In a groundbreaking first, British researchers have identified 50 new planets using artificial intelligence.

A research team led by David Armstrong at the University of Warwick in the United Kingdom&nbsp;created a&nbsp;machine learning&nbsp;algorithm and trained it using data on confirmed planets and false-positives from&nbsp;NASA's retired Kepler mission.&nbsp;

The scientists&nbsp;then used the algorithm on a dataset of still unconfirmed planetary candidates from Kepler, resulting in fifty new confirmed planets and the first to be validated by machine learning.

Also read:&nbsp;<a href="https://www.wionews.com/science/growing-dent-on-earths-magnetic-field-can-damage-satellites-and-navigation-321602" hreflang="en">Growing dent on Earth’s magnetic field can damage satellites and navigation</a>

Their results were reported in a new study published in the Monthly Notices of the Royal Astronomical Society, where they also perform the first large scale comparison of such planet validation techniques.

Previous machine learning techniques have ranked candidates, but never determined the probability that a candidate was a true planet by themselves, a required step for planet validation.

Also read:&nbsp;<a href="https://www.wionews.com/science/car-sized-asteroid-becomes-closest-ever-seen-passing-earth-nasa-321591" hreflang="en">Car-sized asteroid becomes closest ever seen passing Earth: NASA</a>

These 50 exoplanets,&nbsp;range from worlds as large as Neptune to smaller than the Earth, with orbits as long as 200 days to as little as a single day. By confirming that these fifty planets are real, astronomers can now prioritise these for further observations with dedicated telescopes.

"The algorithm we have developed lets us take fifty candidates across the threshold for planet validation, upgrading them to real planets. We hope to apply this technique to large samples of candidates from current and future missions like TESS and PLATO,"&nbsp;Armstrong said.

"In terms of planet validation, no-one has used a machine learning technique before. Machine learning has been used for ranking planetary candidates but never in a probabilistic framework, which is what you need to truly validate a planet. Rather than saying which candidates are more likely to be planets, we can now say what the precise statistical likelihood is. Where there is less than a 1 per cent&nbsp;chance of a candidate being a false positive, it is considered a validated planet," added Armstrong.

"Probabilistic approaches to statistical machine learning are especially suited for an exciting problem like this in astrophysics that requires incorporation of prior knowledge,&nbsp;from experts like Dr Armstrong&nbsp;and quantification of uncertainty in predictions. A prime example when the additional computational complexity of probabilistic methods pays off significantly," Dr Theo Damoulas from the University of Warwick Department of Computer Science, and Deputy Director, Data Centric Engineering and Turing Fellow at The Alan Turing Institute, said.

Once built and trained the algorithm is faster than existing techniques and can be completely automated, making it ideal for analysing the potentially thousands of planetary candidates observed in current surveys like TESS.

The researchers argue that it should be one of the tools to be collectively used to validate planets in future.

"Almost 30 per cent of the known planets to date have been validated using just one method, and that`s not ideal. Developing new methods for validation is desirable for that reason alone. But machine learning also lets us do it very quickly and prioritise candidates much faster. We still have to spend time training the algorithm, but once that is done it becomes much easier to apply it to future candidates," Dr Armstrong said.

"You can also incorporate new discoveries to progressively improve it. A survey like TESS is predicted to have tens of thousands of planetary candidates and it is ideal to be able to analyse them all consistently. Fast, automated systems like this that can take us all the way to validated planets in fewer steps let us do that efficiently," added Dr Armstrong.

In a groundbreaking first, British researchers have identified 50 new planets using artificial intelligence. A research team led by David Armstrong at the University of Warwick in the United Kingdom created a machine learning algorithm and trained it using data on confirmed planets and false-positives from NASA's retired Kepler mission.

