Inspired by a comet
African astronomer Thebe Medupe’s journey into science.
Thebe Medupe grew up in a poor village outside Mmabatho, without electricity, lights or television, where he sat near the fire under the African sky, listening to the elders tell traditional Setswana stories. But his family sacrificed to send him to a high school in Mmabatho, where modern western science and mathematics captured his imagination. He went on to earn a doctorate in astrophysics at the University of Cape Town. Dr. Medupe stars in Cosmic Africa, a documentary film about traditional African astronomy released in 2003. He is a researcher at the South African Astronomical Observatory, currently studying the properties of variable stars. He is also participating in a programme to encourage black South Africans to take up astronomy.
Earth & Sky’s Jorge Salazar spoke with Thebe Medupe in May, 2006.
Salazar: What inspired you to become an astronomer?
Medupe: My interest in astronomy started when I was thirteen years old, when Halley’s comet became visible in southern Africa. Our school organized a theme around astronomy, and that really inspired me to want to know more about stars. I went to the library in our town and I read more about astronomy. I ended up finding a book on how to make a telescope out of material that you can easily find at home. And I built myself a telescope at that age. I’ve never looked down since that time.
What excites me about pulsating, or variable stars, is the prospect of using this variability, which is really due to the soundwaves generated in stars, and using these waves to probe the interior of stars. It?s like seismology, using the sounds from the stars to find out what stars are made out of. The light that we see from a star comes from a very shallow part of the star. But the sound waves that are generated inside stars can come from even the core of stars, and by analyzing these sound waves, we are able to get information from various depth points inside a star. So it?s a very powerful technique that allows you to reach a part of the star that otherwise we would not be able to because the light that you are receiving comes from the very shallow regions inside a the star.
We also have a group at the University of Cape Town that is interested in studying dark matter in the universe. These are things that you cannot see, but that we have evidence that they exist. And with the availability of the South African Large Telescope, we will be able to expand the kinds of studies that you can do with astronomy. For example, with the big telescope like SALT, a 10–meter plus telescope, we?ll be able to search for extrasolar planets, that is, planets that are orbiting stars other than the sun. Also, we?ll use it to study the universe during its early period of formation.
Salazar: How do you carry these pursuits, thinking about things like the insides of distant stars, or life on other planets, how does this affect your day–to–day life?
Medupe: Astrophysics, or astronomy, is a very amazing subject in the sense that it attempts to answer questions which most people have in their lives. Many of us want to know where do we come from, what will happen to us in the future, are we alone in the universe, questions like that. Until quite recently these things were considered to be quite philosophical. But today, astrophysics has allowed us to have scientific answers to these questions. Or at least attempt at scientific answers to those. For example, as to the question of where we come from, we know that we are children of stars. Without stars, there would be no elements that make us, elements like carbon, elements like nitrogen and oxygen, would not be there without the existence of stars.
As to whether we are alone in the universe, although we don?t have an answer to that question, it seems that planet formation in the universe is very common, because in the last 15 years, astronomers have discovered over 150 planets orbiting other stars. Although most of those planets are very large, like Jupiter, people are making attempts to look for planets that are similar to the Earth, and the idea is that at least one of those many, many Earth–like planets, if they are discovered in large amounts, that there will be a possibility of intelligent life, or just life, existing there.
And as to what will happen to us in the future, everything in the universe evolves. The same thing will happen to the sun. The sun was created 5 billion years ago. In another 5 billion years time, it will have used up all of its energy source. And the energy source right now is hydrogen being converted into helium by nuclear reactions happening there. Therefore, 5 billion years from now, the sun will be completely different from what it is today. It will swell up as it runs out of energy, it will cover the Earth and destroy any life that might still be existing on Earth. And so astronomy provides us with those mind–boggling answers that bother most people at one time or another in their lives.
Salazar: How do you know what’s true in the world?
Medupe: I?m science–orientated, and I put faith in the scientific method, the basic principle that if someone tells you that x and y exist, then that person must be able to prove to anyone who wants to know, either by detection or clear, physical evidence that such a thing exists. So for me, the method for finding the truth is predominantly a scientific one.
Salazar: Do you get that “evidence” from people, or books, newspapers, the internet?
Medupe: It?s a combination of all of those things. One is by reading a lot, and two is by relating what you are hearing with the techniques that you have learned as a scientist. Predominantly, in what I do, I combine what I see with modeling. Modeling a situation and then comparing that outcome of that model with what you see.
Salazar: What are some of the choices that you make in your life regarding living as a scientist?
Medupe: Ahh (laughs). The question that you are asking me reminds me of an experience that one of the famous astronomers, Carl Sagan, apparently had when he was shown the picture of the Earth taken by one of the explorers, on the way out of the solar system, just on the edge of the solar system. It looked like a little dot on the ocean of the whole universe. It really humbles you and makes you realize that you are just a tiny part of the whole cosmos. And for some people, it can have a very, almost religious experience, in the sense that some people use it to realize just how important unity is amongst humanity.
Salazar: Thank you for your time today, Dr. Medupe. Is there anything else you’d like to add?
Medupe: I would just like to say that astronomy is really thriving in South Africa. We are very lucky that the South African government has taken it up amongst themselves to sponsor research into astronomy, and we have very fantastic research facilities in South Africa. Astronomy is something that South Africa has been involved in for many, many thousands of years, and there is a lot of evidence to show that. I want to encourage anyone who wants to become an astronomer, because it is a very fulfilling career.
