There are mysterious "super-Earths" all over the galaxy

 Our solar system is peculiar.

Yes, there are strange worlds out there: moons harboring oceans, a desert orb that once teemed with water, and, of course, a planet brimming with strange, tentacled life. Yet our cosmic neighborhood is also unusual for what it doesn't have.

It's a golden age in the discovery of worlds beyond our solar system, called exoplanets. NASA has confirmed well over 5,000 of these planets. Among the most prevalent is a class of worlds dubbed "super-Earths." They are worlds ranging from some 30 to 70 percent bigger than Earth. They can be rocky (like Earth) or largely composed of thick, swirling gases. Or both. Around one-third of exoplanets discovered so far are super-Earths, meaning they're awfully common in other solar systems.

The back-of-the-envelope math is compelling. There are likely over a trillion exoplanets in our Milky Way galaxy alone. So as far as we know, the universe must teem with super-Earths — and some of them may be habitable, meaning they harbor conditions that could sustain life, if it exists there.

"They are indeed very exciting planets," Renyu Hu, an exoplanet researcher at NASA's Jet Propulsion Laboratory, told 

In 2022, for example, NASA announced the discovery of planet LP 890-9 c. It checks a lot of boxes for potential habitability. It's rocky, about 40 percent larger than Earth, and orbits in the "habitable zone" of its solar system, meaning a region where liquid water could exist, though it may be a cooler world than Earth. But what it's like there remains largely elusive.

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 contain an ocean many times the size of Earth's. Fortunately, both new and forthcoming giant telescopes will enable scientists to peer into the atmospheres of these mysterious, distant worlds.

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 found over 240 confirmed planets so far, along with thousands of other candidates.

Once exoplanets are discovered, astronomers can look deeper. Today, the James Webb Space Telescope, the most powerful space telescope ever deployed, is equipped with instruments that can detect what exoplanet atmospheres are composed of. Earth, for example, contains bounties of nitrogen and oxygen, along with trace amounts of gases like carbon dioxide (though this carbon dioxide has a momentous influence on the climate).

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 space, and ultimately into instruments called spectrographs aboard the Webb telescope. They're essentially hi-tech prisms, which separate the light into a rainbow of colors. Here's the big trick: Certain molecules in the atmosphere absorb specific types, or colors, of light. So if that color doesn't show up in the spectrum of colors observed by a Webb spectrograph, that means it got absorbed by (or "consumed" by) the exoplanet's atmosphere. In other words, that element is present in that planet's skies.

Astronomers would like to point Webb at the super-Earth discussed above, LP 890-9 c. It holds promise to be a habitable world.