In a groundbreaking first, British researchers have identified 50 new planets using artificial intelligence. A research team led by David Armstrong at the University of Warwick in the United Kingdom created a machine learning algorithm and trained it using data on confirmed planets and false-positives from NASA's retired Kepler mission. The scientists then used the algorithm on a dataset of still unconfirmed planetary candidates from Kepler, resulting in fifty new confirmed planets and the first to be validated by machine learning. Also read: Growing dent on Earth’s magnetic field can damage satellites and navigation Their results were reported in a new study published in the Monthly Notices of the Royal Astronomical Society, where they also perform the first large scale comparison of such planet validation techniques. Previous machine learning techniques have ranked candidates, but never determined the probability that a candidate was a true planet by themselves, a required step for planet validation. Also read: Car-sized asteroid becomes closest ever seen passing Earth: NASA These 50 exoplanets, range from worlds as large as Neptune to smaller than the Earth, with orbits as long as 200 days to as little as a single day. By confirming that these fifty planets are real, astronomers can now prioritise these for further observations with dedicated telescopes. "The algorithm we have developed lets us take fifty candidates across the threshold for planet validation, upgrading them to real planets. We hope to apply this technique to large samples of candidates from current and future missions like TESS and PLATO," Armstrong said. "In terms of planet validation, no-one has used a machine learning technique before. Machine learning has been used for ranking planetary candidates but never in a probabilistic framework, which is what you need to truly validate a planet. Rather than saying which candidates are more likely to be planets, we can now say what the precise statistical likelihood is. Where there is less than a 1 per cent chance of a candidate being a false positive, it is considered a validated planet," added Armstrong. "Probabilistic approaches to statistical machine learning are especially suited for an exciting problem like this in astrophysics that requires incorporation of prior knowledge, from experts like Dr Armstrong and quantification of uncertainty in predictions. A prime example when the additional computational complexity of probabilistic methods pays off significantly," Dr Theo Damoulas from the University of Warwick Department of Computer Science, and Deputy Director, Data Centric Engineering and Turing Fellow at The Alan Turing Institute, said. Once built and trained the algorithm is faster than existing techniques and can be completely automated, making it ideal for analysing the potentially thousands of planetary candidates observed in current surveys like TESS. The researchers argue that it should be one of the tools to be collectively used to validate planets in future. "Almost 30 per cent of the known planets to date have been validated using just one method, and that`s not ideal. Developing new methods for validation is desirable for that reason alone. But machine learning also lets us do it very quickly and prioritise candidates much faster. We still have to spend time training the algorithm, but once that is done it becomes much easier to apply it to future candidates," Dr Armstrong said. "You can also incorporate new discoveries to progressively improve it. A survey like TESS is predicted to have tens of thousands of planetary candidates and it is ideal to be able to analyse them all consistently. Fast, automated systems like this that can take us all the way to validated planets in fewer steps let us do that efficiently," added Dr Armstrong.

Artificial Intelligence identifies 50 new planets from NASA data

Astronomers have discovered two super-Earth exoplanets orbiting a star 11 light-years away from Earth, according to a new study published in the journal Science.

The planets can&nbsp;be among the best opportunities for finding life outside of our&nbsp;solar system and shed light on the&nbsp;potential of a third planet orbiting a bit further away from the star.

A team of astronomers working on the&nbsp;Red Dots project, which is attempting to find terrestrial exoplanets closest to our sun, observed the star using the European Southern Observatory in Chile.

Also see:&nbsp;<a href="https://www.wionews.com/photos/in-a-first-water-found-on-earth-like-planet-beyond-our-solar-system-249176">In a first, water found on earth-like planet beyond our solar system</a>

The researchers believe the proximity of this planetary system just 11 light-years away will enable it to be studied more in the future.

The system orbits around the star&nbsp;Gliese 887, which&nbsp;is a small, dim red dwarf star about half the mass of our sun. and the brightest red dwarf in the sky.

Also read:&nbsp;<a href="https://www.wionews.com/world/opinion-what-are-nasas-exo-planets-26807">What are NASA's exo-planets</a>

Super-Earths like the newly found planets have a higher mass than the Earth but are much smaller than the ice giants of our solar system, Uranus and Neptune.&nbsp;And both of them are close to the habitable zone of the star, a place where terrestrial planets can support liquid water on their surfaces.

RedDots astronomers who are looking for planets around red dwarfs,&nbsp;were able to infer the planets around the star by using a technique called "Doppler wobble", which lets them watch for the tiny movements of the star that are caused by the gravitational pull of the planets around them.

They found that the star appeared to be orbited by planets that have orbits that would give them years of just 9.3 and 21.8 days on Earth. That suggests the planets are moving very quickly around their star, faster even than Mercury.

