The weather forecast for most exoplanets is disappointing. The scorching sun, annual floods and deep snow significantly complicate the life of local residents.
Scientists are interested in the habitability of other planets for a number of reasons, political, financial, humanitarian and scientific. They want to understand how our own climate is changing.
How will we live in the climate of the future and what can we do to stem the rising tide of the greenhouse effect. After all, a little more and paradise until the Earth will be hopelessly lost.
It is unlikely that we will seriously concern ourselves with the search for clean energy sources or persuade politicians to deal with climate issues at the expense of financial gain. Much more interesting is the question: when will we see aliens?
The habitable zone, also known as the "Goldilocks zone," is the region around a star where the planet's average temperature allows the liquid water we're so used to to exist. We hunt for liquid water, not only for future use, but also to find a clue: maybe there could be other life somewhere.
Problems outside this zone are fairly obvious. If it gets too hot, the environment will become an unbearable steam bath, or it will begin to break down the water into oxygen and hydrogen.
Then oxygen will combine with carbon, forming carbon dioxide, and hydrogen will escape into space. This happens with Venus.
If the planet is too cold, the water will form solid pieces. There might be pockets of liquid water under the crust of ice, but overall it's not a very pleasant place to live.
We found this on Mars and the moons of Jupiter and Saturn. And if you can roughly define a potentially habitable zone, then this is the place where liquid water could exist.
Unfortunately, this equation does not only consist of the distance to the star and the amount of energy produced. The planet's atmosphere plays a major role.
You will be surprised, but Venus and Mars are in the potentially habitable zone of the solar system. Venus's atmosphere is so thick that it traps the Sun's energy and creates an inhospitable furnace that will melt any hint of life in less than two cups of tea for this gentleman. On Mars, the opposite is true.
The thin atmosphere cannot hold heat at all, so the planet is very cold. Improve the atmospheres of both planets - and get worlds that are quite capable of sheltering life.
Perhaps we could push them together and mix the atmospheres? Need to think. When we look at other worlds in the Milky Way and try to figure out if there is life there, it's not enough just to assess their location in the Goldilocks zone.
We need to know the shape of the atmosphere. Astronomers have found planets located in habitable zones around other stars, but these worlds don't appear to be particularly well located for life.
They revolve around red dwarf stars. In principle, living in reddish reflections is not so bad, but there is one problem.
Red dwarfs tend to behave very badly when they are young. They generate powerful flares and coronal mass ejections.
This clears the surface of any planet that gets too close. True, there is some hope.
After a few million years of high activity, these red dwarf stars settle down and begin to suck on their reserves of hydrogen, with a potential of trillions of years. If life can survive long enough in the early days of a star, a long, happy life can await. When you're thinking of a new home among the stars or trying to find new life in the universe, look for planets in the potentially habitable zone.
According to a Yale University (USA) researcher, in the search for habitable worlds, it is necessary to make room for the second “Goldilocks” condition.
For many decades, it was thought that a key factor in determining whether a planet could support life was its distance from its sun. In our solar system, for example, Venus is too close to the Sun, Mars is too far away, and Earth is just right. Scientists call this distance the “habitable zone” or “Goldilocks zone”.
It was also believed that the planets were able to independently regulate their internal temperature with the help of mantle convection and underground displacement of rocks caused by internal heating and cooling. The planet may initially be too cold or too hot, but will eventually come to the right temperature.
New study published in the journal Science Advances August 19, 2016, shows that just being in the habitable zone is not enough to sustain life. The planet must initially have the required internal temperature.
A new study has shown that for the origin and maintenance of life, the planet must have a certain temperature. Credit: Michael S. Helfenbein/Yale University
“If you collect all kinds of scientific data about how the Earth has evolved in the last few billion years and try to make sense of it, you eventually realize that convection in the mantle is pretty indifferent to internal temperature,” said Jun Korenaga, author of the study and professor of geology and geophysics at Yale University. Korenaga presented a general theoretical framework that explains the degree of self-regulation expected for convection in the mantle. The scientist suggested that self-regulation is hardly a characteristic of terrestrial planets.
“The absence of a self-regulating mechanism is of great importance for planetary habitability. Planet formation research suggests that terrestrial planets are formed by powerful impacts, and the outcome of this highly random process is known to be highly variable,” writes Korenaga.
A variety of sizes and internal temperatures would not hinder planetary evolution if the mantle self-regulated. What we take for granted on our planet, including oceans and continents, would not exist if the Earth's internal temperature was not in a certain range, which means that the beginning of Earth's history was not too hot or too cold.
