.

It's quite interesting to go back and see how stars formed. Way out in space were these nebulous regions, these great vast clouds of chemical elements, and inside, these clouds started to collapse because of their own gravity. They collapse in towards the center, and that starts to form proto-stars, right down in the middle of this material that collapses inwards. The stars start to form, and when sufficient material has collapsed inwards, the star then begins to ignite.

We, we tend to think that the sun was always there, always has been, and always will be there to support life on on earth, but that's not true. Every single star goes through an evolutionary cycle. They're born in these clouds that II just mentioned, and then they go through a stage of their existence and end up dying in one of several ways. Some of them in very glamorous ways. Others just sort of turning to cinder.

Sutherland's telescopes are used by astronomers the world over. Here, they spend their nights viewing objects deep in space. The southern skies have particularly rich star fields which attract these foreign visitors.

Well, this shows what we now know about the inside of the sun. You see the light takes about a million years to get outside, for example. But we didn't always have any real information about what was inside? For a long time, basically all we could study about the sun, is what it looked like outside.

The sun is enormous in diameter!

Yeah, it's about a million times the size of the earth. And not only that, we know that it's composed of vast amounts of hydrogen gas, about 70%, and helium gas is making up most of the remainder. It's really a very average star, and in the galaxy of stars that we live in, there are about 500,000 million suns. The earth is a rather undistinguished object about two thirds of the way out from the center of the edge. In Galileo's time, people started looking at smaller sunspots. You'd see them a lot more often because the really big ones don't happen too often. They immediately noticed the sun was rotating.

How, how did they notice that?

From day to day the sunspot move.

Oh, yes, you can actually see how they've changed.

In fact, in the period of about 27 days, the sun spots will do a complete rotation of the sun.

Interesting.

What is the closeup of a sun spot? This dark patch in the middle can be as much as 2000 degrees cooler than the rest of the surface of the sun.

That's not a hole going down into the sun then?

No, not at all. This is just a cooler patch. What's actually happening is the strong magnetic field is blocking heat from rising from the center of the sun to such a great degree as it does out here and the rest of it. In fact, you can just see the turbulent pattern of the heat bubbling up from the inside in what are called granulations. Now granulations are typically about the same size as the distance from Cape Town to Johannesburg.

What are they? They look like some kind of bubbles.

Well, what's actually happening is that in the bright center you've got hot gas, which looks bright simply because it's hotter rising up, and at the edges, it starts sinking back down again, having cooled off a bit. These things have lifetimes in minutes. Now, if you use a special filter to look at a slightly higher layer in the sun, you can see the way that the granules are organized into bigger super granules. They look like bits of combed grass. In fact, what's actually happening is that you are seeing the way that the magnetic fields surrounding a sunspot, organise the material, very much the way that a bar magnet organises iron filings.

Oh, yes. That, that makes sense when you see it like that.

And, in radio waves, you can see these active regions with strong magnetic fields coming out of the sun as bright spots.

And would those be the regions where we would find the sun spots?

Yeah, sunspots typically form in two belts on each side of the sun's equator. So, this is a beautiful example of a gigantic prominence coming out really, from the surface of the sun. This is enormous expanding gas that's really blowing out from the surface, and in a size that's far greater than the earth.

Well, you were talking about the diameter of the sun a little earlier on, and the earth is just a tiny little speck.

I mean yeah, about the size of one of these small black spots. Yeah, this is actually material out in the sun's atmosphere, if you like, but what you're looking at is a denser part, which is rising under the influence of a magnetic field, and it's become strong enough to move it out into the sun's outer atmosphere.

This is a very good example on the surface of the sun where you see magnetic flux tubes. You see these beautiful arcs above the surface, and again, it's a properties of the magnetic fields where the particles are actually streaming out. Yeah, these flux lines and forming these gigantic arcs.

Actually the material above the surface of the sun can often be seen at the solar eclipse.

What are we looking at? Which part of this picture?

This is this is actually the moon's disc blocking the light of the sun.

Oh, I see.

Just a little bit of the sun peeping out through a valley in the edge of the moon. But you can see one of these clouds of denser gas that's risen into the sun's atmosphere, which is condensed out of it. It looks red, of course, because it's hydrogen gas.

Now, is this possible to see with the naked eye?

Yes, it is, during the solar eclipse.

The moon is just the right size to essentially, occult the sun's disc, and then you see at the time of a total solar eclipse, you see this beautiful corona which extends for many radii from the sun, and this is really very hot, enormously hot gases streaming out at a temperature of about a million degrees Celsius.

This is the sun now in x-rays, which are amongst the most energetic wavelengths we can observe, and the sun actually emits x-ray radiation.

