Two planets that revolve around a small star located 218 light-years distant seem to be of a unique sort that is not comparable to anything that we have in our Solar System. Both of the extrasolar planets have been given the designation of Kepler-138c and Kepler-138d. Both are approximately 1.5 times the radius of Earth, and both look to be wet planets composed of thick, steaming atmospheres and crazily deep seas, all packed around a rocky-metallic interior. Both are approximately the same size as Earth.
Recent research conducted on another globe suggested that it may be a water world; however, further observations are going to be required before this hypothesis can be validated. The researchers say that their findings on Kepler-138’s two marine planets are less ambiguous as a result of their investigation.
Determining the composition of planets that are not part of our Solar System, sometimes known as exoplanets, typically needs quite a bit of investigative effort. They are very far and very faint in comparison to the light of the stars that they circle; direct photographs are very difficult to capture and as a result, are quite uncommon; nonetheless, they do not display a great deal of detail. The chemical make-up of an extrasolar planet can typically be deduced from the exoplanet’s density, which is determined by combining the findings of two separate observations: first, the eclipse (or transit) of the star’s light caused by the planet, and second, the radial velocity, also known as the ‘wobble,’ of the star.
The quantity of sunlight that is obstructed during the transit provides us with information about the size of the exoplanet, which allows us to calculate its radius. The gravitational attraction of the exoplanet causes radial velocity to be induced, which may be seen as a regular but very slight expansion and contraction of the wavelength of the star’s light as it is pushed around by the gravitational tug. The magnitude of this movement may provide information about the mass of an extrasolar planet. You are able to compute the density of an item once you know both its size and its mass.
A gaseous planet, such as Jupiter or even Neptune, will have a density that is on the lower end of the scale. Worlds with a lot of rocks and a lot of metals tend to have greater densities. Earth has a density of 5.5 grams per cubic centimeter, making it the densest planet in our Solar System. Saturn has a density of 0.69 grams per cubic centimeter, making it the least dense planet.
The masses of Kepler-138c and Kepler-138d are estimated to be 2.3 and 2.1 times that of Earth, respectively, based on the measurements of their respective pulls on Kepler-138. Transit data reveal that Kepler-138c and Kepler-138d have radii that are 1.51 times that of Earth. These features, in turn, give us a density that lies midway between a rocky and a gaseous composition – around 3.6 grams per cubic centimeter for both worlds together.
That’s not too far off from the density of Europa, the icy moon orbiting Jupiter, which clocks in at 3.0 grams per cubic centimeter. It just so happens that a liquid global ocean lies dormant behind an ice crust covering the whole thing.
The simulation done by the researchers suggests that water would constitute up more than fifty percent of the volume of the exoplanets, and that it would stretch down to a depth of almost two thousand kilometers (1,243 miles). To put this into perspective, the average depth of the world’s seas is 3.7 kilometers (2.3 miles).
On the other hand, Kepler-138c and Kepler-138d are located a great distance from their star than the Earth is. Even though the star is a tiny red dwarf with a low temperature, the closeness of the two exoplanets would cause them to have temperatures that are far higher than those on Earth. They go around the sun once every 13 and 23 days, respectively, according to their orbital periods. According to the experts, this indicates that the seas and atmospheres on these planets are very unlikely to resemble our ocean in any significant way.
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