In less than a year, NASA’s James Webb telescope has already yielded a slew of discoveries. This week, for example, he proved the existence of an Earth-like planet. ‘The euphoria is certainly not exaggerated,’ says Belgian astrophysicist Leen Decin (KU Leuven).
The Webb Telescope is currently the star of the Seattle International Space Congress. What makes him so special?
“In the first place are technical capabilities. For example, there is the size of the mirror, which with its 6.5 meter diameter is the largest ever in space. This ensures that it can observe much more sensitively than its predecessor, the Hubble Space Telescope. When the Webb telescope launched at the end of 2021, its mirror had to be fully folded in the launch vehicle. In space, it then had to unfold carefully and be perfectly aligned, as well as being cooled. An amazing piece of technology.”
“Behind that mirror are also a number of impressive instruments that make observations. The Hubble mainly looked into the optical light, the light that we can also see with our own eyes. The James Webb looks into infrared light, similar to the wavelengths of your microwave oven. That difference is huge. You cannot see through an interstellar cloud of gas and dust particles with optical light, but you can with infrared light. As a result, we can now suddenly see a lot of things that have remained invisible until now.”
The Webb telescope this week provided the first evidence of some kind of Earth-like planet. Why is that a breakthrough?
“We already know Earth-like, rocky planets outside our Earth. But with the Webb telescope we can now also take a closer look at them to see what kind of atmosphere they have. So it is not about the discovery of a new planet, but about a more accurate observation.”
“If you look at a planet flying around another star, such a planet is really miniscule. The best time to observe it is during the ‘transit’, the moment when the planet is exactly between you and the star. Like a fruit fly that flies just in front of your headlight: suddenly a tiny bit of light is lost and you notice that something is hanging in front of your lamp. The James Webb telescope has now proven to be sensitive enough to observe the transit of such a very small, Earth-like planet. That opens the door for many more observations in the future.”
At the launch of the telescope, observers spoke of an “Apollo moment” and “the hope of a new generation of astronomers.” Is that euphoria justified?
“Yes, she is certainly not exaggerated. The telescope really revolutionizes astrophysics. Suddenly we have data that we have long hoped for, because it holds the key to a number of crucial astrophysical questions. It is also logical to speak of a generation. My first meetings about the James Webb telescope date back to the late 1990s. It takes 25 years for a rocket launch like this to happen. People have been working on this their entire career.”
What exciting discoveries can we expect in the coming years?
“First and foremost, there is the search for extraterrestrial life. With the Webb telescope we can determine the weather climates and the chemical composition of planets. For example, we can look for ‘fingerprints’ of certain chemical processes that could originate from biological activity. Indirect indications of extraterrestrial life, so to speak.”
“The second is a new look at the big bang. Our universe is 13.8 billion years old, but we still don’t really know what happened in those first 300 million years. We do know that stars and galaxies formed, but not how. With the Webb telescope, we can now really pierce into the interstellar center, which will hopefully help us better understand the big bang.”