NASA's Institute of Astrobiology supported the study. Korenaga is a co-researcher on NASA's Alternative Earths project team. The team is busy asking how the Earth maintains a permanent biosphere throughout most of its history, how the biosphere manifests itself in planetary-scale "biosignatures", and the search for life inside and outside the solar system.
We have discovered hundreds of exoplanets in the galaxy. But only a few of them have the right combination of factors to support life, like the Earth. The weather forecast for most exoplanets is disappointing. The scorching sun, annual floods and deep snow significantly complicate the life of the local inhabitants (if they exist, of course).
The bad news is that planet Earth is the only habitable place in the entire universe, as far as we know. As a species, we are interested in the habitability of other planets for a variety of reasons, political, financial, humanitarian, and scientific. We want to understand how our own climate is changing. How will we live in the climate of the future and what can we do to stem the rising tide of the greenhouse effect. After all, a little more and paradise until the Earth will be hopelessly lost.
It is unlikely that we will seriously concern ourselves with the search for clean energy sources or persuade politicians to deal with climate issues at the expense of financial gain. Much more interesting is the question: when will we see aliens?
The habitable zone, also known as the "Goldilocks zone," is the region around a star where the planet's average temperature allows the liquid water we're so used to to exist. We hunt for liquid water, not only for future use, but also to find a clue: maybe there could be other life somewhere. After all, is it logical?
Problems outside this zone are fairly obvious. If it gets too hot, the environment will become an unbearable steam bath, or it will begin to break down the water into oxygen and hydrogen. Then oxygen will combine with carbon, forming carbon dioxide, and hydrogen will escape into space.
This happens with Venus. If the planet is too cold, the water will form solid pieces. There might be pockets of liquid water under the crust of ice, but overall it's not a very pleasant place to live. We found this on Mars and the moons of Jupiter and Saturn. And if you can roughly define a potentially habitable zone, then this is the place where liquid water could exist.
Unfortunately, this equation does not only consist of the distance to the star and the amount of energy produced. The planet's atmosphere plays a major role. You will be surprised, but Venus and Mars are in the potentially habitable zone of the solar system.
The atmosphere of Venus is so thick that it traps the energy of the Sun and creates a furnace unfavorable for life that will melt any hint of life faster than you can say "two cups of tea for this gentleman."
On Mars, the opposite is true. The thin atmosphere cannot hold heat at all, so the planet is very cold. Improve the atmospheres of both planets - and get worlds that are quite able to shelter life. Perhaps we could push them together and mix the atmospheres? Need to think.
When we look at other worlds in the Milky Way and try to figure out if there is life there, it's not enough just to assess their location in the Goldilocks zone. We need to know the shape of the atmosphere.
Astronomers have found planets located in habitable zones around other stars, but these worlds don't appear to be particularly well located for life. They revolve around red dwarf stars. In principle, living in reddish reflections is not so bad, but there is one problem. Red dwarfs tend to behave very badly when they are young. They generate powerful flares and coronal mass ejections. This clears the surface of any planet that gets too close.
True, there is some hope. After a few million years of high activity, these red dwarf stars settle down and begin to suck on their reserves of hydrogen, with a potential of trillions of years. If life can survive long enough in the early days of a star, a long, happy life can await.
When you're thinking of a new home among the stars or trying to find new life in the universe, look for planets in the potentially habitable zone. But do not forget that this is a very conditional guideline.
© Vladimir Polozhentsev, 2016
Created with the intelligent publishing system Ridero
Belt of Goldilocks
The meeting of the astronomy club "Yellow Dwarf" was held in the assembly hall of the former weaving factory. The monthly event was in full swing. They expected the arrival of a representative of Roskosmos, which gave the meeting a special significance. The famous ufologist Daniil Panteleymonovich Zakamsky finished a report on the influence of UFOs on earthly civilization. He is a retired ensign of the Air Defense Forces.
“Therefore,” he poked with a ballpoint pen into small but extensive diagrams on a paper attached to the podium, “it can be said with certainty that a meteoroid in the vicinity of Chelyabinsk was shot down by an alien ship from the constellation Tau Ceti.
The lovers buzzed, began to talk violently. Golden-haired and rather attractive, despite her age, the chairman of the club, Vera Ignatievna Krupitsina, who was once the party organizer of this carpet weaving enterprise, hit the decanter with a pencil:
If anyone has questions, please express your thoughts in a constructive way.
- What did they shoot down? - Slava Janson, an elderly student of the Institute of Food Industry, raised his hand in disbelief. “Nuclear missile, laser beam, or anti-gravity gun?”