Astronomers have discovered two super-Earth exoplanets orbiting a star 11 light-years away from Earth, according to a new study published in the journal Science.

Astronomers have discovered two super-Earth exoplanets orbiting a star 11 light-years away from Earth, according to a new study published in the journal Science. The planets can be among the best opportunities for finding life outside of our solar system and shed light on the potential of a third planet orbiting a bit further away from the star. A team of astronomers working on the Red Dots project, which is attempting to find terrestrial exoplanets closest to our sun, observed the star using the European Southern Observatory in Chile. Also see: In a first, water found on earth-like planet beyond our solar system The researchers believe the proximity of this planetary system just 11 light-years away will enable it to be studied more in the future. The system orbits around the star Gliese 887, which is a small, dim red dwarf star about half the mass of our sun. and the brightest red dwarf in the sky. Also read: What are NASA's exo-planets Super-Earths like the newly found planets have a higher mass than the Earth but are much smaller than the ice giants of our solar system, Uranus and Neptune. And both of them are close to the habitable zone of the star, a place where terrestrial planets can support liquid water on their surfaces. RedDots astronomers who are looking for planets around red dwarfs, were able to infer the planets around the star by using a technique called "Doppler wobble", which lets them watch for the tiny movements of the star that are caused by the gravitational pull of the planets around them. They found that the star appeared to be orbited by planets that have orbits that would give them years of just 9.3 and 21.8 days on Earth. That suggests the planets are moving very quickly around their star, faster even than Mercury.

Astronomers discover two super-Earths orbitting a star 11 light-years away

Astronomers have confirmed the existence of Proxima b, an Earth-size exoplanet orbiting the closest star to the&nbsp;sun.

The researchers determined that Proxima b is 1.17 times the mass of Earth and completes an orbit around its star, Proxima Centauri, every 11.2 Earth days.

The star, Proxima Centauri, is 4.2 light-years from the&nbsp;sun. Previously, scientists using the HARPS measurements said it was 1.3 Earth masses.

Also read:&nbsp;<a href="https://www.wionews.com/world/scientists-capture-stunning-image-revealing-birth-of-a-new-planet-300355">Scientists capture stunning image revealing birth of a new planet</a>

"Proxima b is a very special guy among all the known exoplanets: the closest exoplanet there will ever be to us, terrestrial in size, and within the habitable zone," said Christophe Lovis, study coauthor and researcher in the University of Geneva's astronomy department.

"In spite of the clear detection achieved by HARPS in 2016, it was necessary to have an independent confirmation from the new and much more powerful ESPRESSO, to lift any remaining doubts there could have been.

The study results were published last week in the journal Astronomy and&nbsp;Astrophysics.

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Proxima b is 20 times closer to its star than Earth is to the sun. Proxima Centauri is a low-mass red dwarf star, which means that even though the planet is close to the star, it receives similar energy that Earth does from the sun.

Proxima b is located within the habitable zone of its star, meaning that liquid water, and the suggestion of life, may be possible on the planet's surface.

However, Proxima Centauri is an active star that lashes the planet with X-rays, 400 times more than Earth receives from the sun. This could impact the chances for water and life on the planet.

The data from ESPRESSO also revealed a second signal hinting at the existence of more planets in our solar system, although the researchers weren't able to definitively detect what caused it.

The signal "may be caused by a planet just 30 per cent&nbsp;the mass of the Earth, which was completely undetectable before," Lovis said. This would make it the smallest planet ever measured using the radial velocity method.

Astronomers have confirmed the existence of Proxima b, an Earth-size exoplanet orbiting the closest star to the sun. The researchers determined that Proxima b is 1.

