Conceptualisation and technical information provided by: Marion West (SARAO) and Puleng Tsie (Sci-Enza)
Editor: Edward Allemann
ISBN – 13: 978-0-7961-8349-1
Published by BK Publishing (pty) ltd Reg: 2015/060893/07
1239 Francis Baard Street, Hatfield, Pretoria, 0083, South Africa
www.bkpublishing.co.za
This project, commissioned by NRF and SARAO in collaboration with SCI-ENZA UP aims to raise awareness of South Africa’s work in astronomy.
Have you ever looked and… wondered…? up at the night sky
What are those bright lights, the stars, scattered in the darkness of the night sky? How near, or far away, are the stars from our planet, Earth?
Throughout history, people have looked up at the sky and asked the same questions. Past civilisations have studied the skies and observed that the Sun can be used to tell time, the Moon can be used to determine the length of the month, and the stars can be used to determine the seasons of the year. The stars have been especially important in terms of knowing when to plant crops, when to harvest, and what season will be best for hunting game.
All over the world, we have connected the dots in the night sky to make patterns, which we call ‘constellations’. In different cultures, each constellation has a particular name and stories associated with it. Constellations have also been useful in telling important times in each season.
The stars and constellations that we see are just a small part of our Universe. Our Universe is the biggest laboratory we can ever explore and it is also the ‘laboratory’ in which we live our daily lives.
In this book, we invite you to explore the laboratory and learn more about the Universe, the things we can see with our eyes, and the things we can only observe with specialised technology. Learn about the electromagnetic spectrum and light, and peek into the deepest parts of space.
Join me, Naledi, as I learn about the cool science and technology that happens right here in South Africa and the great discoveries that our scientists have helped uncover.
We’re nearly there, Naledi...
Look!
Oh my, that’s wonderful. It feels like I could reach out and touch the stars.
But Umkhulu, it’s very dark out here.
Sometimes we need to get into the dark to see the lights. What do you mean?
Beautiful, isn’t it? But the light from those stars has travelled millions of years to get to us tonight.
Did you know that there is so much more out there that we can’t see with our eyes?
Scientists who study the sky, astronomers, use telescopes and special equipment to see more.
Why can’t I see the stars so clearly back at home?
Our galaxy, the Milky Way!
The sky is very clear here. But, at home, the city lights mixed with dust and pollution make it difficult for starlight to shine through.
Thank you for bringing me here Umkhulu. I think that one day, I would love to study the stars.
Questions as old as time What did the ancients know about the stars?
Astronomy is as old as mankind. Ever since people looked up at the night sky and saw the stars, they began to use them to determine times of the year and the seasons. The ancients in Southern Africa also looked to the stars and constellations for useful information, to tell stories, and also for answers to life’s questions.
The Southern Cross and its pointer stars were seen by many southern African nations as giraffes. In Venda culture, when the giraffes, or Thutlwa, poke their heads above the trees it is October, and the end of the planting season.
We use our imagination when we try to make sense of things without knowing what they are. But through science and scientific thinking, people have pieced together the real magic of our universe.
the San people, the Moon tells the story of a man who angered the Sun. Once he is full, theSun cuts away pieces from him each night until there is nearly nothing left. The Moon begs for his last piece to be given to his children, allowing the Moon to grow again.
The Milky Way tells the ancient San story of a young girl who got upset with her mother. Her mother did not want to share her meal of roasted root, so the girl picked up the root and the ashes from the fire and flung them up into the sky, where they stayed.
The three stars in Orion’s belt were seen by different San groups as either male and female tortoises, three zebras, or a man, a dog and an antelope. The star Betelgeuse, in the Orion constellation, was seen by some as a hartebeest.
Amirreza
Kamkar/IAU
OAE
Benoit Knox
For
susan-lu4esm
(pixabay.com)
... and Galileo, one of the ‘fathers’ of modern science, was the first to make a telescope and turn it toward the stars.
As our telescopes were able to see more light, we discovered more planets and moons in our solar system.
A telescope uses lenses to magnify and focus light from the sky.
What he discovered with his telescope forever changed mankind’s view of the Universe.
We’ve seen black holes and supernovae and found planets in other solar systems.