“You are being ironic in vain, young man,” the speaker was offended. - With a weight of a superbolide of approximately 80 thousand tons and a speed of 30 kilometers per second, the explosion power in the atmosphere was 1.2 megatons of TNT. Using the empirical formula, - Zakamsky nervously tapped with ink knuckles according to the scheme, - where t is the period of the signal with the maximum amplitude, we come to the conclusion that the explosion should have been at least one and a half times weaker. Where did the extra energy come from? Only from extraneous influence on the object. That is why on that day, February 15, eyewitnesses observed several unidentified flying objects near Chebarkul, as well as over the territory of Kazakhstan.
“Suppose,” Janson did not back down. “But what makes you think that the ship came from Tau Ceti?”
“From the fact that the satellites of Jupiter and Saturn rotate synchronously,” someone in the gallery quipped.
“You are being ironic in vain,” repeated the speaker, apparently a frequently used phrase. – Where else? Alpha Centauri B is, of course, closer to us, only four and a half light years away. The binary star has terrestrial planets, but they are in hellish conditions. The five satellites of Tau Ceti feel great in the Goldilocks belt. That is, in the so-called living, life-friendly zone.
“Well, this is not yet proof,” the student waved his hand in disappointment.
“And the weapon,” Zakamsky said in earnest, “could also be anti-gravity. Yes. Based on dark energy.
No one was making any noise in the hall, but the chairman, just in case, rang the decanter again, casting a stern glance over the motley audience:
Who else wants? There are no applicants. Thank you, sir, Zakamsky. I think science will figure out who blew up the Chebarkul meteorite. Now let's move on to the topic of asteroid and comet threats from the Oort cloud.
“Wait,” a tall young man rose from the second row at the end. – I would like to clarify something. Why do aliens need to fly to us on mechanical, I wanted to say, material vehicles?
Accepting another challenge with pleasure, Zakamsky held a pointer to his stomach, like a Norman pike. He glanced at the blond with unruly hair, a hard chin and ironic eyes. This one just won't come off.
Daniil Panteleimonovich depicted a sarcastic smile on his sharp-angled face, the color of the Martian desert, twisted his head like a bird, flashed glasses powerful as telescopes:
- I do not understand the question.
- You all understand, - a man got out into the aisle between the rows. He patted his bouncy hair with his hand, but it immediately returned to its original shape.
“It’s customary for us to introduce ourselves,” Krupitsina raised her eyebrows menacingly and blew her nose desperately. She had a cold and dreamed of woolen socks and a glass of hot milk with honey.
- Alexander Greenwich, doctor. Urologist.
Laughter erupted in the hall. "Wrong address?"
For those who didn't hear. To overcome interstellar space, civilization must be at a very high level of development.
“Undoubtedly,” the speaker nodded, tensely expecting a trick.
- Let's say that the inhabitants of one of the planets of Tau Ceti managed to create near-light or even superluminal technologies for starships. But if so, their civilization has long lived in the virtual world. Even for us, to find out what is happening, for example, in Australia, it is not necessary to fly there. That's what the Internet is for.
- You want to say…
- Exactly. If they had a desire to help us, they would have done it at a distance. They don't need to travel through space on titanium tin cans with anti-gravity or some other engines. We just wouldn't see them. They have been viobry for a long time.
– Virtual images. That is, all talk about UFOs is just nonsense. Accordingly, your report is complete nonsense.
- Excuse me, - Zakamsky soared, - but thousands, tens of thousands of eyewitnesses have seen and continue to observe unidentified flying objects everywhere. You can't argue against this fact!
- Ionospheric phenomena, - the young man did not tear his blue eyes away from the ufologist. - Two options. Either civilizations in our galaxy began to develop at the same time and, like us, they still do not have the opportunity to move from star to star, or they have gone so far in their development that, I repeat, they live in a virtual world.
- You said about Australia, - the ufologist took the pointer like a saber, - but nothing can be changed on this continent via the Internet. At least try to stop the rain.
- Not yet. When special repeaters with power plants appear over the continents, everything will be real. Including knocking down meteorites. Although it is foolishness to destroy them in the atmosphere. Asteroids and comets must be eliminated on the distant approaches to the planet. You know it very well. It is possible that once the aliens were with us and made the Moon a repeater. But it is not a fact that it was they who shot down the heavenly wanderer near Chelyabinsk. The meteoroid exploded under the influence of the atmosphere.
- In your opinion, it turns out that the entire intelligent universe is a virtual world? Lives in a computer space? What about people then? For what? Zakamsky pursed his capricious lips.
