Professor Thebe Medupe, a passionate astrophysicist, who wants to inspire African students to enter the world of astronomy and astrophysics.
By Gerrit Van Rooyen
In 1986 a cosmic event occurring every 75 years or so forever changed the life of one 13-year old boy from an impoverished village outside Mafikeng, a city in the North-West province of South Africa.
The cosmic event, visible in the night sky as a bright star with a tail, was Halley’s Comet, a large “dirty snowball” passing the earth on its orbit around the sun. The boy, Thebe Medupe, is now a professor in astronomy and astrophysics at North West University’s Mafikeng-campus.
In 2002 he obtained his PhD in astrophysics from the University of Cape Town (UCT) – becoming one of South Africa’s first black astronomers. “Right now we only have about 10 black astronomers in this country. After 20 years of democracy, it is shocking that this number hasn’t increased significantly,” says Medupe.
At the head quarters of the South African Astronomical Observatory in Cape Town, in a large office, with a wood floor and encircled by tall wooden book shelves, the short and stocky Medupe cheerfully recounts how his love for astronomy began.
“Fortunately my father and mother believed in education and did everything to send me to one of the best schools in town. That made my life easy and gave me as a 13-year-old boy the belief that I could be an astronomer.”
Medupe and his two brothers grew up in a house without electricity. Their father was a clerk and their mother stayed at home. Despite the hardship, he was sent to Mmbabatho High School, a multiracial, semi-private school and one of the best schools in town. “The school had very good mathematics teachers, computer labs and science labs.”
During the time that Halley’s Comet was visible in South Africa, his school had a whole week where all the subjects covered astronomy. “That triggered an interest in me. I went to the library almost every afternoon and read as much about astronomy as I could, even if I didn’t understand it!”
“The town had a really nice library with plenty of the latest books on various subjects.”From one of these library books he learned how to build a rudimentary telescope with cardboard and lenses. At night he would set up his telescope to gaze at the moon and the stars. This attracted attention from the other children in the neighbourhood, but young Thebe was very protective of his telescope and did not let anyone else near it.
“The other children in the village thought that I was crazy and weird,” Medupe chuckles.
In matric he entered a Science Olympiad and was the winner of his region. Consequently, he travelled to London where he visited Cambridge University and saw places Isaac Newton used to go. At Greenwich observatory he saw a working observatory for the first time. “This experience was a real eye-opener and only made me more determined to be a scientist.”
After lecturing at UCT for five years, Medupe decided to return to Mafikeng to try to get more African students involved in astronomy through the National Astrophysics and Space Science Programme (NASSP).
Medupe says that the Apartheid education system, which was completely Western and neglected anything African, gave the impression that Africans did not have a fascination with astronomy. “This doesn’t make sense, because everywhere else, in South America, Asia, Europe, and so on people have been inspired by the stars in exactly the same way.”
In 2002 Medupe was the presenter of the film Cosmic Africa, made by Craig and Damon Foster (makers of the award winning film The Great Dance). The film follows Medupe as he travels to different communities in Africa listening to their stories about the stars and sharing his scientific knowledge of the stars with them.
“My involvement in Cosmic Africa was a way for me to show how African people related to the stars. In that way I wanted to add a chapter to the world’s astronomy history by bringing Africa’s ancient astronomy to the public.
“If our ancestors were interested in astronomy there is no reason why astronomy should not form part of our African culture today.”
The Setswana, Medupe’s own culture, have many stories about the cosmos. According to the Setswana there is a big giant crocodile that eats the sun in the evening and spits it out in the morning. The Setswana have their own name for the stars we call the Southern Cross: the Giraffe stars, because the stars reminded them of the way giraffes move through the trees.
He spent a week with the Bushmen in Northern Namibia around the time of an eclipse. Bushmen are very afraid of an eclipse and believe it happens when a lion wraps its tail around the sun. The filmmakers wanted to see how the Bushmen would react to the eclipse – but they made a big mistake.
“The Bushmen were worried how we knew about the eclipse three days before it happened. They thought we were sorcerers of some kind that created the eclipse! We explained to them how we thought an eclipse is created and some of them understood it,” Medupe says.
“Meeting the Dogon people of Mali was like travelling 400 years back in time,” he says. “They pray to the stars in the morning when they wake up and also mention the stars in their prayers.”
The Dogon have a diviner who draws a map of the stars on the sand. When a jackal walks on this sand the diviner is said to be able to tell the future from the paw prints on the map.
