Webb telescope detects "prebiotic molecules"! Is there really alien life?

Produced by: Science Popularization China

Author: Xie Jiwei (Nanjing University)

Producer: China Science Expo

Recently, NASA announced that the James Webb Space Telescope has revealed a surprising molecule hidden in the icy clouds of the cold, dark universe. As soon as the news came out, science fiction fans couldn't sit still. Could there really be alien life? Don't worry! Today, we're going to talk about this "prebiotic molecule".

This image, taken by the Webb telescope's near-infrared camera, depicts the central region of the Chamaeleon I molecular cloud. Image credit: NASA/ESA/Canadian Space Agency

Does extraterrestrial life really exist?

"Is there life outside the Earth?", "Are humans alone in the universe?" These are interesting but fundamental questions. Students of all ages are often very curious about these questions, and scientists also often think about such questions. Reasoning from both scientific and historical perspectives, extraterrestrial life does exist, and humans are not alone in the universe.

From a scientific point of view, the vastness of the universe is almost beyond our imagination. There are at least 100 billion stars in our Milky Way galaxy, and at least 100 billion galaxies in the entire universe. Although the probability of a planet with life around a star is very low, a very small number multiplied by a very large number is unlikely to equal only 1 (that is, our Earth). In other words, there is a high probability that there are planets with life like Earth in the universe.

From a historical perspective, "Are humans alone?" is not a new question. Hundreds of thousands of years ago, ancient people began to wonder whether there were people like them in the far reaches of the world. So they found different ethnic groups, formed tribes and countries. More than 500 years ago, Columbus and other navigators were curious whether there were people like them on the other side of the ocean, so they discovered the New World, formed globalization and the human community.

Now, we are still curious about the same question - are humans alone? However, this time we are facing space, the vast universe. I believe history will still give the same answer.

Although I believe in the existence of extraterrestrial life, it is not easy to discover or even contact them. Humans still have a long way to go. The discovery of "prebiotic molecules" detected by the Webb telescope is just a small step in the long journey of exploring extraterrestrial life. It further scientifically supports the belief that "extraterrestrial life exists" and "humans are not alone in the universe."

James Webb Space Telescope observes the infrared spectrum of the Chamaeleon I molecular cloud

Various spectral line features in the spectrum reveal the presence of various molecules

ILLUSTRATION: NASA, ESA, CSA, Joseph Olmsted (STScI)

SCIENCE: Klaus Pontoppidan (STScI), Nicolas M. Crouzet (LEI), Zak Smith (The Open University), Melissa McClure (Leiden Observatory)

What exactly are “prebiotic molecules”?

"Prebiotic molecules" are actually simple molecules that generally existed before the origin of life, such as water, carbon monoxide, carbon dioxide, ammonia, methane, methanol, etc. Its discovery does not mean that humans have found extraterrestrial life. In fact, some so-called prebiotic molecules have been discovered before, such as in the atmospheres of some exoplanets and around some young stars.

However, the molecules observed this time rely on the powerful detection capabilities of the Webb telescope, which exists in extremely dense and cold molecular clouds. And because the Webb telescope has a very wide spectral coverage, it can detect many molecular spectral lines at the same time.

This study is the most comprehensive observation of the composition of ice before the formation of these stars and planets. The scientific significance of this study is that it reveals that these so-called prebiotic molecules (water, carbon monoxide, carbon dioxide and some organic molecules such as methanol) have been formed deep in the ice of molecular clouds long before the birth of stars and planets.

Webb Telescope - the best choice for observation

As the most powerful infrared space telescope ever, the Webb telescope can make unprecedented discoveries in all astronomical fields, from the universe to the planets.

It can see very far, it can see the first stars and galaxies formed after the birth of the universe, giving us a new understanding of the birth of the universe, the formation and evolution of galaxies. It can also see very "detailed", in addition to discovering various ice molecules in molecular clouds that permeate the universe, it can also detect the composition of the atmosphere of planets outside the solar system, greatly expanding our understanding of planets, including the earth, and the origin of life.

James Webb Space Telescope

Image source: Veer Gallery

The Webb telescope is a well-deserved "behind-the-scenes hero" for this discovery. The basic principle of discovering these molecules is that the light from background stars passes through the molecular cloud and is observed by the telescope's spectrometer. Various ice molecules in the molecular cloud usually absorb photons of specific wavelengths, leaving a mark on the spectrum, namely the spectral absorption line, which is detected and discovered.

Many molecular spectral lines fall in the infrared band, which is the main band of the Webb telescope. The objects of observation this time are two dense molecular clouds, so the signal reaching the telescope after the light passes through is very weak, and a large telescope (with strong light-gathering ability) such as the Webb telescope is required to detect it.

Can other astronomical telescopes observe it? The answer is basically no. First of all, in order to eliminate the influence of various molecules in the earth's atmosphere (water, carbon dioxide and other molecules), ground-based telescopes cannot be used. As for space telescopes, although Hubble's observation capabilities are also very strong, its operating band is mainly in the optical and near-infrared bands, and it is powerless in the mid-infrared and far-infrared bands.

Therefore, the Webb telescope is currently the most ideal astronomical telescope in this regard. Its aperture is larger than Hubble's, its light-gathering ability is stronger, it can detect fainter signals, and its operating band covers a wide range in the infrared band, which can detect a large number of molecular spectral lines.

James Webb Space Telescope Observes Star-Filled Pillars of Creation

Image source: Veer Gallery

Conclusion

This research is part of the Ice Age project, one of 13 early release science projects for the Webb telescope. These observations are designed to demonstrate Webb's observing capabilities and allow astronomers to learn how to get the most out of the instrument.

It is expected that the Webb telescope will carry out further observations in the future to help us understand how ice evolves from its initial synthesis to the comet formation region of the protoplanetary disk, thereby revealing important scientific issues such as which mixture of ices (which elements) can eventually be delivered to the surface of terrestrial planets or integrated into the atmospheres of giant planets.

This discovery does not mean that extraterrestrial life has been found, but it can be regarded as another step in the search for extraterrestrial life. It reveals that these so-called prebiotic molecules were formed deep in the ice of molecular clouds long before the birth of stars and planets. Considering that molecular clouds are everywhere in the universe, the results of this study also mean that the origin of life has similar initial conditions everywhere in the universe.

This discovery scientifically supports the belief that "extraterrestrial life exists" and "human beings are not alone in the universe." It is precisely this belief that has prompted humans to explore the universe tirelessly and constantly turn "beliefs" into "common sense."

Editor: Ying Yike