Astronomers have confirmed the existence of Proxima b, an Earth-size exoplanet orbiting the closest star to the sun. The researchers determined that Proxima b is 1.17 times the mass of Earth and completes an orbit around its star, Proxima Centauri, every 11.2 Earth days. The star, Proxima Centauri, is 4.2 light-years from the sun. Previously, scientists using the HARPS measurements said it was 1.3 Earth masses. Also read: Scientists capture stunning image revealing birth of a new planet "Proxima b is a very special guy among all the known exoplanets: the closest exoplanet there will ever be to us, terrestrial in size, and within the habitable zone," said Christophe Lovis, study coauthor and researcher in the University of Geneva's astronomy department. "In spite of the clear detection achieved by HARPS in 2016, it was necessary to have an independent confirmation from the new and much more powerful ESPRESSO, to lift any remaining doubts there could have been. The study results were published last week in the journal Astronomy and Astrophysics. Proxima b is 20 times closer to its star than Earth is to the sun. Proxima Centauri is a low-mass red dwarf star, which means that even though the planet is close to the star, it receives similar energy that Earth does from the sun. Proxima b is located within the habitable zone of its star, meaning that liquid water, and the suggestion of life, may be possible on the planet's surface. However, Proxima Centauri is an active star that lashes the planet with X-rays, 400 times more than Earth receives from the sun. This could impact the chances for water and life on the planet. The data from ESPRESSO also revealed a second signal hinting at the existence of more planets in our solar system, although the researchers weren't able to definitively detect what caused it. The signal "may be caused by a planet just 30 per cent the mass of the Earth, which was completely undetectable before," Lovis said. This would make it the smallest planet ever measured using the radial velocity method.

Astronomers confirm existence of an Earth-size exoplanet

On Monday, June 19, NASA held a media briefing to announce the completed catalogue of exoplanets from the Kepler Mission.

The catalogue lists 4,034 exoplanet discoveries, including 219 new finds. Ten of these new worlds are close in size to the Earth and reside within their star&rsquo;s habitable zone, a location that would permit liquid water on the surface of an Earth-like world.

These ten join roughly 40 other worlds found by Kepler as possible candidates for Earth&rsquo;s twin. But is the prospect of another Earth really the Kepler legacy?

Teeming with planets

While planets had been discovered around other stars since the early 1990s, the launch of the Kepler Space Telescope in 2009 resulted in them being found in droves. As the numbers increased from tens to thousands of exoplanets, astronomers were able to identify types of planets and speculate on their frequency through our Galaxy; Kepler had given us the ability to do statistics.

Our Solar System suggests there are just two flavours of the planet: Terrestrial worlds like the Earth with rocky surfaces and thin atmospheres, and gas giants like Jupiter, whose solid cores are buried beneath thousands of kilometres of enveloping gases.

This neat, bimodal picture is taken to pieces in the Kepler Mission catalogue.

The catalogue contents reveal gas giants that orbit their star closer than Mercury, other worlds so hot their surface must be molten magma and planets around binary stars like Luke Skywalker&rsquo;s fictional home world of Tatooine in the film franchise Star Wars.

But perhaps the most mysterious entries are the so-called super-Earths.

How super, really?

Over two-thirds of the planets in the Kepler Mission Catalogue have radii of between 1.1 and four Earths, placing them between Earth and Neptune in size. These super-Earths are the most common planet discovered, yet our own Solar System has no analogue to tell us what such worlds might be like.

Are they terrestrial planets with rocky surfaces or mini gas giants with crushing atmospheric pressures? As interest has mounted in the prospect of finding a habitable planet, a key question is whether any of these worlds have a solid surface.

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Our Solar System has only cold gas and ice giants and rocky terrestrial planets, but the Kepler Mission revealed many other planet types. (Others)
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At the media briefing, NASA revealed that the Kepler Mission catalogue had produced a clue. A recent journal paper had spotted a split in the distribution of super-Earth planet sizes.

While planets with radii of around 1.3 Earths and 2.4 Earths are equally common, planets with sizes between 1.5 and two Earth radii are much harder to find. The astronomers speculate that this is the division between giant rocky planets and gaseous mini-Neptunes.

Although this strong divide in the super-Earth population has not previously been observed, its location agrees with the small number of planets we have bulk density measurements for. These density values suggest that planets larger than about 1.6 Earth radii have thick, Neptune-like atmospheres.

But while the Kepler Space Telescope can give us both sizes and locations for exoplanets, it cannot tell us anything about their past or the present surface environment. We need theories to explain the different planet types identified within the catalogue.

Explaining super-Earths

One possibility for the split in the super-Earth population is that the rocky planets have had their atmospheres stripped by radiation pouring from a star. Alternatively, the rocky worlds may have formed later from the gas-rich planet-forming disc that dispersed before the planets could accrue a thick atmosphere.