We continue to discover new things all the time!
... We found out that our Sun is just one star among billions of stars in our galaxy, the Milky Way...
Did you know South Africa plays an important role in these discoveries?
Over time telescopes have been improved and been made bigger which has led to more discoveries about our Universe.
And that our own galaxy is only one of many billions of other galaxies.
And now is a good time to tell you that we are planning a class trip to the SALT, the Southern African Large Telescope...
... where we will learn about the amazing technology and the people who work every day to extend our knowledge of the Universe.
We have amazing technology and our scientists collaborate with others around the world.
Cool!
Yay!
Awesome!
Wow!
SALT
South Africa’s large eye on the sky
Location
Sutherland is a small town deep in the Karoo region of the Northern Cape. It is so remote that there is no light or air pollution like we get in our cities. Its clean air, coupled with its high altitude, means that the stars are particularly bright and clear.
This is the reason why Sutherland is the perfect location for the South African Astronomical Observatory Field Station (which is located on a hilltop nearby at 1798 metres above sea level) and its world-famous SALT (Southern African Large Telescope).
The mirror, which focusses the light coming from space, is 9.8 x 11.2 metres in size and made up of 91 hexagonal segments, which are very finely adjusted.
South African Astronomical Observatory
Field Station
The field station is home to a range of very powerful and important telescopes, which are connected to international astronomy projects and experiments.
SALT
SALT is the largest single telescope in the southern hemisphere. It gathers 25 times more light than any other telescope in Africa. That would effectively allow it to see a candle flame on the Moon.
It is an optical telescope which means that it collects light using a large mirror, which is focused onto instruments.
Significance
SALT allows South Africa to make a unique contribution to modern astronomy because the southern hemisphere’s sky contains important objects which do not appear in the northern hemisphere’s sky. Some of these objects are key to measuring the size and age of galaxies and the Universe.
Pretoria
Cape Town
Sutherland
Can we see everything in the Universe with this telescope?
What is the electromagnetic spectrum?
Some astronomers use SALT to investigate how galaxies develop. This galaxy is very similar to our own Milky Way.
This SALT image shows a star nursery, an area of space where new stars form.
No, there is still so much more to see, and not all of it is visible to humans.
With other telescopes we can see more of the electromagnetic spectrum
Southern African Large Telescope (SALT)
Southern African Large Telescope (SALT)
Electromagnetic Spectrum The
Notalllightisvisible
Did you know that light is made up of little particles called photons, which travel in waves.
Photon Wavelength Light source Wave
Although light is all around us, the light we can see is only a small portion of what we call the electromagnetic spectrum.
This spectrum contains a whole range of different waves, most of which are invisible to our eyes.
Electromagnetic Spectrum
Invisible light waves
Visible light
RADIO WAVES
MICROWAVES
To ‘see’ these invisible waves, we have developed special telescopes.
We observe each part of the electromagnetic Spectrum with different telescopes
INFRARED
VISIBLE LIGHT
On one end of the spectrum are radio waves. These waves are long, invisible waves that help us listen to the radio and watch television.
MeerKAT (array of 64 dishes), for radio waves and microwaves from space.
Microwaves are short but powerful waves. We use them to vibrate water in food. This creates heat, which warms up our food in the microwave oven!
Infrared waves are invisible to our eyes, but we feel these waves through heat. Some animals, like snakes and bats, are able to see infrared light.
The only part of the electromagnetic spectrum humans can see is visible light. Visible light is made of waves that we see as different colours.
and
from space.
HartRAO, used to observe radio waves
microwaves
James Webb Space Telescope, used for infrared light.
the STScI
SALT, used to observe visible light from space.
Radio waves everywhere
What are radio waves
Radio waves are among the types of invisible waves. Radio waves are low energy waves with the longest wavelength on the spectrum. They travel a very long way and carry information between different parts of the Universe, but can be hard to detect.
What can radio waves teach us about the Universe?
Radio telescopes allow scientists to study objects that are in space and sometimes very far away. Radio waves can pass through clouds of dust and gas, which block visible light. This means that, using radio waves, scientists can study the early stages of the lives of new born stars, which form deep within these clouds.
