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Extraterrestrial life: similar to us and closer than we thought

A significant number of red dwarf stars (which make up most of the stars around us) have planets similar to Earth. It turns out that they are much more friendly to life than previously thought

red dwarf From Wikipedia
red dwarf From Wikipedia

In a review article published these days in the International Journal of Astrobiology Yosef Gil and Emri Wandel (Gale, Wandel) from the Hebrew University in Jerusalem show that the most likely place to find life outside the solar system is probably in the planets surrounding small dim suns of the type that astronomers call "red dwarfs", to which most (up to 90%) of the stars around us belong.

Findings published in recent years by NASA's Kepler space telescope, whose main mission is to find planets similar to Earth, and in particular the statistics of planets discovered by Kepler around red dwarfs, show that a large part (up to 40%) Of these stars there is at least one planet similar to Earth in terms of size and temperature. The authors combine these data with recent calculations that show that there is no obstacle to the development of life similar to those that developed on Earth on planets surrounding red dwarfs, contrary to what was commonly thought until a few years ago. In particular, the authors show that such planets have suitable conditions for photosynthesis, which is considered essential for the existence of most forms of life on Earth, and therefore life of the type we know on Earth is apparently much more common outside the solar system than previously thought.

Winds and radiation: The red dwarf isn't so bad

Since red dwarfs shine much less than stars similar to our Sun, their "habitable zone" (where liquid water may exist on the surface of a planet) is much smaller than that of the Solar System. In other words, for the temperature on the surface of a red dwarf solar planet to be high enough for liquid water to exist, it must be very close to the Sun. Until recently, it was commonly assumed that the conditions on planets near red dwarfs were unsuitable for life, for a number of reasons.

First, the planets closest to their sun will be "tidally locked", that is, always facing the same side to the sun, like Mercury in our solar system, or the moon always facing the same side to the earth. The side facing the sun will be very hot and the other side - very cold. In the past, scientists thought that such a temperature distribution would cause strong winds between the two sides of the locked planets, resulting in a turbulent climate that would hinder the development of life. Simulations of the atmosphere and climate on such a planet have shown that the winds are much milder than they thought.

Second, it was commonly thought that life could not develop and exist on exoplanets near red dwarfs because of bursts of ultraviolet and X-rays, common during the early development of red dwarfs. It is speculated that these eruptions can harm life and even vaporize the atmospheres of nearby planets. However, mature red dwarfs are quieter. In addition, calculations made in recent years show that a massive atmosphere of a large enough planet can survive the eruptions during the early development period, and alternatively a new atmosphere can be formed in the planets during the more relaxed maturation period of the red dwarf.

Photosynthesis: just like at home

For many years, the astrobiology community believed that if life exists on red dwarf planets, it must be based on a different photosynthesis mechanism than on Earth, since red dwarfs are less hot than stars similar to the Sun, and therefore the radiation from them is less energetic and concentrated mainly in the infrared region, which does not contribute for photosynthesis in the plants of the earth. This claim is disproved in the present article, which shows that although most of the energy in the spectrum characteristic of red dwarfs is in the infrared, there is still enough energy in the visible light range for photosynthesis in the mechanism that exists on Earth. So there is no need for a different mechanism of photosynthesis. Furthermore, the continuous radiation regime on a "locked" red dwarf planet may be similar to that common at high latitudes on Earth during the short summer periods, when summer vegetation thrives in northern countries.

Extraterrestrial life - closer than we thought

The conclusion of the article is that the conditions on the planets surrounding red dwarfs may be suitable for photosynthesis just like the one that occurs on Earth, where it is an essential factor in the development of complex life. Furthermore, since most of the stars around us are red dwarfs, which have a much longer lifespan than stars similar to the Sun, it is statistically more likely to find life outside our solar system on red dwarf planets than on planets orbiting stars of a type similar to our Sun. as was commonly thought until now.
From the distance estimate presented in a previous article by Wendel (see “The Kepler data increase the likelihood of a widespread distribution of life in the universe", the scientist 2014)
We find that our closest neighbor with life, perhaps even life similar to that which has evolved on Earth, is likely to be a planet orbiting a small red sun, about 10 light years from Earth. It is possible that this assessment could already be tested using advanced telescopes such as JWST and TMT which are planned to start operating in the next decade.
The full article