We meet a similar problem for the 50 planets found within the habitable zone. Knowing only their size and location is not enough to determine if their surfaces are similar to the Earth.

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The Kepler Mission data helped reveal a split in the super-Earth planet population, separating large rocky planets from small gas giants (B. J. Fulton). (Others)
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A difference in geology could create a very different atmosphere to our own, or the inability to create protective magnetic fields to shield the planet from sterilising stellar flares. The temperature may even be perfect for liquid water, but the planet entirely dry.

Without being able to probe surfaces, the Kepler telescope was never designed to find a true Earth twin. Rather, the mission catalogue tells us that planets can form around nearly every star and exist in a huge variety of conditions.

The Kepler Mission spanned four years (2009 to 2013), exploring a patch of sky in the Cygnus constellation. In May 2013, the second of the telescope&rsquo;s four gyroscope-like reaction wheels failed and it was unable to keep a stable position.

But the telescope continues to search the sky near the ecliptic plane (where the zodiac constellations lie), using radiation pressure from the Sun for positioning. This has become the K2 mission and has already found over 500 planets.

Future missions such as TESS and JWST (planned launch in 2018) and Ariel (planned launch in 2026) will add to this number, and begin to probe the environment of these worlds.

The Kepler Mission catalogue told us where to look, now we can begin to uncover what alien worlds are truly like.

This article was originally published on <a href="http://theconversation.com" rel="nofollow">The Conversation</a>. Read the <a href="https://theconversation.com/kepler-mission-has-released-its-catalogue-of-exoplanets-but-what-have-we-learnt-about-these-worlds-79817" rel="nofollow">original article</a>.

(Disclaimer: The opinions expressed above are the personal views of the author and do not reflect the views of ZMCL)

NASA's Kepler Mission has identified thousands of exoplanets but leaves a lot of questions about alien worlds.

On Monday, June 19, NASA held a media briefing to announce the completed catalogue of exoplanets from the Kepler Mission. The catalogue lists 4,034 exoplanet discoveries, including 219 new finds. Ten of these new worlds are close in size to the Earth and reside within their star’s habitable zone, a location that would permit liquid water on the surface of an Earth-like world. These ten join roughly 40 other worlds found by Kepler as possible candidates for Earth’s twin. But is the prospect of another Earth really the Kepler legacy? Teeming with planets While planets had been discovered around other stars since the early 1990s, the launch of the Kepler Space Telescope in 2009 resulted in them being found in droves. As the numbers increased from tens to thousands of exoplanets, astronomers were able to identify types of planets and speculate on their frequency through our Galaxy; Kepler had given us the ability to do statistics. Our Solar System suggests there are just two flavours of the planet: Terrestrial worlds like the Earth with rocky surfaces and thin atmospheres, and gas giants like Jupiter, whose solid cores are buried beneath thousands of kilometres of enveloping gases. This neat, bimodal picture is taken to pieces in the Kepler Mission catalogue. The catalogue contents reveal gas giants that orbit their star closer than Mercury, other worlds so hot their surface must be molten magma and planets around binary stars like Luke Skywalker’s fictional home world of Tatooine in the film franchise Star Wars. But perhaps the most mysterious entries are the so-called super-Earths. How super, really? Over two-thirds of the planets in the Kepler Mission Catalogue have radii of between 1.1 and four Earths, placing them between Earth and Neptune in size. These super-Earths are the most common planet discovered, yet our own Solar System has no analogue to tell us what such worlds might be like. Are they terrestrial planets with rocky surfaces or mini gas giants with crushing atmospheric pressures? As interest has mounted in the prospect of finding a habitable planet, a key question is whether any of these worlds have a solid surface. Our Solar System has only cold gas and ice giants and rocky terrestrial planets, but the Kepler Mission revealed many other planet types. (Others) × At the media briefing, NASA revealed that the Kepler Mission catalogue had produced a clue. A recent journal paper had spotted a split in the distribution of super-Earth planet sizes. While planets with radii of around 1.3 Earths and 2.4 Earths are equally common, planets with sizes between 1.5 and two Earth radii are much harder to find. The astronomers speculate that this is the division between giant rocky planets and gaseous mini-Neptunes. Although this strong divide in the super-Earth population has not previously been observed, its location agrees with the small number of planets we have bulk density measurements for. These density values suggest that planets larger than about 1.6 Earth radii have thick, Neptune-like atmospheres. But while the Kepler Space Telescope can give us both sizes and locations for exoplanets, it cannot tell us anything about their past or the present surface environment. We need theories to explain the different planet types identified within the catalogue. Explaining super-Earths One possibility for the split in the super-Earth population is that the rocky planets have had their atmospheres stripped by radiation pouring from a star. Alternatively, the rocky worlds may have formed later from the gas-rich planet-forming disc that dispersed before the planets could accrue a thick atmosphere. We meet a similar problem for the 50 planets found within the habitable zone. Knowing only their size and location is not enough to determine if their surfaces are similar to the Earth. The Kepler Mission data helped reveal a split in the super-Earth planet population, separating large rocky planets from small gas giants (B. J. Fulton). (Others) × A difference in geology could create a very different atmosphere to our own, or the inability to create protective magnetic fields to shield the planet from sterilising stellar flares. The temperature may even be perfect for liquid water, but the planet entirely dry. Without being able to probe surfaces, the Kepler telescope was never designed to find a true Earth twin. Rather, the mission catalogue tells us that planets can form around nearly every star and exist in a huge variety of conditions. The Kepler Mission spanned four years (2009 to 2013), exploring a patch of sky in the Cygnus constellation. In May 2013, the second of the telescope’s four gyroscope-like reaction wheels failed and it was unable to keep a stable position. But the telescope continues to search the sky near the ecliptic plane (where the zodiac constellations lie), using radiation pressure from the Sun for positioning. This has become the K2 mission and has already found over 500 planets. Future missions such as TESS and JWST (planned launch in 2018) and Ariel (planned launch in 2026) will add to this number, and begin to probe the environment of these worlds. The Kepler Mission catalogue told us where to look, now we can begin to uncover what alien worlds are truly like. This article was originally published on The Conversation. Read the original article. (Disclaimer: The opinions expressed above are the personal views of the author and do not reflect the views of ZMCL)

