If a cataclysm strikes our planet, then we'd better have an Earth backup plan somewhere in the universe. Whether we need to find a new home for our species because something has destroyed our original home, or simply because we are desperate to find signs of life on other planets, other planets have always been a source of human charm.
But have we found what we are looking for? Today we're going to answer this remarkable question: Have we discovered Earth 2.0?
The concept of "Earth 2.0" usually refers to an alien world that is already similar to Earth, rather than a world that can be similar to Earth with some adjustments.
While planets within our solar system, such as Venus and Mars, are similar to Earth in size, location, and composition, we can't live safely on top of them without completely enclosing ourselves in high-tech, customized habitats, or dramatically altering the planets themselves through terraforming.
So if we want to have a true "home away from home", then we need to look even further afield than Jupiter and Saturn (even if these two ice-covered planets will one day become human colonies); In fact, we need to expand our horizons to completely different galaxies.
It is estimated that there are 100 billion planets in the Milky Way. And, according to some NASA projections, at least 40 billion of these planets may be planets the same size as Earth, 11 billion planets are planets the same size as Earth, and 11 billion planets orbiting sun-like stars and the same size as Earth.
Considering that we currently have only one confirmed habitable planet — our own Planet , and potentially 11 billion other planets to explore — this undoubtedly makes us more likely to find a second habitable planet.
We call all planets discovered outside the solar system "exoplanets," and the first exoplanet was discovered in 1992. This sounds crazy now, but until then, we had been assuming that planets existed elsewhere, rather than having conclusive evidence that they did exist. These first groundbreaking exoplanets, located in the PSR B1257+12 galaxy, were detected by analyzing irregularities around nearby pulsars, a pulsating neutron star.
Unfortunately, for these particular planetary worlds, their radiation is too intense to support life, but their discovery has prompted scientists to look for more planets similar to them. In 2009, NASA launched the Kepler Space Telescope solely to find planets orbiting other stars, one of the biggest moves to discover exoplanets.
While the Kepler program suffered some problems during the flight, it eventually succeeded in achieving its target task and ran for nine years before running out of fuel in 2018. During that time, it detected more than 2,600 planets and 500,000 stars, meaning that in less than 30 years, we've gone from zero proven exoplanets to thousands. Kepler works by detecting "transits" in distant stars,[2] the phenomenon in which the light they emit is obscured by planets moving in front of them. Prior to that, Kepler allowed us to build a comprehensive "space map," and because of that, Kepler discovered one of the best candidates for Earth 2.0 in 2015, Kepler-452b, often referred to as "Earth's cousin."
It is a super-Earth, predicted to be 5 times the mass of our Earth, located in a habitable zone about 1400 light-years away from its star system. It's not close enough that we can go there and see for ourselves what planet we're going to face... But it's not far away, and our most advanced telescopes, like the Hubble Space Telescope, could have looked at it better, but it hasn't been used to investigate 452b yet, and there are precedents for other schemes. This means that if we can examine it more closely, scientists are now completely inconclusive on what we will see. We're not even sure if it's a rocky planet like Earth or if it's made of gas.
The SETI Institute, the group responsible for the "search for extraterrestrial intelligence," has been trying for some time to detect an infinite electrical signal from 452b, hoping that it could be the source of extraterrestrial life, but to no avail. This confusion has left some skeptical about whether 452b even exists — though a seti study did estimate that the probability of the planet's actual existence was between 16% and 92%, a sizable margin of error. Even so, scientists and star observers alike are well aware that there are billions of worlds to choose from in the search for a "second Earth," and it would be inappropriate to place all our efforts on a distant, controversial planet, at least thousands of other planets we can and are working on.
The closest Earth-like planet outside our solar system is Proxima B. It's only four light-years away, which sounds much easier to reach, but there are still some problems. The main problem is that the star around Proxima B is a red dwarf. Red dwarfs are the most numerous stars in the universe, but we're not quite sure if the planets surrounding red dwarfs are habitable. Red dwarfs are much darker than yellow stars like our sun, so theoretically any habitable planet would need to be closer to the star... This may not be a serious problem, unless a planet is so close to the star that it maintains a tidal lock with the star.
This is not necessarily the case with Proxima B, but we can't be sure at this time whether Proxima B is at some distance from its star, just like Earth did. But what is certain is that if any planet is tidally locked to the star it orbits, then it can no longer be considered "Earth 2.0"... Because one side will always turn its back on its star, in a sense, the two sides of the planet will be two completely different worlds! Another oft-cited exoplanet is K2-18b, which is 120 light-years away and was also discovered by the Kepler telescope. It is quite optimistic about two things: one is that it is much closer to us than 452b, and the other is that it is predicted to have a temperature situation similar to that of Earth.
But it's also a planet orbiting a red dwarf star, and it's orbiting very fast — it can complete a full orbit every 33 days, and the year there is roughly equivalent to a month on Earth. Although scientists believe that habitable planets are indeed possible in red dwarf star systems, and in fact, red dwarf star systems may even have an advantage over the solar system because red dwarfs have a fairly long lifespan, it is still too early to consider K2-18b as "Earth 2.0".
Imagine how drastically it would change if our planet had only 33 days a year (if you didn't realize it yet)! With all this in mind, only Kepler-186f has the potential to become a "second Earth." Many scientists believe it may be the best candidate to date. The Kepler telescope has discovered the planet, which is about 550 light-years away, but it happens to be in the habitable zone of its star (another red dwarf), and it is not a super-Earth; scientists believe that its radius is only about 700 miles larger than the radius of our Earth, and it is most likely a solid planet.
Since its discovery in 2014, NASA confidently calls it "the first Earth-sized planet in a habitable zone." In the eyes of many, this is still our best bet Kepler-186f is farther from its "sun" than we are from the sun. That means the weather there will be darker and colder, but not too severe, not cold enough for us to survive.
If, one day, we find a way to span 550 light-years between Earth and it, we'll actually be able to reach another home beyond Earth, at least compared to other planets we currently know. The only thing missing is someone or something who can share it.
Because, if a planet is really Earth 2.0, doesn't that mean the planet is already supporting its own life?
If that's the case, if it already has a natural population, then we have a whole bunch of problems at hand. Because, while we may be very tempted to visit or migrate to a world where we don't need to spend time, money, and energy transforming it on a large scale by our standards, is it morally right to do so? Extraterrestrial exploration can even find gold before we arrive, find undisputed signs of intelligent life, but what if intelligent life there doesn't want to be disturbed? Imagine, conversely, if there were an intelligent species living in other worlds in the universe that were trying to make their home on other habitable planets that happened to be ours.
Can we really accept the sudden appearance of an alien race to rename our homeland a "second version" of their former homeland? Probably not! So finding Earth 2.0 and actually planning to migrate there have two very different prospects – the second could cause harm to ecosystems that have never been requested or hoped to be disturbed. This is an upcoming ethical debate.
On the one hand, discovering other planets (like Earth or not) helps us better understand the universe; on the other hand, rather than finding a second home for humanity, we should commit to making Earth (our Planet) a better place before we abandon it. In either case, there are a large number of exoplanets, and statistically at least some of them should be able to conceive life and even accurately simulate conditions on Earth. Despite technical limitations and ethical controversies, the search for Earth 2.0 is ongoing. The list of candidate planets is getting longer and longer.
By:..., little wooden drag, threonine, rainbow