Our solar system is peculiar.
Yes, there are strange worlds out there:
It’s a golden age in the discovery of worlds beyond our solar system, called
The back-of-the-envelope math is compelling. There are likely over a
“They are indeed very exciting planets,” Renyu Hu, an exoplanet researcher at NASA’s Jet Propulsion Laboratory, told Mashable.
In 2022, for example,
What’s in its atmosphere? Are any super-Earths truly like Earth? “We don’t know a lot about super-Earths, because we don’t have one in our solar system,” Chris Impey, a professor of astronomy at the University of Arizona, told Mashable.
“They are indeed very exciting planets.”
Another super-Earth discovered in 2022 may
Revealing mysterious super-Earths
Finding new worlds is hard. Specialized telescopes like NASA’s TESS space telescope must stare at stars and look for minute changes in their brightness. A star dimming might mean that a planet passed in front of the star, which could lead to the discovery of a new world. TESS has
Once exoplanets are discovered, astronomers can look deeper. Today, the
But even the nearest planet is trillions of miles away. How can a telescope deduce what’s happening on such a far-off super-Earth? Again, astronomers rely on starlight. When a planet transits in front of a star, light passes through the exoplanet’s atmosphere, through
Credit: NASA / JPL-Caltech
Importantly, Webb will get much-needed exoplanet-sleuthing help later this decade. Of note, the aptly named “
Though we’ll learn bounties more about super-Earths in the coming decades, lots will remain elusive. We’re inherently limited by our address in the cosmos. The Webb telescope, for example, can only view exoplanet atmospheres that it can see transiting in front of their stars. Webb needs the perfect angle to see this happen, but our telescopes aren’t often at the right angle. A typical planet’s transit around the most common type of star in our galaxy (called a red dwarf) has just a two-percent chance of being detectable, explained Ravi Kumar Kopparapu, an exoplanet researcher at NASA’s Goddard Space Flight Center.
The closest planet to us, Proxima Centauri b, is a super-Earth discovered in 2016. Its existence is known from
“We can’t know much about it until we have more powerful telescopes,” Kopparapu told Mashable.
Life on habitable worlds?
Might some super-Earths truly be habitable, meaning life could potentially dwell there? “That is one of the fundamental questions we want to know,” said Kopparapu.
But if a super-Earth is indeed habitable, that doesn’t mean there’s life there. Not nearly. “A habitable planet can be habitable but not inhabited,” Kopparapu emphasized.
Impey, of the University of Arizona, suspects there are quite a few habitable super-Earths. Why? They have masses larger than Earth, giving them better odds at holding onto a thick atmosphere which protects them from harmful radiation and UV rays, he noted. Super-Earths may also hold onto bounties of water. “Water is not a rare ingredient in the cosmos,” Impey added.
“Nature can fool us in many different ways.”
NASA’s Hu is especially interested in super-Earths that are “cold.” This doesn’t imply that they’re snowballs. It means they’re not scorched by close orbits around their star (many exoplanets are discovered close to their stars, like
Conversely, some exoplanets may have steam atmospheres, explained Kopparapu. Torrid climes could have evaporated this water from the surface. Such a world is indeed hot, but perhaps life could dwell in some regions, or subterranean places, on or in the planet’s rocky surface. After all, life on Earth thrives in sweltering environments around underwater volcanic vents, and in
Credit: Benoit Gougeon / Université de Montréal
Actually identifying life on a distant super-Earth, however, is a different, profoundly challenging story. Indeed, we can journey to remote places on Earth and find life thriving in extreme places, such as
From trillions and trillions of miles away (many light-years), an abundance of evidence must come together to support any assertion that a super-Earth
“We have to be really careful,” Kopparapu emphasized. “Nature can fool us in many different ways.”
Even on the closest planet to Earth,
In the search for habitability on super-Earths, astronomers may ultimately discover that few are actually like Earth. Maybe they’re dominated by different gases, or don’t have rocky lands jutting out from water oceans. And would that be such a bad thing?
“I would be disappointed if they’re Earth-like,” said Kopparapu. “We want to explore strange new worlds.”