If aliens were looking for us, then it was much easier for them in the Jurassic period.

Several years ago, Michael and his observatory colleagues discovered a very distant planet, whose location and atmospheric composition made it suitable for life. They needed more information, so they decided to launch a ship with a rover to this planet, which they called the Blue Marble. Now they’re celebrating the successful landing and the rover’s first images being downloaded to their computer. They hold their breath and suddenly see in horror how the screen is filled with the image of huge animals with feathered bodies and ferocious appearance, shaking the surface of the planet with their heavy steps, on which the rover barely remains. All this may seem like the plot of a futuristic movie, but in fact this is exactly what would happen if an extraterrestrial civilization found Earth earlier. 100 million years.

In May 1999, Project SETI was launched to search for radio signals that were likely sent from other planets. In 1995, astrophysicists Didier Queloz and Michel Mayor first discovered exoplanet. This opened up enormous scope for the search for new worlds. Gradually, a number of methods have been refined that allow us to calculate the likelihood that a planet is habitable. we still can’t find life. What would happen if we did the opposite? Could there be intelligent beings on other worlds who are looking for extraterrestrial life and cannot find us?

It is quite possible that yes. After all, it would be quite self-centered to think that we are alone in Universe. The problem is that the Universe is huge and the search is difficult for both some and others. Therefore, a group of scientists from Cornell University conducted a study aimed at testing when it would be easier to find us from an extraterrestrial planet. And the results are very interesting, because it turns out that finding the Earth when people still inhabited it was much easier. dinosaurs.

A simple but challenging search for extraterrestrial life

Once an exoplanet is discovered, it is important to take two factors into account to determine whether it is inhabited. On the one hand, it must be in the habitable zone of its star. That is, neither too close for the water to evaporate, nor too far for it to freeze.

In addition, it must have an atmosphere that protects its surface from cosmic radiation, and the said atmosphere must contain gases necessary for life. The latter is analyzed spectrum measurement. That is, he studies how light entering the planet is blocked. Depending on the gases in it, certain wavelengths will be blocked, so the spectrum formed by unblocked light can give information about what kind of gases they are.

It is logical that the fact that these gases are found in the habitable zone does not mean that life exists on the planet in complete safety. To study the scenario more thoroughly, you will have to send probes or robots, as the alien Michael did. Although not everything is so simple, because logically, the first paragraph of this article is nothing more than a simplified dramatization.

Now, if we can measure the spectra of another planet, couldn’t they measure our own from a distant location? alien planet? There is no reason to think not.

Habitability that goes unnoticed

Earth scientists at Cornell University wanted to know how we have been seen from space over the past few million years.

In particular, they focused on the period known as Phanerozoicwhich started a few years ago 542 million years and continues today. Its translation is “visible life” because it corresponds to the years in which the Earth was inhabited by non-microscopic life.

This life, in turn, is responsible for the composition of the atmosphere. The composition, which has changed little by little throughout this time. Today we have changing of the climate caused by humans as the main reason for the change in said composition, but there were other modifications caused by other causes that, although equally habitable, would result in a completely different spectral profile if aliens were to explore us.

Using climate models and fossil data, they were able to calculate the spectral characteristics of the atmosphere. every 100 years. Oxygen levels varied throughout the Phanerozoic. from 15% to 30%. Both limits border on the extremes of 13%, at which fire would be impossible to ignite, and 35%, at which matter would burn so quickly that it would be impossible to grow forests. We are currently in a healthy twenty one%. Great, of course, from an oxygen point of view. We leave greenhouse gas levels for many other articles.

Age of dinosaurs

He thirty% This exactly corresponds to the years when the Earth was inhabited by dinosaurs. This is a very high percentage of oxygen, but it is also accompanied by other gases that, if we saw them on an extraterrestrial planet, would be a very good indicator of life.

In particular, this study showed that spectral signatures consisting mainly of oxygen and methane or ozone and methane These are the ones who would be easiest to connect with life. And these prevailed back 100-300 million years, especially during the time of the dinosaurs.

Therefore, if the alien Michael and his companions existed, perhaps they would collide with us. But perhaps they stumbled upon a planet full of merciless beasts and decided to take their ships somewhere else. That would be the smartest thing to do, there’s no doubt about it.