A planet 124 light-years away may have habitable environmental conditions, USA Today reported. The planet in question, which is several times the size of Earth, was first discovered in 2015. Multiple factors must align to support our species.
According to the USA Today article, the new Earthlike celestial body is called a “Super Earth” because it has a mass larger than Earth but smaller than Neptune. Additionally, it is an exoplanet, which, according to NASA, is any planet that orbits a star different from our own. The exoplanet has been designated K2-18b by the scientific community.
“The planet is 124 light-years away in the constellation Leo,” the article said. “This ‘Super Earth’ is the right distance from its star to conceivably harbor life.”
In order for an exoplanet to have truly habitable conditions, many different needs must be met on, beneath, and above its surface.
The most obvious criterion for making another planet habitable is an adequate supply of liquid water, since all known living creatures depend on it in one way or another. However, water alone won’t sustain us, and other key components of life on Earth come up often in scientific debate.
“Some have argued that in order to be truly habitable, a planet needs to be geologically active, with volcanoes and continental drift, similar to what we have on the Earth,” said Dr. Joshua N. Winn, Professor of Astrophysical Sciences at Princeton University. “This is because on Earth, those geological processes are important in recycling carbon atoms from dead organisms back into the atmosphere.”
Dr. Winn said that it’s possible another planet would require some kind of protection from its star’s ultraviolet ionizing radiation. Here, he said, Earth’s magnetic field and the stratosphere’s ozone layer provide that protection.
“Some have even argued that having a big massive moon is crucial for life,” he said. “The reason is that without our own Moon, the direction of Earth’s spin axis would tumble around erratically over millions of years due to the gravitational pulls from other planets in the solar system. So the Earth’s climate would have been too chaotic for life to evolve.”
The Water of Life
Dr. Winn said those arguments may come from “a parochial view.” They may be ideal, but not necessary. However, it’s hard to argue against a water supply, which in turn requires a planet of proper size and atmosphere.
“We want the planet to have a solid surface—a platform for the liquid water to form oceans—so this excludes gas giants like Jupiter and Saturn and also gas-rich planets like Neptune and Uranus,” Dr. Winn said. “To have a solid surface, an exoplanet should be no more massive than around six times the mass of the Earth and no bigger in diameter than about twice the size of the Earth.
“That’s because planets with larger dimensions always seem to have thick, gaseous atmospheres; so the surface would be smothered at an extremely high pressure, or there might be no surface at all.”
Temperature also factors in, which relates to the distance of the planet from its star as well as the previously mentioned atmospheric conditions protecting the surface from the star’s radiation.
However, it all starts with water.
Dr. Joshua N. Winn contributed to this article. Dr. Winn is the Professor of Astrophysical Sciences at Princeton University. After earning his Ph.D. in Physics from MIT, he held fellowships from the National Science Foundation and NASA at the Harvard-Smithsonian Center for Astrophysics.