Scientists Confirm ‘Terrestrial Nature’ of TRAPPIST-1’s Largest World

Astronomers have recently discovered that the largest of the seven worlds in the TRAPPIST 1 system has an atmosphere that has evolved over time, rather than the one that formed with the planet, confirming its terrestrial nature.

Thanks to observations made with the Hubble Space Telescope scientists were able to lift the veil on the planet and reveal that the atmosphere of TRAPPIST 1g is different from its nascent environment, which means that it is very likely that it is a rocky world similar to others in the system.

An artist's concept of the TRAPPIST-1 worlds, based on available data about the planets' characteristics.
 Image Credit: NASA/JPL-Caltech.
An artist’s concept of the TRAPPIST-1 worlds, based on available data about the planets’ characteristics.
 Image Credit: NASA/JPL-Caltech.

Speaking to, Hannah Wakeford, a researcher at the Space Telescope Science Institute in Baltimore, Maryland said: “This atmosphere is not the one it was born with.”

A natal atmosphere would most likely be one rich in hydrogen, something that astronomer did not manage to see.

Instead, “it’s been changed by different processes,” Wakeford explained.

Scientists believe that atmospheric and geological activity may have played a significant role in the changes.

Using Hubble, Wakeford and colleagues studied TRAPPIST-1 g, the sixth planet from the star.

They had previously probed the atmospheres of the first five planets, identified by the letters b to f, and found that the five planets lack massive atmospheres of hydrogen, a characteristic of gas giants. In turn, scientists believe that they’ve found evidence that the planets are most likely rocky in nature.

Astronomers say that previous studies had not been precise enough to determine if TRAPPIST-1 G had its nascent atmosphere or not.

“G was the last question mark in that,” Wakeford said. “Just like its brothers and sisters, it doesn’t contain its primordial atmosphere. It’s got an evolved atmosphere.”

TRAPPIST-1 g is the largest planet orbiting the star, with estimates that place it at about 1.1 times the mass of the Earth.

Wakeford presented her new findings in at the America Astronomical Society meeting in Seattle.

TRAPPIST-1 has proven to be one of the most interesting solar systems out there.

In 2016, the astronomers using the TRAPPIST Telescope (Transiting Planets and Planetesimals Small Telescope) in Chile announced the discovery of three exoplanets around the star TRAPPIST-1.

Eventually, four more worlds were discovered in the next year, making the total planets orbiting the star seven.

Interestingly, all planets were found to orbit their star within the habitable zone, the region in a solar system where liquid water could exist on the surface.

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