You see enormously bright patches here, which are actually again in the Corona. They're very hot, again, temperatures to cause these x-rays to be emitted, whereas in ordinary light, the Corona is very dim, so much so that you can only see it at a time of an eclipse. Particles are streaming out along the magnetic field lines into space, what we call the solar wind When that reaches the earth, disturbances in that solar wind can cause what we call the aurora borealis, the northern and southern lights that you can see in the sky around the north and south magnetic poles.

I've only read about them in books.

They do appear in South Africa once in a great while. It takes a major disturbance in the sun to produce one, but they were visible as far north as Namibia a few years ago.

 

What I've got here in order to have a look at the sun is exactly what you might want to use if you want to have a look at sunspots. These are my binoculars on a simple camera tripod, and what I've done, is I've just simply masked out one of the lenses, just with a stone, so that the light doesn't go through. The light rays in fact, going down through the other part of the binoculars and projecting down here onto this image that you see on the card, and there we can see two sunspots: number one, and sunspot number two.

Now, if you're wanting to have a look at the sun, I certainly encourage you to do so, but one thing you should never, ever do, is to look at the sun through any lenses with the unaided or the naked eye, or through any optical equipment whatsoever. Doing so will cause instantaneous and irreversible blindness, and I really don't want that to happen to you. If you want to have a look at the sun, by all means do so, it's great fun, but you should use a setup like I've got here. Take your binoculars or a small telescope, and project its image onto a card. That's the best way to look at the sun.

Birmingham University in England set up specialised equipment at Sutherland to observe the sun. This is a fully automated telescope that tracks the sun's journey across the sky throughout the day. The telescope is programmed to know just where and when the sun will rise on the eastern horizon and wastes no time in opening its shutters for the day's viewing.

This telescope is one of a network of six telescopes around the world, which that is in Sutherland. Here we have one in Tenerife in the Canary Islands, one in California, two in Australia, and one in Chile. With these stations, basically, we can only observe the sun continuously when it's above the horizon here, but when the sun's below the horizon, then one of the other telescopes will be carrying out the observations. So we get continuous observation as astronomers. We really would like to get to know the detailed composition of the stars or what the stars makeup is, but those stars are so far away. Our very closest star is four and a half light years away. The sun is in fact our closest star, it is much closer than Proxima Centauri, and that affords us a wonderful opportunity of being able to study it, because it's so close to us. We can really be able to make very fine definition measurements and definitions of it, and that allows us to glean a lot of information that we can take and transfer back onto the stars on the celestial canvas at night.

And that's the kind of information that astronomers are gathering here at Sutherland.

 

If anyone knows precisely how this telescope operates, then it must be Peter Fourie.

Okay, this computer here is the main control computer of the entire dome. This is the computer which controls the movements of the dome and the collecting of the data. It also, at the night time, compacts the data so that it can be transferred to the main station, where they will then analyse the data. So, all they do here, is they collect the data and control the dome. The electronics over here controls the ovens in the instrument as well as the actual interface to the computer.

The stuff on the side, on my left hand side here, is the actual control of the dome and the guiding of the telescope. We have to guide the telescope very accurately on the sun, otherwise the movement of the telescope will be seen in the data. So this instrument here controls, locks the telescope to the sun, and the bottom part is the interface to the computer for controlling the dome and the rest of the movements.

I thought this was a solar observatory, and yet over here on this piece of equipment, I see there's a label saying lunar observer. What is that?

In the night time, when the moon is up, the light you see of the moon is still the light from the sun. So, what they can do, is they can actually observe the sun by looking at the moon. So, the variations that you see on the sun here, you can also see on the moon.

We've been looking at the dome opening and closing by itself, and it's been moving around since we started watching this morning, it's moved quite a lot. Is it fully automated?

Yes. That's why it looks so crowded here, because there's normally nobody sitting here. This thing is completely robotic. So, the thing runs completely by itself, we come in here about once a week just to change the disc in the computer.

And what happens when it rains?

Also, it'll shut down itself, and if the wind speed gets too high, it'll shut down completely by itself.

I can't wait to take a look upstairs.

The telescope bristled with as much electronics as the control room below. Attached to it, are several tracking and alignment devices. Whilst the other domes stand closed during the day, the sun monitoring telescope continues to record minute changes in the sun's resonance. Once the data is stored on the disc, it has taken to Cape Town for transmission.

 

People have been observing and recording the sun's movement since the beginning of time.

Ruins of ancient solar observatories, like Stonehenge, are found across the world, indicating the vital role that the sun played in managing human activities.

I'm really thrilled to find a markup of an ancient solar observatory here in the back garden of Sutherland. A number of stones placed in a particular order, and when these stones align with the setting sun, then one is able to determine the various seasons. You can see a stone over here and, if we have a look at the shadow that is cast by this stone, you'll see that it almost lines up with that stone over there, which means that this is sometime just shortly after Equinox, the earth is tilted in its orbital plane.

