Astronomers now regularly discover planets orbiting stars outside the Solar System – they are called planets. exoplanets. But in the summer of 2022 in the Northern Hemisphere, teams working on NASA’s Transiting Exoplanet Survey Satellite (TESS) found some particularly interesting planets orbiting in the habitable zones of their parent stars.
Another reason super-Earths are ideal targets in the search for life is that they are much easier to detect and study than Earth-sized planets. There are two methods used by astronomers to detect exoplanets. One looks for a planet’s gravitational effect on its parent star and the other looks for a brief dimming of a star’s light as the planet passes in front of it. Both detection methods are easier with a larger planet.
Super-Earths are super-habitable
More than 300 years ago, the German philosopher Gottfried Wilhelm Leibniz argued that the Earth was “the best of all possible worlds”. Leibniz’s argument was intended to address the question of why evil exists, but modern astrobiologists have explored a similar question by asking what makes a planet hospitable for life. It turns out that the Earth is not the best of all possible worlds.
Due to Earth’s tectonic activity and changes in the Sun’s brightness, the climate has changed over time from a boiling ocean to freezing cold across the planet. The Earth has been uninhabitable to humans and other larger creatures for most of its 4.5 billion year history. Simulations suggest that the The long-term habitability of the Earth was not inevitable, but a matter of luck. Human beings are literally lucky to be alive.
The researchers created a list of attributes which make a planet very conducive to life. Larger planets are more likely to be geologically active, a feature that scientists believe may promote biological evolution. Therefore, the most habitable planet would be about twice as massive as Earth and would have a volume between 20% and 30% larger. It would also have oceans low enough for light to stimulate life to the bottom of the sea and an average temperature of 25 degrees Celsius. It would have a denser atmosphere than Earth’s which would act as an insulating blanket. Finally, such a planet would orbit a star older than the Sun to give life more time to develop, and would have a a strong magnetic field that protects you from cosmic radiation. Scientists think these attributes combined will make a planet super habitable.
By definition, super-Earths have many of the attributes of a super habitable planet. So far, astronomers have found out two dozen Earth-like exoplanets which are, if not the best of all possible worlds, theoretically more habitable than Earth.
Recently, there has been an interesting addition to the inventory of habitable planets. astronomers began to discover exoplanets that’s gone expelled from their star systemsand there could be billions of them roaming the Milky Way. If a super-Earth is ejected from its star system and has a dense atmosphere and aqueous surface, it could sustain life for tens of billions of yearsmuch longer than life on Earth could persist before the Sun died.
One of the recently discovered super-Earths, TOI-1452b, could be covered by a deep ocean and favor life. Credit: Benoit Gougeon, University of Montreal, CC BY-ND
Survey life on super-Earths
To detect life on distant exoplanets, astronomers will look for biosignatures, by-products of biology detectable in a planet’s atmosphere.
–
