But the hope is that by studying the atmosphere of all these planets in the habitable zone, we might find some of the biological signatures of living things.
The exoplanet takes 25 days to orbit its star and despite being 10 times closer to LHS 1140 than Earth is to the Sun, it only receives about half the "sunlight" that Earth does.
Astronomers estimate the age of the planet to be at least five billion years, just a little older than Earth. And it may even have an atmosphere. Three of the planets are in the Goldilocks zone, though all of the TRAPPIST-1 planets are believed to be rocky. The next largest planets in our solar system are gaseous, like Uranus and Neptune.
"This is the most exciting exoplanet I've seen in the past decade", lead author and Harvard staffer Jason Dittmann said in the ESO statement.
Super-Earths exist in between.
Since the star it orbits is quite small and relatively close to us, it may be possible for current telescopes and those now under construction to determine if the planet has an atmosphere.
In the constellation Cetus, it is 39 light years or 230 trillion miles away.
A Harvard team was first to spot the tell-tale dips in light from the star.
The star that LHS 1140b orbits is both small and faint. When red dwarf stars are young, they emit radiation that can damage the atmospheres of planets around them. Then, to much fanfare, NASA announced the discovery of not one, not two, but seven Earth-sized planets in the TRAPPIST-1 system, which lies just 39 light-years from Earth. That is proportional to the planet's mass.
The researchers have also weighed the planet to be 6.6 times the mass of Earth, showing that it is dense and likely has a rocky composition. The exoplanet had a "hellish" past.
But if the planet can shield and hide its water source from this heat, it would be saved, Dittman said. This is also promising in the hunt for potential life. Hot, molten lava can trap and hold onto water and other gases, Dittman said.
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The boundaries of the habitable zone are critical. Too close, and the object will burn. Life would also be unsustainable if it's too thin and wispy like Mars, with all the water locked up as ice. Just the right distance and equilibrium is achieved.
As LHS 1140 is much smaller and cooler than our own star, it doesn't throw out anything close to the levels of radiation that our Sun is capable of emitting.
The first hint of the planet's existence was gathered by Harvard's dedicated red dwarf survey, MEarth. "We will need to learn about the planet's atmosphere before we can conclude on whether life could be harboured on the planet", Dittmann said.
If signs of life are found in the planet's atmosphere, it might be possible to send a probe to explore further.
In future, observations with the Nasa Hubble Space Telescope will assess exactly how much high-energy radiation is showered upon LHS 1140b.
Geneva University says its HARPS planet searcher instrument was key in confirming the presence of the super-Earth.
"We don't have atmospheric measurements right now, but the star behaves nicely so that it's not ruling out anything", says Dittman. "This is the one we've been hunting for all these years!"
Julien de Wit, one of the researchers that discovered the TRAPPIST-1 planets, agrees.
He is excited about eventually answering the question of whether or not we're alone in the unvierse. "In the search for signs of habitability, signs of life elsewhere, the more the merrier". "We found a planet that we can actually study that might be actually Earth-like".
The new planet was found using eight small telescopes in Chile and help from an amateur planet-hunter, Charbonneau said. "We plan to search for water, and ultimately molecular oxygen".