More of the topic in Hayadan:


20 תגובות

  1. WD and miracles:
    As I said, it will be very difficult to assess to what level they managed to develop their technology, since it will be based on science that we have not yet been able to discover. But we can appreciate the lower level of their science and technology, which is actually our science and technology, plus more future developments that have not yet been put into practice.
    Since we are today technologically able to scan the sky and find planets that could theoretically support life, we can appreciate that this is not a complicated act for a more advanced culture. It can be estimated that their satellites and telescopes are much more advanced than ours, and they have already mapped most of the stars that can be discovered from their relative positions, their planets, including which planets are capable of supporting life, at distances that allow the discovery of an atmosphere.
    In the scenario I described, which is actually related to what was said above, I did not mean messages that are directed specifically in the direction of DHA, but rather a kind of general message towards technologically advanced cultures, in a form of communication that we still do not understand, in the hope that a certain culture will pick it up. This is in contrast to Seti's efforts to use radio communication, which is ineffective at interstellar distances.

  2. Miracles

    I may have misunderstood the scenario that my father describes but I thought that when he says that they already discovered us a long time ago after he talked about how they technologically implemented all our wildest ideas, he means that they are aware of what is going on here. After all, our wildest ideas include quite a few things that will allow them to do so relatively easily.

  3. WD
    How can an alien culture know what technology we have? If we discover life on a distant planet, we will know very little about it without visiting it.

  4. Avi Cohen

    If they discovered us a long time ago, it is not improbable that at the time they discovered us there was nothing interesting here for them (which could very well be true even today).

    Why would they send us messages that we don't have the appropriate technology to receive them?
    If they are as advanced as you describe, they should know that we do not have the capabilities to receive these messages, therefore if they want to send us messages that they are interested in receiving, it is likely that they will use means that we are able to receive.

  5. Why settle for just charts and pictures? Maybe a more developed culture can send us virtual reality movies of their world similar to the movie Contact...
    In any case, if there are more advanced civilizations, their technology should appear to us as "works of magic", so that even the wildest ideas we have come up with here, they have already implemented in practice. Because of this, it will be difficult for us to assess what their capabilities are. But one thing seems clear to me, that as soon as a civilization becomes interstellar, it abandons radio wave technology for communication, because it is not effective at interstellar distances.
    In addition to this, if at our technological stage, we manage to develop tools that allow us to find and identify life-supporting worlds, then it is likely that the advanced civilizations, if they exist, have already discovered us a long time ago.
    They may even be sending us messages right now, but we don't yet have the appropriate technology to receive them.

  6. Totally agree, intelligent life is probably much rarer in the universe, and those that have already developed advanced technology have probably either destroyed themselves or stopped broadcasting to the outside.

  7. If we take the only example of the development of life known to us, life on Earth, the most primitive form of life we ​​will encounter on other planets will probably be single-celled in the oceans, since this has been the case on Earth for 3 billion years out of 3.8 billion in which there is evidence of life. Intelligent life and technological civilizations, if they exist, are probably much rarer, both because of Earth's example and because their lifespans may be short in astronomical terms. In a previous article ( I showed that if we translate this into distance, the probable distance of the closest technological civilization to us could be thousands of light years. Even if you find a closer culture, your opponent is probably right: due to the great distances even to the nearest stars, the only realistic form of communication would be the exchange of radio signals, perhaps in the form of pictures and charts.

  8. Omri,

    Glad you liked the mafia analogy, but thank you it's still frustrating to know that even though the chance of life in other places in the universe is probably quite high, the chance of us ever meeting them in our lifetime is probably zero.

    The only thing that might be possible if intelligent life exists on a relatively close planet is that they would send us pictures/videos of themselves, of their planet, of the cities they live in, that would be really amazing.

  9. Rival, I liked the example of the mafia. At the Emanuel headquarters, he wrote
    "He who thinks we are alone in the universe is like one who thinks he is alone on earth"
    My response to his words also fits your example:
    "A surprisingly accurate comparison: the number of planets similar to Earth in size and climate in our galaxy alone is about ten billion, similar to the number of humans on Earth. And in the universe visible to our eyes there are about a billion galaxies"
    In any case, it is not about the spread of life from one planet to another through bodies such as meteorites (a theory called transpermia, and refers to the spread of life within one solar system) but rather the spontaneous and independent appearance of life on planets with suitable conditions in different solar systems. If the Milky Way galaxy alone has tens of billions of such planets, as Kepler space telescope observations have convincingly demonstrated, it is easy to calculate the apparent distance to the nearest solar system where there are planets with conditions suitable for the development of life, about 10 light years.
    We still do not have the technological ability to determine whether life of any kind has really developed on all or some of these planets, but soon - a decade or less from now - it is very possible and such observations will be possible.