Opinion: What are NASA's exo-planets

Aliens could be everywhere. There are at least 100 billion planets in our galaxy alone, and at least 20 per cent of them could be habitable. Even if a tiny fraction of those planets &ndash; less than one percent of one percent &ndash; evolved life, there would still be tens of thousands of planets with aliens in our vicinity. But if we want to figure out where to start looking for these neighbours, we need to understand what they might be like and where they might thrive.

Ultimately, we want to understand as much as possible about an extraterrestrial species before we encounter it. And yet, making predictions about aliens is hard. The reason is simple: we have only one example &ndash; life on Earth &ndash; to extrapolate from. Just because eyes and limbs have evolved many times on Earth doesn&rsquo;t mean they&rsquo;ll appear even once elsewhere. Just because we are made of carbon and coded by DNA doesn&rsquo;t mean aliens will be &ndash; they could be silicon-based and coded by &ldquo;XNA&rdquo;.

However, as my colleagues and I argue in our new study, published in the International Journal of Astrobiology, there is another approach to making predictions about aliens that get around this problem. That is to use evolutionary theory as a guiding principle. The theory of natural selection allows us to make predictions that don&rsquo;t depend on the details of Earth and so will hold even for eyeless, nitrogen-breathing aliens.

Darwin formulated his theory of natural selection long before we knew what DNA was, how mutations appeared, or even how traits were passed on. It is remarkably simple and requires just a few ingredients to work: variation (some giraffes have longer necks than others), the heritability of that variation (long-necked giraffes have long-necked babies) and differential success linked to the variation (long-necked giraffes eat more leaves and have more babies).

Darwin&rsquo;s aliens

In our paper, we use evolutionary theory to make a number of predictions about aliens. First, we argue that aliens will undergo natural selection. This is something often either taken for granted or assumed to be an unknown. We show that there are firm theoretical grounds for believing that aliens will undergo (or have undergone) natural selection.

