550 years ago, Nicolaus Copernicus was born in the Hanseatic city of Thorn in Kulmerland, today’s Torun in Poland. Copernicus worked as a canon, doctor and economic thinker and also devoted his interest to astronomy. His main work “De revolutionibus orbium coelestium” (in English “About the orbits of the celestial spheres”) triggered the so-called Copernican revolution and still influences astronomy today, explains astronomer Dietrich Baade from the European Southern Observatory (ESO) research network in Garching.
SZ: Mr. Baade, with his description of the heliocentricity of our solar system in 1543, Nikolaus Copernicus turned the world view of his time upside down. What is the significance of Copernicus’ findings for today’s astronomy?
Dietrich Baade: The world view at that time was not scientific, but philosophical and assumed that the focus was on the human being. Copernicus cleared that up. So the Copernican revolution was actually even more important for non-scientists than for scientists – because it showed people their own smallness. This knowledge continued to grow: at the beginning of the 20th century it became clear that the sun is not in the center of the Milky Way but at its edge, and the Milky Way is not the center of the universe either. So we humans have been pushed further and further to the edge. Incidentally, Copernicus was not the first or the only one to assume heliocentrism. The Greek Aristarchus of Samos, for example, speaks of this in the third century BC. But it was only through Copernicus’ work that it was firmly anchored in the consciousness of mankind that the planets do not revolve around the earth, but around the sun.
People have been observing the sky and the celestial bodies for thousands of years. What is it about the stars that fascinates us so much?
When you show people an image of a spiral galaxy taken by the Hubble telescope, almost everyone agrees that it looks beautiful – why is that? We don’t know for sure. There is definitely something impressive about stargazing in a dark place on a clear night. There are also moving bodies – the sun, the moon and the ancient planets Mercury, Venus, Earth, Mars, Jupiter and Saturn, after which our seven days of the week are named. That already fascinated the Babylonians. At that time they tried to discover recurring patterns in the sky in order to be able to predict events on earth. However, such patterns do not exist. Overall, it’s probably people’s curiosity to want to describe things and want to know: what’s there? What’s behind it? And then to make use of this knowledge, think for example of the calendar.
The astronomer Dietrich Baade was deputy scientific director of ESO in Garching until 2016.
(Photo: ESO)
With today’s telescopes and instruments, researchers can see further into space than ever before.
Yes, astronomy is making incredible strides. Because astronomy does not conduct its own experiments, but instead observes what nature offers us, we are dependent on the technical advancement of our research instruments. With every new instrument we use, we discover new things. However, behind every new project there is not just one insight, but many. I would say that astronomy is one of the few fields of research where new territory is waiting around every other corner. Copernicus had to rely on much simpler instruments, so his groundbreaking and forever valid new approach is all the more admirable.
Which parts or aspects of the solar system are currently of particular scientific interest?
That depends on the tools available to researchers. On the one hand, the users of the ESO telescopes deal a lot with comets. These are bodies that come from very far away and have remained almost unchanged; From the material they are made of, one hopes to be able to draw conclusions about the formation of our solar system, which is almost five billion years old. In addition, our guest scientists research exoplanet systems, i.e. planets that orbit other stars or suns than ours. For this research one actually goes back to what Copernicus said. At the time of Copernicus, however, only one planetary system was known – ours. Today, thanks to the research findings of the past few years, we have opportunities for comparison. That means today we can start putting all the pieces of the puzzle together into one big picture.
The European Southern Observatory (ESO for short) claims to be the leading European organization for astronomical research. 16 countries have joined forces in ESO. ESO plans, builds and operates observatories with sophisticated research instruments designed to enable astronomers to make major scientific discoveries, including the Very Large Telescope (VLT) on Mount Paranal in Chile’s Atacama Desert. As the latest project, ESO is currently building the “Extremely Large Telescope” (ELT), which with a diameter of almost 39 meters will one day be the largest optical telescope in the world. ESO’s headquarters are in Garching near Munich.