In recent years, thanks to state-of-the-art telescopes, astronomers around the world have discovered hundreds of other worlds located in distant star systems. But is it worth 100% to trust the method by which scientists find exoplanets in space?
Over the past several years, the Kepler telescope has been closely studying the stars, capturing small changes in the brightness of the celestial bodies. Such changes most often mean that a planet is flying between the star and the telescope, which is too small for the telescope to see it directly. Using this technique, astronomers have already managed to detect many planets far beyond the solar system.
Despite the fact that the Kepler telescope has qualitatively improved our understanding of distant space, not all of its forecasts should be trusted blindly and unconditionally. The article, recently published in the Astronomical Journal, analyzes the methods by which scientists determine a planet by changing the brightness of a star's glow. In the first few years of the telescope's operation, when astronomers were able to detect such an anomaly, the researchers racked their brains for quite some time trying to understand what exactly causes the periodic attenuation of the star. The fact is that, in addition to planets, there are quite large objects in space, which can also become a noticeable obstacle to the path of starlight. A striking example is clouds of interstellar matter of high density, a kind of "space dumps", the radius of which is sometimes huge, even on the scale of a star system.
However, as more and more potential planets were discovered, astronomers changed their strategy. Now everything is based on statistical probability: roughly speaking, any probability over 99% is considered to be “confirmed”. The new study notes that this technique has one significant drawback: it does not take into account the errors and possible errors of the telescope itself. And this can play a significant role: for example, the signals of tiny planets like Earth are so weak at large distances that it is almost impossible to distinguish them from an accidental glitch.
To illustrate their point of view, the authors analyze one exoplanet discovered by the Kepler telescope in 2015 - 452b. At that time, the planet was described as the "big brother" of the Earth, located in an orbit ideally suited for the emergence of conditions in which the usual life could develop. From a technical point of view, the discovery was flawless, and it was almost impossible to suspect the telescope of a mistake - however, in this case, too, the probability falls below 99% of the threshold, and the existence of the planet has not been conclusively confirmed. Taking into account all the side factors, the authors of the article argue that theoretically, in the case of such discoveries, only 9 out of 10 anomalies noticed by the telescope will actually be planets - in reality, this number may be even less. In the future, most astronomical discoveries will require revision - more powerful and accurate equipment (for example, the James Webb telescope) will help scientists establish the truth.
Vasily Makarov