  10. Avi Cohen
    Living beings survived the Columbia accident and reached Earth. On the other hand, during a long stay in space there is a risk of exposure to radiation. And on the third hand - it could be that the radiation helps the formation of life.

    In any case - it is unlikely that life was created only with us.

  11. Avi Cohen,

    As I explained earlier to the miracles in the bakery example, I was not trying to demonstrate a situation of contagion from one loaf of bread to another, but rather a statistical principle according to which if a spot of mold has developed on one baker, then most likely there are other baked goods in this huge bakery on which mold has also developed *independently*.

    Overall, our universe is quite homogeneous in terms of the composition of the materials in it, and if life developed here, then it is very likely (statistically) that a similar thing happened in other solar systems and other galaxies independently, without connection to the Earth.

  12. miracles and a rival,
    I also support the hypothesis that life is common in the universe, and more than that, but the article talks about life in other solar systems. The example with the mold is true for transferring spores from one planet in the same system to another, but when we talk about other solar systems, we are talking about transferring to a loaf of bread in a bakery in a neighboring country.
    The question is, is it possible to assume that asteroids from KDWA were ejected from KDWA and reached our nearest neighbor, Alpha Centauri, and is it possible to survive the journey?
    It would be interesting to know what speed an asteroid ejected from the Earth and deflected out of the solar system reaches? Can we assume that they reach the speeds of the Voyager satellites? If so, they would have had enough time to reach our nearest stars.
    Is it possible that within large clumps of asteroids a life system with organisms will be preserved?

  13. Miracles,

    Interesting, I didn't know, how does this happen? I imagine you're not talking about the spaceships we sent there 🙂

    I like more the theory according to which maybe life started thanks to comets. We know they contain organic compounds and maybe even the first replicating molecule was formed on one of them. It is enough that a planet like Earth happened to pass within the long trail of a comet and already its atmosphere was sown with the seeds of life, or with organic compounds that are the basis of life.

    In any case, in the example I gave, I was actually trying to demonstrate something else, not "contagion" from one planet to its neighbors, but I was trying to show that statistically the chance that life only developed here and not anywhere else in the universe is pretty close to zero.

    Overall, looking at the universe, it is quite homogeneous in its composition, it doesn't really make sense that for 13.8 billion years only here was life able to develop (like a single tiny spot of mold in a huge bakery, and not a single spot of mold on any other bakery).

  14. rival
    Your example is better than you think 🙂 We know that hundreds of kilograms of material from Earth reaches Mars every year, and vice versa.
    So, it is unlikely that if there is mold on one loaf then the mold will spread to other loaves?

  15. Simple logic in my opinion, you walk into a huge bakery the size of a continent with tens of billions of shelves filled with loaves of bread, buns, challahs, baguettes... You happen to approach one of the shelves and among the different pastries you suddenly notice a small spot of mold on one of the pastries.

    What do you think the odds are that this is the only spot of mold in this entire huge bakery and that no other loaf of bread or bun has another spot of mold on it?

    (And I hope humanity will forgive me for the comparison)

  16. I am copying again a message I posted here not long ago:

    Simple logic in my opinion, you walk into a huge bakery the size of a continent with tens of billions of shelves filled with loaves of bread, buns, challahs, baguettes... You happen to approach one of the shelves and among the different pastries you suddenly notice a small spot of mold on one of the pastries.

    What do you think the odds are that this is the only spot of mold in this entire huge bakery and that no other loaf of bread or bun has another spot of mold on it? Zero chance if you ask me.

    (I hope humanity will forgive me for the comparison)

  17. A surprisingly accurate comparison: the number of planets similar to Earth in size and climate in our galaxy alone is about ten billion, similar to the number of humans on Earth. And in the universe visible to our eyes there are about a billion galaxies

  18. Who thinks we are alone in the universe is like one who thinks he is alone on earth
    In other words stupid

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