– Life originates in the material environment, on the planets. It develops, and then civilization joins the general virtual world. Or the galaxy or the whole universe, I don't know. People have already touched the virtual. In a thousand years, a maximum of one and a half years, contact will be established with us, and we will finally plunge into it.
– And impersonal, aspiring to nothing, immoral pixel creatures live in this virtual of yours?! shouted Zakamsky as if at a wedding. The Internet is absolutely immoral!
- From what? Morality can and should be observed everywhere. Whoever strives for this is moral. I think highly spirituality is the first law of space. The virtual world of the universe is a single bank of the divine, if we use our terminology, mind, but the personality is not blurred there, it exists.
- I repeat the question, why are we on Earth?
For a moment there was an electric silence in the hall. Even the chairwoman no longer tapped the decanter. She shrugged. In the eyes of the former party organizer, the bright fire of Tau Ceti burned.
Finally the man spoke:
- Every person is a god. Limited action, of course. We can control our own destiny, and if we wish and persevere, we can influence the fate of the entire planet. This is already a lot. No god is omnipotent, since space is limitless. There is always someone above someone. The immutable law of nature, acting everywhere. Man exists in order to sooner or later become a stronger god. Virtual. Rather, part of a single all-encompassing mind.
If an unusual incident happened to you, you saw a strange creature or an incomprehensible phenomenon, you had an unusual dream, you saw a UFO in the sky or became a victim of alien abduction, you can send us your story and it will be published on our website ===> .
Take a look at the scattering of stars in the black night sky - they all contain amazing worlds like our solar system. According to the most conservative estimates, the Milky Way galaxy contains more than a hundred billion planets, some of which may be similar to the Earth.
New information about "alien" planets - exoplanets- opened the Kepler space telescope, exploring the constellations in anticipation of the moment when a distant planet will be in front of its luminary.
The orbital observatory was launched in May 2009 specifically to search for exoplanets, but failed four years later. After many attempts to return the telescope to work, NASA was forced to decommission the observatory from its "space fleet" in August 2013. Nevertheless, over the years of observations, Kepler has received so much unique data that it will take several more years to study them. NASA is already gearing up to launch Kepler's successor, the TESS telescope, in 2017.
Super-Earths in the Goldilocks Belt
Today, astronomers have identified almost 600 new worlds out of 3,500 candidates for the title of "exoplanet". It is believed that among these celestial bodies, at least 90% may turn out to be "true planets", and the rest - double stars, "brown dwarfs" that have not grown to stellar sizes and clusters of large asteroids.
Most of the new planet candidates are gas giants like Jupiter or Saturn, as well as super-Earths - rocky planets several times larger than ours.
Naturally, far from all planets fall into the field of view of Kepler and other telescopes. Their number is estimated at only 1-10%.
To definitely identify an exoplanet, it must be repeatedly fixed on the disk of its star. It is clear that most often it is located close to its sun, because then its year will last only a few Earth days or weeks, so astronomers will be able to repeat observations many times.
Such planets in the form of hot balls of gas often turn out to be "hot Jupiters", and one in six is like a flaming super-Earth covered with seas of lava.
Of course, in such conditions, the protein life of our type cannot exist, but among hundreds of inhospitable bodies there are pleasant exceptions. So far, more than a hundred terrestrial planets have been identified, located in the so-called habitable zone, or goldilocks belt.
This fairy-tale character was guided by the principle "no more, no less." Similarly, the rare planets included in the "zone of life", the temperature should be within the limits of the existence of liquid water. Moreover, 24 planets out of this number have a radius less than two radii of the Earth.
However, so far only one of these planets has the main features of the Earth's twin: it is located in the Goldilocks zone, is close to Earth's size and is part of a yellow dwarf system similar to the Sun.
In the world of red dwarfs
However, astrobiologists, persistently looking for extraterrestrial life, do not lose heart. Most of the stars in our galaxy are small cool and dim red dwarfs. According to modern data, red dwarfs, being about half the size and colder than the Sun, make up at least three-quarters of the "stellar population" of the Milky Way.
Around these "solar cousins" miniature systems the size of the orbit of Mercury revolve, and they also have their own Goldilocks belts.
Astrophysicists at the University of California at Berkeley even compiled a special TERRA computer program, with the help of which a dozen terrestrial twins were identified. All of them are close to their life zones near small red luminaries. All this greatly increases the chances of the presence of extraterrestrial centers of life in our galaxy.