• Antennas are used to collect incoming radio waves.
How do we detect radio waves?
Scientists use radio telescopes to detect radio waves from space. These telescopes have three main parts:
ULTRA VIOLET
X-RAYS
Ultraviolet waves come from the Sun. They are short waves that are able to go through human skin and create vitamin D in our bodies.
• Receivers/amplifiers help to boost weak radio signals to measurable levels.
X-rays are very small waves that are able to go through human flesh, but not bone. This is why they are used by doctors to look at bones!
• Recorders keep record of the signals received by the antennas and processed from the receivers/amplifiers.
GAMMA RAYS
Gamma rays have the shortest wavelength in the spectrum. Some gamma rays come from outer space and are the most powerful waves on the spectrum.
X-Ray telescope
Radio telescope
Infrared telescope
Optical (visible light)telescope
This is what it looks like when all the different photos of the galaxy Centaurus A are combined to make a composite image.
Below are photos of the same galaxy, taken by different telescopes.
Radio Telescope is located in an isolated valley near the Magaliesberg Mountain range, around 50 km north-west of Johannesburg. Being far away from everything is important because, even though light pollution wouldn’t be a problem for a radio telescope, electronic devices can cause ‘radio wave pollution’.
The HartRAO-26m telescope is the most accurately known position on the African continent.
What does it do?
HartRAO is a radio telescope, which means that it collects invisible radio waves that have come from space. These waves can be studied to learn a lot about our universe as well as our own planet. There are two separate radio telescopes on site, the 15 metre wide and a 26 metre, which look at different parts of the electromagnetic spectrum.
HartRAO gives students and lecturers from South African universities the opportunity and space to do important research.
Pretoria
Cape Town
Hartebeesthoek
Significance
Using HartRAO and other telescopes from Australia, Europe, Asia, and North America, we can form an ‘Earth-sized’ radio telescope, which gives us very detailed information about objects in space and our own planet. This is called Geodesy. HartRAO is the only radio telescope in Africa that can help with this.
We can also use this ‘Earth-sized’ telescope as a single instrument, which lets us make very detailed images of objects in our Universe that are very far away, including the most remote galaxies scientists have been able to detect.
SkyMap
A
HartRAO was used for SkyMap, which is a map of energy emissions from our Milky Way galaxy and other objects in the southern hemisphere’s sky. These emissions are radio waves with a frequency of 2.3 GHz (2300000000 Hertz!). These observations began in the early 1980’s using the HartRAO 26m Radio Telescope, and took many years to complete!
tracking us in the universe Geodesy
HartRAO is an important site for global navigation systems, and helps tell GPS satellites where they are in relation to the Earth, so that people can find their way around, and scientists can track how the Earth changes.
Geodesy uses far away galaxies as measurement points. This information can be used to gather very accurate information about the Earth, like how fast it spins. Satellite Laser Rangers are used to work out where navigational satellites are, like those used for GPS. Using very well located points found through Geodesy, like the 26m radio telescope at Hartebeesthoek, these satellites can help us find our way around. Without the accuracy that Geodesy gives us, these locations would be so wrong that we would still need to use paper maps.
This is what a single optical telescope can see.
This is what a combined, ‘USA sized’, radio telescope can see.
This is the detail that is achieved with a combined, ‘Earth-sized’ radio telescope.
This is what HartRAO can see on its own.
Jacoline Schoonees/DIRCO Laser
These images of the galaxy Centaurus A show the same portion of space as seen through different forms of telescopes.
Justin Jonas, Rhodes University/HartRAO
Centaurus
Sixtyfoureyesfocussedonthesky MeerKAT
Location
90 km outside of a small Northern Cape town called Carnarvon, spread over an 8 km range of the Karoo, sit 64 interlinked radio telescopes. Like HartRAO, this quiet and isolated location is ideal to dodge the interference produced by electronics and also allows for a large area to be used, with space to expand.
The name MeerKAT comes from the Afrikaans word for ‘more’ and the original name, KAT. The telescope was renamed when it was expanded, and they could build ‘meer KAT’.
What does it do?
