Exoplanets like Earth? 3 pitfalls to avoid

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those in the “habitable zone,” called TOI-700e, It was revealed via the TESS satellite (Transiting an exoplanet survey satellite ). other, LHS-475 b, is the first rocky exoplanet whose existence has been confirmed by the James Webb Telescope (we suspect its existence thanks to data from TESS). This indicates that there will be other discoveries of this kind.

gold, As explained before Rumor detector From 2017 In a previous discovery, whenever this type of announcement occurs, those who immediately imagine extraterrestrial life should beware of three pitfalls.

Mistake #1: “Livable area” doesn’t mean habitable

In 2017, a NASA press conference announced with great fanfare the discovery of seven planets around the same star (TRAPPIST-1), three of which are in the “habitable zone”, and “life forms” have not yet ended. “Dominate the exchanges. However, the problem with expression is.” Residential area It is that around the Sun, Venus and Mars are also in the “habitable zone”. So there are other criteria to consider:

• Is there atmosphere? Although the discovery of the first exoplanet – or a planet orbiting a star other than our sun – dates back to the 1990s, it wasn’t until 2016 that, for the first time, Astronomers have determined the atmosphere around this planet. This kind of detection is starting to come within the reach of instruments, and of the telescopes launched in this search, only James Webb (JW) will theoretically be able to go so far as to identify some of the components of these atmospheres.
• What does it contain? However, the existence of an atmosphere does not mean that there is life. For example, one of Saturn’s moons, Titan, is surrounded by a thick atmosphere of nitrogen and methane, which is an inhospitable mixture.
• Is there any water? Water is the ideal ingredient for synthesizing the molecules that make up the “building blocks” of life, and it must remain in a liquid state, i.e. a temperature between 0 and 100 degrees Celsius. Theoretically, analyzing the atmosphere – if it exists – of these planets would make it possible to detect water vapor there, which would be a great moment for astronomy. Right now, we don’t know what’s going on with the new exoplanets, LHS-475 b and TOI-700e. They are part of a short list of candidates who will receive special attention from JW in the coming months and years.

Pitfall #2: Disclosure does not mean imaging

Since the first announcement of an exoplanet, more than 5,200 have been confirmed, and 9,000 “candidates” await confirmation. But in the vast majority of cases, the disclosure is indirect: only About thirty planets are depicted -And also, Pictures show, at best, point a few pixels. The images of these planets that can be seen almost everywhere are systematically artistic representations. Everything we know about them – mass, volume, temperature, and so on. It comes from indirect measurements or deductions.

Indirect detection can be done in two ways. On the other hand, the natural oscillations From the star it can betray that a more or less massive “body” is spinning around it, “pulling” it sometimes to one side, sometimes to the other. On the other hand, prof decrease in brightness The star can betray that something has passed between us and him – that is The so-called “transit” method These are subtle differences, from which it is still difficult to tell when a planet is as young as Earth.

Trap #3: “Earth-like” does not mean…Earth-like!

When the search for exoplanets, or planets outside our solar system, laid its first prey nearly 30 years ago, they were giant planets, even very giant planets: many were more than 10 times the size of Jupiter—which alone could contain more than from a thousand earth. term “Earth-like planet” (Earth-like planet) was thus more of a distant aspiration than a true definition: the hope that technology would one day make it possible to discover “rocky” planets (such as Venus, Earth, and Mars). Now that astronomers are well and truly out there, attention is turning to the clues that distinguish Earth from its rocky fellows: the atmosphere, and especially the water.

Image: Artist’s rendering of LHS-475 b and its star/ESA/NASA