The lead author Ryan Cloutier, from the University of Montreal, stated that being able to cover the mass and density of K2-18b was enormous but to find a new exoplanet was fortunate and equally exciting. Both the planets revolve around the red-dwarf star K2-18, which is 111 light years from Earth.
The data set used by the researchers came from the High Accuracy Radial Velocity Planet Searcher (HARPS) using the European Southern Observatory's 3.6m telescope at La Silla Observatory, in Chile. By measuring the radial velocities of stars, which can be influenced by the presence of planets around those stars, HARPS can allow for the detection of the planets around the stars.
Researchers from the University of Texas and the University of Montreal found that the planet is probably mostly rocky with a gaseous atmosphere - a similar composition to Earth.
The newly discovered planet is closer to its star, meaning it is likely to be too hot to support life.
However, not much was known about the exoplanet earlier, particularly about its composition, which is the reason researchers from the University of Texas and the University of Montreal chose to find out whether K2-18b is a rocky scaled-up version of Earth or a gassy object like Neptune.
"It wasn't a eureka moment because we still had to go through a checklist of things to do in order to verify the data", Cloutier said.
"With the James Webb Space Telescope (JWST) we can probe the atmosphere and see whether it has an extensive atmosphere or it's a planet covered in water", Mr Cloutier said, which means they could determine if the planet is more like Neptune or the Earth that we know and love.
To do this, they first figured out the planet's mass, using radial velocity measurements of the K2-18 star and a machine learning calculator.
It was while looking through the data of K2-18b that Cloutier noticed something unusual.
"If you can get the mass and radius, you can measure the bulk density of the planet and that can tell you what the bulk of the planet is made of", Cloutier said.
Study co-author Professor René Doyon, also from the University of Montreal, added: "There's a lot of demand to use this telescope, so you have to be meticulous in choosing which exoplanets to look at". James Webb Space Telescope is created to observe some of the most distant events and object in the cosmos in the most exceptional clarity.
"K2-18b is now one of the best targets for atmospheric study, it's going to the near top of the list".