About human curiosity and endless space
Since prehistoric times, people all around the world have been fascinated by space. Astronomy fills people with wonder, decorates the bedrooms of children and unsettles worldviews. Astronomical research doesn't just push the boundaries of knowledge; astronomers are searching for answers to the great questions of human existence. How big is the Universe? How did it come to exist? Where do we come from? And are we alone in space or is there life beyond Earth?
Is there life out there?
Is Earth unique? Astronomy is getting ever closer to answering this perhaps most fundamental question. The European Southern Observatory's Very Large Telescope and its gigantic instruments are already able to image the places where Earth-like planets could form. The James Webb Space Telescope combs through the infrared light emitted by these young disks of dust and gas and finds signatures of complex molecules that could act as building blocks of Earth-like planets and even life. The next revolution will be heralded by what will soon be the world's largest telescope in 2028, which will observe in both visible and infrared light. It could be the first telescope to detect life on extrasolar planets. The construction site of the Extremely Large Telescope (ELT) already gives an idea of the dimensions of the dome construction, comparable to the Colosseum in Rome.
Thanks to ever-improving instruments and constantly increasing data volumes, new aspects and nuances of the Universe are being revealed. However, each new insight generates new questions. For example, why the majority of the cosmos is made of dark matter and dark energy – about which we still know little today.
There have been many worldviews throughout human history in which the stars have played a central role. From symbol of the gods to scientific surveys: looking into the night sky has shaped the foundations of countless perspectives on our world. What role does astronomy have today – during times in which examining our home planet seems more urgent to some than looking into space? Each search for new worlds also tells a story about the uniqueness and fragility of our own planet. Data from astronomical research help us to understand climate change. Notably, astronomical research also shows us what can be achieved by large-scale international cooperation.
Over the last 100 years, our knowledge of the Universe has grown at an inconceivable rate. Researchers have powerful telescopes and space probes at their disposal, allowing them to glimpse into the depths of the universe. Supercomputers evaluate the resulting huge data volumes. In this way, cosmic phenomena can be researched with unprecedented accuracy. Highly complex computer models enable an increasingly intricate understanding of the emergence of the universe. Researchers are constantly gaining new insights into dark matter and dark energy, in spite of the fact that they have not yet been able to provide concrete proof of their existence.
Light as a universal information supplier
The philosophers of ancient times attempted to explain the world they saw before them. The invention of the telescope marked the beginning of a new era: in 1610, Galileo Galilei discovered four moons which orbit the planet Jupiter using simple means. Just a few hundred years later, international research collectives have erected large observatories on high mountains. For example, the Very Large Telescope (VLT) at the Paranal Observatory in Chile's Atacama desert, one of the most productive optical instruments in the world. It was here that a team led by Reinhard Genzel investigated the black hole at the center of our Milky Way, for which he received the Nobel Prize in Physics in 2020.
It isn't just visible light that plays an important role in astronomy; the universe is also illuminated by wavelengths that are invisible to the human eye. Researchers use the entire electromagnetic spectrum of radio waves right through to gamma rays in order to chart a comprehensive picture of the Universe.
Many eyes see more than two
Sometimes, even the biggest telescope is not capable of observing extremely distant or very special astronomical objects such as black holes. If matter or even light gets too close to a black hole, there is no escape. This is why obtaining an image of a black hole is technically impossible. Yet, this is exactly what radio astronomers managed to do as part of a global collaborative project. Connecting multiple radio telescopes on different continents with nanosecond precision allows them to create a virtual telescope with the diameter of the Earth – the Event Horizon Telescope (EHT). The Max Planck Institute for Radio Astronomy in Bonn is a partner in this project. At the Institute, huge sections of the enormous data volumes supplied by the telescope network are evaluated.
The world's first image of a black hole was published by the EHT collaboration in 2019. It showed a supermassive black hole at the center of the giant elliptical galaxy M87. In the meantime, they have also produced a "portrait photo" of Sagittarius A*, the black hole at the center of our Milky Way.
So close and yet so far – our home in space
For a long time, humans considered themselves to be at the center of the cosmos. However, our solar system actually occupies a rather modest position in the Universe. It sits in the Orion Arm of the Milky Way, our home galaxy, and orbits the center of the Milky Way at a distance of 25,000 to 28,000 light years. Inside our flat spiral galaxy alone there are hundreds of billions of stars, including our sun.
While we know a lot about our solar system today thanks to astronomical research, our immediate surroundings still present us with many riddles. Due to the relatively small distances – in astronomic terms – between objects inside it, our solar system can be explored with space probes. Equipped with cutting edge measuring instruments and camera systems, these uncrewed spacecraft transmit data to Earth, from which researchers can determine the composition of the atmosphere of a planet or the surface of an asteroid.
The probe Solar Orbiter, which was launched on February 10, 2020, is closer to the sun now than any probe which has come before it. For the first time, it will investigate the sun's poles. From this mission, the team led by Sami Solanki from the Max Planck Institute for Solar System Research hopes to glean decisive insights into solar winds and the emergence of the sun's magnetic field. Both have far-reaching consequences for the Earth.
The cosmos shakes
When large moving masses – such as two black holes – collide in space, this causes tremors in space-time, as Albert Einstein described in his theory of relativity, one hundred years ago. Einstein himself did not believe that humans could ever measure these gravitational waves, because the signals are too weak by the time they reach Earth.
In spite of Einstein's skepticism, on September 14, 2015, that’s just what happened: two large detectors in the United States had measured gravitational waves for the first time. The Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam and Hanover played a decisive role in the success. Here, vital components of the highly sensitive measuring equipment were developed and built. Using calculations and simulations, researchers at the Institute created the basis for recognizing the relevant signals in the flood of measurement data. Although cosmic catastrophes such as the collision of neutron stars release a gigantic amount of energy, the signals that eventually reach Earth become subtle vibrations in the noise of space.
For the first time, astronomers have at their disposal a type of information that is not dependent on electromagnetic radiation, i.e. light. This allows them new insights into the cosmos, potentially even into the initial short period of time directly following the Big Bang, as during this period the universe was not yet transparent to light.