They also visited stone alignments in Egypt dating back over 7000 years ago. That is a time before ancient Egypt, when the Sahara was not a desert but had seasonal rains. These stone alignments were like a stone calendar that used the sun to determine the solar solstices.
Medupe is also a founding director of Astronomy Africa, a company that combines tourism with astronomy training. “We go to game parks at night giving public talks to visitors and show them the stars through telescopes. It is quite fun to see places like the Kruger Park,” Medupe says. According to their website Astronomy Africa also do telescope installation and the construction of observatories.
Another project he worked on for five years was to analyse the Timbuktu manuscripts that contained writings on astronomy. Timbuktu, a town in the West African country of Mali, used to be a Mecca for trade and scholarship in the 15th and 16th centuries.
Hundreds of thousands of manuscripts, by Arab scholars from this time period and later, about subjects as diverse as astronomy, mathematics and biology have survived in the many libraries in the town. Medupe found two interesting books that described models of the solar system, which could accurately determine time and calendar.
A day in the live of an astrophysicist
Medupe typically heads to his office in Mafikeng at about 09:00 to start sifting through his research. He specializes in star variability, which involves using a branch of physics called fluid dynamics to determine the structure and composition of stars.
“Star variability is caused by waves travelling inside a star. The waves are not stable in a periodic way, but go up and down.” Stars emit different kind of waves. There are the visible wavelengths (the light you can see), there are shorter wavelengths, like x-ray and gamma-ray and there are longer wavelengths like infrared and radiowaves. Most of the radiation emitted from normal stars is in the visible wavelengths.
“Longer wavelengths are produced by cooler material such as gas and dust and shorter wavelengths are produced by very hot material.”
Medupe explains that the speed of soundwaves is also sensitive to the conditions through which the wave is travelling. “If we can somehow measure the speed of sound in a star we can reconstruct how the temperature, the pressure and the composition of the star changes in a star.
“It is a very powerful technique, because when you look at a star through a telescope you only see the very thin outer layer of a star. It is like seeing the skin of an apple and not being able to access the inside of the apple.”
Due to all the light and air pollution in the cities, most of the professional telescopes have been moved to a remote place outside Sutherland with a very a high altitude. Medupe often travels to the Southern African Large Telescope (SALT) outside Sutherland to do his research.
He travels a lot overseas as well to collaborate with scientist across the world. He spent one year of his doctoral studies in Denmark and has collaborated with Danish researchers on various projects ever since. He recently went back to Denmark for a month of research.
Why do you love astronomy so much?
“What I really like about astronomy is the questions it asks and how it tries to come up with answers for these questions.”One of these questions is:
‘Where do we come from?’ “The answer is beautiful,” Medupe says.
“When you take a sample of my skin and analyse it you will find carbon, hydrogen, oxygen and nitrogen. Except for hydrogen, which was created during the Big Bang all the other chemicals were created in the hearts of stars. Really we are stars’ children. Without stars we would not be.”
The other question is: ‘What will happen to us?’ “Five billion years from now the sun will run out of hydrogen in its centre and it will swell up and engulf the earth. If humans beings do not by then know how to live in other parts outside our solar system, we will be doomed.”
Are we alone? Medupe thinks we are probably not alone. “I’m motivated in saying that, because in the last six years astronomers have discovered more than a thousand planets around other stars. I cannot believe that the Earth is the only planet of its kind in the universe. There is a good possibility that there are living things out there.
What is cutting edge in astronomy?
“The most exciting development in the last 5 years has been Mars,” he says. Five years ago the European space commission detected methane gas in the atmosphere of mars. “On earth methane gas is usually emitted by animals or volcanoes,” Medupe explains. The question is now whether Mars is volcanically active or if it is not, whether living things could have created the methane. “There is a possibility of life beneath the soil of Mars.”
The nature of dark matter is another hot topic in astronomy at the moment, according to Medupe. “The matter we can see in the universe only accounts for 4% of the entire universe. We know the dark matter is there because of its effect on other things, but we want to know what form dark matter takes.
“Is it exotic particles? That is particles that are sensitive to gravity but somehow invisible.
“Or is it just a lot of dead stars? Or could it be that the laws of physics are not the same across the universe? That they change depending on how far you look in the universe?”
Is it difficult to become an astronomer?
Medupe says to become a professional astronomer or astrophysicist you must have a PhD and you have to be trained in computer programming.
“If you love it, it is not hard work at all!
“I love what I do. Even if I were to lose my job I would still do astronomy in my spare time. I feel very lucky that I get paid to do something I consider a hobby.”