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Illustration of levels of complexity. A) A simple replicating molecule. B) Cell-like entity. C) An alien. (Others)
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This is because &ldquo;apparent design&rdquo; is what sets life apart from non-life &ndash; such as a single-celled organism from inert rocks. Living things have many intricate parts fine-tuned for the common purpose of replicating the organism. The only way to achieve this apparent design, or adaptedness, the only way to get a life, is through natural selection.

So as aliens are highly likely to undergo natural selection, we can make some predictions about what they will be like. In particular, our predictions are about complex aliens. By complexity, we mean anything more complex than, say, a virus.

Even a bacterial cell has intricate parts that work together to achieve goals, like moving and eating. In other words, most &ldquo;aliens&rdquo; we would be interested in finding, or even able to find, are complex. That&rsquo;s because the only things so simple that they could have arisen without natural selection would be molecules, which are both physically hard to detect and hard to distinguish from the background of inert molecules. They&rsquo;d also be transient &ndash; without natural selection making them fitter they&rsquo;d disappear. Even if we did find them, we probably wouldn&rsquo;t even classify them as life.

Complexity on Earth has arisen through a handful of something called &ldquo;major transitions in individuality&rdquo;. These occur when independent organisms come together to form a new type of individual. On Earth, genes came together to form genomes, single-celled organisms formed multi-cellular organisms, like us. In some rare cases, multi-cellular organisms, like insects, have formed societies that act as &ldquo;superorganisms&rdquo; themselves. These events are rare, and require extreme evolutionary conditions to occur.

We argue that complex aliens will, too, have undergone major transitions, as this is likely the only way to advance beyond a simple replicating molecule. Because the conditions for major transitions to occur are rare, and because they are quite well understood from an evolutionary perspective, this allows us to say something about the makeup of aliens.

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Illustration of a complex alien that comprises a hierarchy of entities, where each lower level collection of entities has aligned evolutionary interests. (Others)
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In particular, just as you and I are made up of cells which are made up of nuclei and mitochondria (the breathing engine of the cell) which are made up of genes, aliens will be a similar nested hierarchy of units. Aliens might not be made of &ldquo;cells&rdquo; as we think of them, but they will be made up of parts which were once free-living, and those parts, in turn, will be too &ndash; all the way down to the aliens&rsquo; hereditary material (whatever it is). Our parts have mechanisms in place that keep all the parts working together to make an organism.

For example, our cells all start as one single cell (the &ldquo;zygote&rdquo;), and this means all our cells are clones, which is why they cooperate to make us. Aliens will have similar ways of enforcing cooperation between their internal parts, at each level of units.

Aliens may not have two legs or any legs at all, but their structure, from an evolutionary standpoint, will be much more familiar than we might have thought. By familiar, I don&rsquo;t mean superficially familiar. They may look, on the surface, wildly different from anything on Earth. But they will be similar on a more fundamental level: their bodies will be constructed in the same way (formerly free-living parts within formerly free-living parts), and they will have undergone a similar evolutionary history (independent organisms cooperating to form new, higher level organisms).

There is much more work to be done to understand what aliens might be like and where we might find them. And the tantalising question &ndash; &ldquo;Are we alone?&rdquo; &ndash; remains unanswered. But, as we have shown, if we&rsquo;re not alone, perhaps we understand more about the makeup of our neighbours than science fiction would have us believe.

This article was originally published on <a href="http://theconversation.com" rel="nofollow" target="blank">The Conversation</a>. Read the <a href="https://theconversation.com/what-evolutionary-theory-can-teach-us-about-the-appearance-of-aliens-86719" rel="nofollow" target="blank">original article</a>.

Image Credit: Shutterstock and Helen S. Cooper

There is much more work to be done to understand what aliens might be like and where we might find them

