Are Super-Earths Actually the Best Places to Search for ET?

Super-Earths may be the best place to search for extraterrestrial life due to their long-lived magnetic shields, according to a recent study. Scientists had previously thought that Earth-sized rocky exoplanets, meaning planets located outside of our own solar system that are of a similar size and composition of our own Earth, might make the best places to search for ET. However, this newest study seems to indicate that super-Earths, meaning rocky exoplanets ranging from 2 to 10 times larger than earth, may make even better environment to foster life.


Ever since scientists first spotted a planet outside of our own solar system, debates have raged about which of these exoplanets may be home to non-human life. Since the majority of exoplanets found thus far are gas giants like Jupiter or Saturn, the odds of finding life similar to what we know here on Earth on those gaseous worlds is incredibly slim. However, a significant number of the exoplanets spotted by NASA using Hubble and the Kepler planet finder mission are of a rocky nature, with the majority of these landing in the super-Earth category.

Now, a group of researchers is looking at the dynamics of iron, which is thought to be at the core of most such planets, and how it may relate to a planet’s habitability.


Published in the journal Science, a team of researchers looked specifically at the melting point of iron under extreme pressure conditions like those found at the cores of planets. This is significant because on Earth, our iron core rotates to create a magnetic shield known as our magnetosphere around the planet, which protects life from deadly solar radiation pouring off of our Sun.

“The discovery of more than 4500 extrasolar planets has created a need for modeling their interior structure and dynamics,” the study abstract reads. “Given the prominence of iron in planetary interiors, we require accurate and precise physical properties at extreme pressure and temperature.”

To conduct their experiments, the researchers employed a set of high-energy lasers at the National Ignition Facility to zero in on the melting point of iron up to 1000 gigapascals, which they note is three times the pressure fond at Earth’s inner core.

These measurements allowed the team to model the “dynamo-action” of the melted iron, which is critical to the magnetic shield’s formation. And to their surprise, they found that Earth’s magnetic shield won’t last nearly as long as those on super-Earth sized planets.

“We find that terrestrial exoplanets with four to six times Earth’s mass have the longest dynamos,” the researchers concluded, “which provide important shielding against cosmic radiation.”


Precious few of the exoplanets already spotted by astronomers are similar in size to Earth, possess a similar material make-up, and exist within their host star’s habitable zones, meaning an orbit altitude where liquid water can exist on that planet’s surface. However, super-Earths are much more common.

So, as the James Webb telescope is nearing its final destination where it will begin hunting the cosmos, researchers back here on Earth are adding to the list of potential places to search for E.T, seemingly increasing the chances of finding the first signs of life outside of our planet.

Follow and connect with author Christopher Plain on Twitter: @plain_fiction