The ‘KAT’ in MeerKAT stands for Karoo Array Telescope, the original name of a smaller site. An array is a collection of similar things that are grouped together, which means that the Karoo Array Telescope is a bunch of smaller telescopes (or receivers) all working together to make one bigger, clearer picture. It scans for similar frequencies to HartRAO but can make much more detailed images. It is the most sensitive telescope of its type on the planet.
Pretoria
Cape Town
Carnarvon
Exciting Advances and Discoveries
MeerKAT, in its current form, has been running since 2018. It was built up over time and tested in less developed forms from around 2010.
Beyond taking some incredible and detailed pictures of remote objects in space, MeerKAT has produced images from the centre of our own Milky Way galaxy, which have led scientists to a lot of new questions and discoveries. There are plans for MeerKAT to become part of the Square Kilometer Array (SKA), a giant array telescope that is being built in two sections, in South Africa and Australia.
MeerKAT has provided incredibly high detail images of the remains of a supernova and the radio waves spinning off of it in ‘threads’. In 2024, MeerKAT produced an image that showed 49 new, previously unknown galaxies!
South Africa contributes to our understanding of the universe
Combined visible light and radio image of Pinwheel Galaxy M83, as observed by Palomar Observatory (pink) and MeerKAT (red). The radio image (red) shows the hydrogen clouds around the galaxy, that are invisible and can block optical telescopes from seeing past them.
Do you remember SkyMap from the last page? It’s an image of our galaxy, which was produced over many years by the HartRAO Radio Telescope.
MeerKAT was used to map the centre of our galaxy, and in just one month produced the most detailed image of it that we have! This was done with 64 telescopes working together as one.
SARAO, Heywood et al. (2022), J. C. Muñoz-Mateos
I. Heywood, SARAO
Palomar Observatory MeerKAT radio telescope
People in Astronomy Discovery through Collaboration and Teamwork
Gourab Lindsay Simpiwe
Dr Sinenhlanhla Sikhosana
Astrophysicist
Dr. Sinenhlanhla Sikhosana is an Astronomy lecturer at the University of KwaZulu-Natal. Her focus is in astrophysics, meaning she spends her time studying the stars! Sinenhlanhla grew up in the village of eXambu. She then attended the University of KwaZulu-Natal to achieve her dreams of becoming an astronomer. Sinenhlanhla has travelled all over the world as one of South Africa’s leading astronomers and has played an important role in understanding the stars!
Role
Dr Sinenhlanhla teaching a group of students.
Sinenhlanhla balances her time between learning about the stars and teaching students who also hope to be astronomers. This is very important as it means that the next generation of astronomers are in good hands!
Qualification and experience
Sinenhlanhla achieved her Doctorate degree in Astronomy and Astrophysics, making her an expert in stars and space! She studies data from South Africa’s own MeerKAT telescope to understand how our solar system has changed over billions of years! By learning about the stars, she is able to tell us more about our planet and the many other stars in our galaxy.
What great role- models! I can’t wait to follow in their footsteps!
Dr Sinenhlanhla Sikhosana
Radio Astronomy brings together some of the greatest minds in South Africa, and people with a great diversity of skills and expertise.
Research student
Science centre manager Workshop technician/machinist astrophysics
Vereese van Tonder
Software Engineer
Vereese van Tonder is a software engineer working at the South African Radio Astronomy Observatory (SARAO). She grew up in Namibia and spent her childhood looking at the stars, which would play a big role in her future. Vereese studied a Master’s Degree in Software Engineering at Stellenbosch University. This makes her very important when it comes to fixing and running South Africa’s telescopes!
Role
Vereese is mainly a problem solver! She has to understand new problems and then works closely with other members of her team to find creative ways to fix them. Vereese makes sure that South Africa’s telescopes are in good condition and running smoothly. She has to stay up to date with new ways to fix problems and improve our telescopes!
Qualification and experience
Not only does she have her Masters degree, but she is also completing her Doctorate degree. She is very prepared for fixing difficult problems that she may find when working on these telescopes. Vereese has also travelled to many different parts of the world doing what she loves! She has travelled to the USA, Germany and even Antarctica as part of her work building and fixing machines.
Maintaining cool equipment like this has its challenges!