During the course of the year, the sun appears to move along the horizon. Its position can be marked with a suitable object like a stone. As it changes from summer to winter, in simple terms, the sun appears to oscillate across the sky from south to north and back again as the seasons change.

 

Hi, and welcome to Sky Watch, where we take a closer look at the starry sky, as you would see it tonight after this program.

In particular, we'll look at Orion and with a really easy and fun technique called star hopping, we'll be looking at other bright stars and constellations around it.

The way we measure star distances is in light years, the distance it takes for light to travel in a year. Distances between objects in the universe are so vast that the earthly unit of kilometre is absolutely useless.

Look at this calculation: Light covers a distance of 300,000 kilometres in one second. If we multiply this by 60, we get light's distance in a minute, and again by 60 gives it's distance in an hour, multiplying it by 24, we get it's distance in a day, and by 365 it's distance in a year. That is nearly 10 million, million kilometres.

Our nearest neighbour, Alpha Centauri, is four and a half times that distance away from us.

Now, how much easier is it for us to say that Alpha Centauri is four and a half light years away, than it is for us to say 45 million million kilometres away?

The Orion star pattern is easily recognised as a giant hunter with three bright stars aligned in a straight line along his belt. The other stars clearly plot out the hunter's raised club in his right hand, and a lion's skin in his left. In Greek mythology, one story goes that Artemis, goddess of the moon, fell in love with Orion and neglected her task of lighting the night sky. Her twin brother Apollo, seeing Orion only as a bright dot swimming far offshore in the sea, challenged Artemis to see if she could hit the target with an arrow, not realising that this was Orion, Artemis shot and killed him.

Later, when his body washed up on the beach, she saw what she had done, and was overcome with grief inconsolably. She placed his body in the sky together with his hunting dogs. This, they say, explains why the moon has such a sad and cold appearance.

Finding Orion is quite easy. Locate a point along the horizon east, northeast, and then follow a line upwards from the horizon some 30 to 40 degrees. Here you should see Orion's belt, three bright stars in a straight line, which is tilted with respect to the horizon. Most of the large constellations lying towards the north appear to be upside down when viewed from southern latitudes, and Orion is no exception. The great hunter is orientated in the southern sky so that he lies on his right shoulder.

This is the bright yellowish star, a few degrees to the left and below the belt. Its name is Betelgeuse, a red super giant star, one of the largest super giants known to astronomers. It lies 652 light years from Earth and has a diameter some 800 times larger than that of the sun. With the use of some sophisticated scientific instrumentation, large dark spots were revealed on the star's surface. It is also an interesting star as it changes its brightness over a period of five years.

A super giant star is a massive, old star, nearing the end of its existence. Stars, like Betelgeuse, generally come to a catastrophic end in what we call a supernova. When this occurs, so much energy is released that it can outshine an entire galaxy of stars.

Rigel is the star near Orion's left foot. It's the bright one a few degrees up and to the right of the belt. Its Arabic name means leg of the giant. Again, this is a super giant star, some 250 light years away. Hanging from the belt is Orion's sword. A discernible line of stars generally pointing towards Rigel. With the naked eye, these stars look very much like any other stars, but on closer examination, and on a very dark night, you'll see some faint fuzziness, especially around the middle star.

This was a great opportunity to use a pair of binoculars.

Having located Orion's belt, you can use it as the starting point to readily find other celestial objects. This is what we call star hopping. Follow an imaginary line drawn down through the belt stars of Orion until you come to Sirius, some 20 to 25 degrees above the Eastern horizon. This is the brightest star in the night sky. It is relatively close at a distance of only nine light years away. What looks like a single star to the naked eye, is in fact a pair of stars orbiting around each other. Their orbital period is some 50 years, and with a modest telescope, you should be able to identify two separate stars.

The primary star is a hot white star. Its companion is a white dwarf. A white dwarf star is again an old star that has come close to the end of its existence. Its fuel supply has been exhausted and the remaining matter collapses in, it's compressed under its own gravity.

Following the imaginary lines through the belt in the opposite direction, you will find the distinctive upsidedown V of Taurus. The reddish star, Aldebaran, is at the eye of the mythical bull, and the v-shape represents the bull's upside down face. Continue with your imaginary line for a little while past Taurus to the seven sisters, properly known as the Pleiades. This open cluster contains between 300 and 500 newborn stars in a sphere, some 30 light years in diameter.

Lying between the stars is the bright reflection nebula of cold gas and dust, which appears bluish in color. These fascinating objects will remain visible throughout summer, although they will move progressively westwards during the coming months.

Probing these regions with a pair of binoculars or a small telescope will be a very rewarding exercise. You might want to use a planisphere to guide you. It is basically two rotating discs. The one disc containing a map of the night sky from a particular latitude, and the other a horizon mask. When these discs are rotated one over the other, they show you the night sky for any night of the year. It is available from leading bookstores and the Planetaria.

Until next month, wishing you clear night skies.



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