Spinning in Space: Upheavals since the Copernican Revolution – Fabian Schmidt
What do we know about the uniqueness of our planet – and what impact does that knowledge have?
The Copernican Revolution initiated a whole series of revolutions that redefined our place and our role in the universe. Until then, the Ptolemaic worldview had held sway in Europe, which claimed that the Earth is located at the centre of the universe while the sun, moon, and stars move around it. In the Copernican model, the Earth became one of six, then later one of nine planets that travel around the sun. Since the beginning of the twentieth century, we know that even the sun is only one of billions of suns in our Milky Way, and that ours is but one of billions of galaxies in the universe. But even as recently as 20 years ago we were not able to prove the existence of planets outside of our own solar system.
Over the past ten years, ground-breaking observations have enabled us to discover thousands of planets circling around other stars. Currently we can only observe these exoplanets indirectly using the tiny effect caused by the gravity of the planets on the movements of their respective suns. But direct observation of exoplanets will become possible within the next decade, allowing us to learn far more about them. The measurement of the atmosphere on these planets will be especially important, as it could provide clues to life in places other than on Earth.
The Earth has gone from being the centre of the universe to being a small planet among billions of planets
The planets that have so far been proven to exist within our immediate cosmic neighbourhood display great diversity in terms of size, composition, and temperature (see the recommended link). Dozens of them possess temperatures that would permit the existence of liquid water on their surface, thereby making them compatible with life. The number of these planets allows us to conclude that the majority of the billions of stars in our Milky Way are circled by a planetary system similar to the one around our sun. In a certain sense, this is nothing but a steady continuation of the Copernican Revolution: the Earth has gone from being the centre of the universe to being a small planet among billions of planets. Do these findings change our perception of ourselves as humans? Of course, even this latest development is not necessarily the end. We still know far too little about the actual conditions that exist on the surface of the exoplanets that resemble Earth. We have no idea whether life exists on any of these planets, and on how many of them. Learning more about the exoplanets could lead to many more upheavals for our worldview. What we do know for certain is that we will not be travelling to other planets in the foreseeable future. That’s why we need to do all we can to preserve the Earth as our only realistic environment. Fabian Schmidt is a physicist and researcher at the Max-Planck-Institute for Astrophysics in Garching. He joined the Junge Akademie in 2016.| Recommended Link: The following webpage from the University of Chicago provides a summary of the most complex exoplanet systems that have been proven to exist by the Kepler satellite. The page contains a visualisation of the relative size of the planets and their orbits. Note that the latter are not depicted at the same scale. The colour of the planets is arbitrary and has been selected for ease of illustration. |