Red dwarfs, in the vicinity of which Earth-like planets have been found, were previously thought to be very quiet stars, and flares accompanied by plasma ejections rarely occur on their surfaces.
As it turned out, in fact, such luminaries are even more active than the Sun.
Powerful cataclysms constantly occur on their surface, generating hurricane gusts of "stellar wind" that can overcome even the powerful magnetic shield of the Earth.
However, for proximity to their star, many twins of the Earth can pay a very high price. Fluxes of radiation from frequent flashes on the surface of red dwarfs can literally “lick off” part of the atmosphere of planets, making these worlds uninhabitable. At the same time, the danger of coronal ejections is enhanced by the fact that a weakened atmosphere will poorly protect the surface from charged particles of hard ultraviolet and x-rays of the “stellar wind”.
In addition, there is a danger that the magnetospheres of potentially habitable planets will be suppressed by the strongest magnetic field of red dwarfs.
Broken Magnetic Shield
Astronomers have long suspected that many red dwarfs have a powerful magnetic field that can easily break through the magnetic shield surrounding potentially habitable planets. To prove this, a virtual world was built in which our planet rotates around a similar star in a very close orbit in the "life zone".
It turned out that very often the magnetic field of a dwarf not only strongly deforms the Earth's magnetosphere, but even drives it under the surface of the planet. In such a scenario, in just a few million years, we would have no air or water left, and the entire surface would be scorched by cosmic radiation.
Two interesting conclusions follow from this. The search for life in red dwarf systems may turn out to be completely hopeless, and this is another explanation for the "great silence of the cosmos."
However, perhaps we cannot detect extraterrestrial intelligence in any way because our planet was born too early ...
Who can live on distant exoplanets? Maybe such creatures?
The sad fate of the firstborn
Analyzing data obtained with the help of the Kepler and Hubble telescopes, astronomers found that the process of star formation in the Milky Way has slowed down significantly. This is due to the growing shortage of building materials in the form of dust and gas clouds.
Nevertheless, there is still a lot of material left in our galaxy for the birth of stars and planetary systems. Moreover, in a few billion years, our stellar island will collide with the giant galaxy of the Andromeda Nebula, which will cause a colossal burst of star formation.
Against this background of future galactic evolution, the sensational news was recently heard that four billion years ago, at the time of the formation of the solar system, only a tenth of the potentially habitable planets existed.
Considering that it took several hundred million years for the birth of the simplest microorganisms on our planet, and several billion years more developed forms of life were formed, it is highly likely that intelligent aliens will appear only after the extinction of the Sun.
Perhaps here lies the solution to the intriguing Fermi paradox, which was once formulated by an outstanding physicist: and where are these aliens? Or does it make sense to look for answers on our planet?
Extremophiles on Earth and in space
The more we become convinced of the uniqueness of our place in the Universe, the more often the question arises: can life exist and develop in worlds completely different from ours?
The answer to this question is given by the existence on our planet of amazing organisms - extremophiles. They got their name for their ability to survive in extreme temperatures, poisonous environments and even airless space. Marine biologists have found similar creatures in underground geysers - "sea smokers".
There they thrive under colossal pressure in the absence of oxygen at the very edge of hot volcanic vents. Their "colleagues" are found in salty mountain lakes, hot deserts and subglacial reservoirs of Antarctica. There are even "tardigrade" microorganisms that endure the vacuum of space. It turns out that even in the radiation environment near red dwarfs, some "extreme microbes" can arise.
Acid lake located in Yellowstone. Red plaque - acidophilus bacteria
Tardigrades can exist in the vacuum of space
Academic evolutionary biology believes that life on Earth originated from chemical reactions in a "warm shallow pool" penetrated by ultraviolet and ozone streams from raging "lightning storms." On the other hand, astrobiologists know that the chemical building blocks of life are found on other worlds as well. For example, they were noticed in gas and dust nebulae and satellite systems of our gas giants. This, of course, is far from a “full life”, but the first step towards it.
The “standard” theory of the origin of life on Earth has recently received a strong blow from…. geologists. It turns out that the first organisms are much older than previously thought, and formed in a completely unfavorable environment of a methane atmosphere and boiling magma pouring out of thousands of volcanoes.
This makes many biologists think about the old hypothesis of panspermia. According to it, the first microorganisms originated somewhere else, say, on Mars, and came to Earth in the core of meteorites. Perhaps the ancient bacteria had to travel a longer distance in cometary nuclei from other star systems.
But if this is so, then the paths of "cosmic evolution" can lead us to "brothers in origin" who drew the "seeds of life" from the same source as we...