Aliens could be everywhere. There are at least 100 billion planets in our galaxy alone, and at least 20 per cent of them could be habitable. Even if a tiny fraction of those planets – less than one percent of one percent – evolved life, there would still be tens of thousands of planets with aliens in our vicinity. But if we want to figure out where to start looking for these neighbours, we need to understand what they might be like and where they might thrive. Ultimately, we want to understand as much as possible about an extraterrestrial species before we encounter it. And yet, making predictions about aliens is hard. The reason is simple: we have only one example – life on Earth – to extrapolate from. Just because eyes and limbs have evolved many times on Earth doesn’t mean they’ll appear even once elsewhere. Just because we are made of carbon and coded by DNA doesn’t mean aliens will be – they could be silicon-based and coded by “XNA”. However, as my colleagues and I argue in our new study, published in the International Journal of Astrobiology, there is another approach to making predictions about aliens that get around this problem. That is to use evolutionary theory as a guiding principle. The theory of natural selection allows us to make predictions that don’t depend on the details of Earth and so will hold even for eyeless, nitrogen-breathing aliens. Darwin formulated his theory of natural selection long before we knew what DNA was, how mutations appeared, or even how traits were passed on. It is remarkably simple and requires just a few ingredients to work: variation (some giraffes have longer necks than others), the heritability of that variation (long-necked giraffes have long-necked babies) and differential success linked to the variation (long-necked giraffes eat more leaves and have more babies). Darwin’s aliens In our paper, we use evolutionary theory to make a number of predictions about aliens. First, we argue that aliens will undergo natural selection. This is something often either taken for granted or assumed to be an unknown. We show that there are firm theoretical grounds for believing that aliens will undergo (or have undergone) natural selection. Illustration of levels of complexity. A) A simple replicating molecule. B) Cell-like entity. C) An alien. (Others) × This is because “apparent design” is what sets life apart from non-life – such as a single-celled organism from inert rocks. Living things have many intricate parts fine-tuned for the common purpose of replicating the organism. The only way to achieve this apparent design, or adaptedness, the only way to get a life, is through natural selection. So as aliens are highly likely to undergo natural selection, we can make some predictions about what they will be like. In particular, our predictions are about complex aliens. By complexity, we mean anything more complex than, say, a virus. Even a bacterial cell has intricate parts that work together to achieve goals, like moving and eating. In other words, most “aliens” we would be interested in finding, or even able to find, are complex. That’s because the only things so simple that they could have arisen without natural selection would be molecules, which are both physically hard to detect and hard to distinguish from the background of inert molecules. They’d also be transient – without natural selection making them fitter they’d disappear. Even if we did find them, we probably wouldn’t even classify them as life. Complexity on Earth has arisen through a handful of something called “major transitions in individuality”. These occur when independent organisms come together to form a new type of individual. On Earth, genes came together to form genomes, single-celled organisms formed multi-cellular organisms, like us. In some rare cases, multi-cellular organisms, like insects, have formed societies that act as “superorganisms” themselves. These events are rare, and require extreme evolutionary conditions to occur. We argue that complex aliens will, too, have undergone major transitions, as this is likely the only way to advance beyond a simple replicating molecule. Because the conditions for major transitions to occur are rare, and because they are quite well understood from an evolutionary perspective, this allows us to say something about the makeup of aliens. Illustration of a complex alien that comprises a hierarchy of entities, where each lower level collection of entities has aligned evolutionary interests. (Others) × In particular, just as you and I are made up of cells which are made up of nuclei and mitochondria (the breathing engine of the cell) which are made up of genes, aliens will be a similar nested hierarchy of units. Aliens might not be made of “cells” as we think of them, but they will be made up of parts which were once free-living, and those parts, in turn, will be too – all the way down to the aliens’ hereditary material (whatever it is). Our parts have mechanisms in place that keep all the parts working together to make an organism. For example, our cells all start as one single cell (the “zygote”), and this means all our cells are clones, which is why they cooperate to make us. Aliens will have similar ways of enforcing cooperation between their internal parts, at each level of units. Aliens may not have two legs or any legs at all, but their structure, from an evolutionary standpoint, will be much more familiar than we might have thought. By familiar, I don’t mean superficially familiar. They may look, on the surface, wildly different from anything on Earth. But they will be similar on a more fundamental level: their bodies will be constructed in the same way (formerly free-living parts within formerly free-living parts), and they will have undergone a similar evolutionary history (independent organisms cooperating to form new, higher level organisms). There is much more work to be done to understand what aliens might be like and where we might find them. And the tantalising question – “Are we alone?” – remains unanswered. But, as we have shown, if we’re not alone, perhaps we understand more about the makeup of our neighbours than science fiction would have us believe. This article was originally published on The Conversation. Read the original article. Image Credit: Shutterstock and Helen S. Cooper

What evolutionary theory can teach us about the appearance of aliens

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