What if the aliens discovered us first?

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Can humanity be detected by possible alien civilizations?

The invasion of an evil alien species, or its counterpart, the more or less enigmatic visit of peaceful creatures, are recurring themes of science fiction. Each time a question arises: how could they find us in the vastness of a galaxy made up of one hundred billion stars?

E. T. Do you listen to the radio?

The first answer that comes to mind is of course our radio waves. After all, we have been transmitting for over a hundred years in all directions, and those transmissions must have come a long way at the speed of light. But it’s not that simple.

First, some frequencies will not even pass through the atmosphere, diverted by their upper layers. Those who arrive in space will not allow us to discover the best and the worst of our musical creation with years of discrepancy, as proposed by the lightyear web. fm in a playful way. The further away you go, the more power a radio signal will lose (in reverse order to the square of the distance). In short, after only a few light years, the Top 50 will no longer differ from the radio background noise present in space.

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When we consider sending radio messages to potential extraterrestrial civilizations, they are very powerful signals aimed at a specific point in the sky, not our daily broadcasts. But you have to be sure that there will be someone at the other end to receive the transmission.

9 exoplanets that can see the Earth

To be interested in our little planet, you have to know it exists. Detecting it with telescopes is not easy: it is small, it has much more massive companions (Jupiter, Saturn…). The safest way would be to see it pass directly in front of the Sun, which is called transit. But for this to happen, the observer must be in a very specific area, where the Earth would pass between the Sun and him. Too high or too low, and it’s a failure.
With this method of transits, the Earth would paradoxically have an advantage over the giant planets of our solar system: it passes in front of the Sun once a year, compared to just over 12 for Jupiter and 29 for Saturn.

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Scientists from the University of Queen’s in Belfast (Northern Ireland) and the Max Planck Institute for Solar System Research (Germany) have recently studied areas of the galaxy that could potentially be observed by the planetary transits of our solar system, and have published their findings in the journal Monthly Notices of the Royal Astronomical Society.

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Of the total of about 4,000 exo planet known, the team was able to identify 68 worlds from which an observer could see a planet around the Sun. Of these 68.9 are “ideally placed to observe Earth’s transits,”say these scientists. Unfortunately, none of them are located in a habitable area, which means that liquid water cannot exist on its surface.

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There is still one small hope: the team thinks there would be a dozen worlds, which we have not yet discovered, capable of welcoming life as we know it and which would be in a favorable place for the detection of the Earth.

Even for those with the correct viewing angle, it is not cooked at all. “We estimate that a randomly placed observer would have a chance in 40 to observe at least one planet (of our solar system),” explains Katja Poppenhaeger, co-author of the study. “The probability of detecting at least two planets would be ten times less, and the probability of detecting three planets would be ten times less.”

A planet modified by humans

>A planet modified by humans

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Knowing Earth is here isn’t going to inform E. T. to its inhabitants. You will know that there is a planet, you will know its size and even its mass, and you will see that it is in the “habitable zone”, but this is all that traffic can only bring you. To learn more, you’ll have to look for other clues.

A team of researchers has begun to catalogue the different elements of the present and past terrestrial biosphere that could represent “signs of life”. If current space telescopes, such as Képler and Hubble, do not have the capability to detect such signals, future generations will not be able to do so, starting with TESS and the James Webb Space Telescope, scheduled to be launched in 2018.

The presence of a civilization on Earth could be detected in the same way, depending on the components present or not in its atmosphere.

But that’s not all: an international team led by Adam Franck from the University of Rochester (USA) has just defined a possible classification of rocky planets, described in a study published in the journal Anthropocene.

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Five kinds of exoplanets

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“What we have recognised in our classification is that we cannot use energy without generating different types of waste. This garbage is a return to the state of the planet,”says Adam Franck. The various signs that have been used to determine the planet’s entry into a new era, that of humanity or anthropocene, can then become indicators of the existence of a civilization and the stage in which it finds itself.

This classification has five levels or classes:

Class I are planets without atmosphere, such as Mercury or the Moon.
Class II is represented by planets with atmosphere but without life, such as Venus or Mars.

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Class III, which does not exist today in the solar system, would be that of the planets where life appeared, but where it has not yet completely affected its environment. An example would be Earth before life brought large amounts of oxygen into its atmosphere.

Class IV includes planets with a thick biosphere that affects the entire planet, such as Earth.

Class V would be that of a planet where technology has been integrated into the biosphere in a “sustainable cooperation”. On such a planet, civilization, for example, would have allowed deserts to become greener, found a way to absorb the carbon dioxide that causes global warming, or created genetically modified trees that would convert solar energy into electricity.

Earth, the hybrid planet?

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According to the authors, today’s Earth would be in a hybrid state between class IV and class V.”We assume that the entry of the Earth into anthropocene represents what, from an astrobiological perspective, would be a predictable planetary transition,”they explain. “The beginning of anthropocene could be seen as the beginning of the hybridization of the planet, an intermediate stage between one class and the other.”

In this optimistic perspective, the damage caused by civilization would only be a step towards a sustainable civilization that would maintain the planet’s good health.

Such technological “supercivilization” would also be remotely detectable for those who recognize its signs, but we are not there yet. Potential extraterrestrial observers analyzing Earth data would see us as a planet in transition, with possibilities of evolution for the better… or worse?

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Putting oneself in the shoes of aliens

Understand how the signs of life and civilization on Earth can be detected by a possible alien civilization may seem of little practical interest, except as a vision of the mind. However, this is not the case.

If we had already detected other planets harboring life, or if we had several examples in the solar system, the task would undoubtedly be easier, but today, the only trace of life and civilization in the universe is our good old planet.

To understand how a hypothetical professor E. T. T. could detect us remotely today is telling us, reversing the problem, what we will be able to see when we look more closely at other solar systems, with more data.

To understand how a hypothetical professor E. T. T. could detect us remotely today is telling us, reversing the problem, what we will be able to see when we look more closely at other solar systems, with more data. <.

In the absence of a point of comparison, we can only search with certainty for planets similar to ours. So when we get some data from an exoplanet, near or far away, we can know that we have found life elsewhere….

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https://www.theguardian.com/science/2017/sep/01/alien-search-detects-radio-signals-from-dwarf-galaxy-3bn-light-years-from-earth

http://www.independent.co.uk/life-style/gadgets-and-tech/news/fast-radio-bursts-frbs-breakthrough-extraterrestrial-message-signal-alien-hunters-galaxy-a7921671.html DIFUNDE LA PALABRA-