For years, scientists have known that Earth is something special. Its distance from the sun allows for the perfect amount of light and heat to enter the atmosphere, giving us the perfect temperature and energy to sustain life. While the debate about the origin of said life still continues, no one can deny that Earth – and the organisms on it – is markedly different from the rest of our observable universe.
But what if there was a planet out in the universe that was like ours?
It’s difficult to get a planet that is exactly like Earth; the same revolutionary steps as Earth would be difficult to recreate. But, there is a chance of finding a planet situated in a region scientists call the “habitable zone.” This zone is the area surrounding a star that allows a planet in its orbit to sustain liquid water on its surface. You can usually tell where the habitable zone is based on a star’s heat emittance. Water on the surface of a planet can be telling of a planet’s ability to sustain life, especially life from Earth.
One of the closest exoplanets that scientists found is only a little bit more than four light years away. It’s a planet orbiting the smallest member of the star system Alpha Centauri, Proxima Centauri. After the sun, it’s the closest star we can travel to. Dubbed Proxima b, the exoplanet can complete a single orbit around its sun in 11 days; it’s much closer to its own star than Mercury is to the sun.
However, while scientists have found this planet in a habitable zone and saw that its size was similar to Earth – only 1.3 times bigger! – the prospect of actually finding life similar to our own, or situating human beings on its surface, seems a little distant. The temperature and amount of light the planet receives may be similar, but there are other factors that are unaccounted for.
We do not know, for example, whether these planets also receive harmful electromagnetic waves like X-rays and UV rays. Nor do we know whether this planet can sustain a proper atmosphere, which is important for sustaining life, as it is a large regulator of temperature and pressure. Proxima b orbits a red-dwarf star — which is smaller than the sun and doesn’t produce as much heat — is a lot more hyperactive than the G dwarf star our sun is. Solar flares from the red-dwarf can hit Proxima b and cause damage to its surface. Ultraviolet radiation becomes a problem when the atmosphere is burned away; it takes molecules like hydrogen, oxygen, and nitrogen (very important parts of the Earth’s atmosphere and our own living organisms) and ionizes them, allowing them to escape the planet’s gravity and into space. Without oxygen and hydrogen, water supply would be quite minimal.
So the search continues; scientists have learned that just because a planet is in a star’s habitable zone doesn’t mean it’s able to be habituated. While Proxima b is not an example of an exoplanet that is ready for human colonization, or even finding other forms of life, it is a guide for scientists to focus on when it comes to learning and exploring our endless universe and all that is in it.
