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Scientists detect two water worlds 218 light years away

Why in the News?

According to a new study, a team of astronomers have found water worlds, two exoplanets orbiting a red dwarf star.

What are the Key Findings?

• About the Exoplanets:
  • These extraterrestrial worlds, known as Kepler-138c and Kepler-138d, were spotted by NASA’s Hubble and the now-retired Spitzer space telescope.
  • It is the first time that planets have been positively recognised as water worlds, a category of planet that astronomers have long suspected to exist.
  • The exoplanets are unlike any planets in our solar system and are found in a planetary system 218 light years away in the constellation Lyra.
  • An orbit of the new planet takes 38 days to complete.
  • It is in the habitable zone, which means that it is on an orbit where the star provides exactly the appropriate amount of heat for liquid water to exist.
• Findings:
  • Ingredients in Kepler-138c and d are heavier than hydrogen or helium but lighter than rock (rocky planets like Earth) (gas-giant planets like Jupiter).
  • This indicates the presence of water because it should make up up to half of the mass of the twin planets.
  • They calculated that the two have a mass that is twice as large and a volume that is three times that of Earth.
  • They are also bigger counterparts of Jupiter’s moon Europa and Saturn’s moon Enceladus.
  • The twin exoplanets’ density is lower than that of Earth but similar to that of Enceladus and Europa.
  • Smaller than Earth planets have often had stony properties up until now.
  • These twin planets of the same size and mass are more massive than Earth but lighter than ice giants Uranus and Neptune.
  • But they are different from the planets in our solar system, which is chiefly composed of rocky planets like Earth and gas giants like Jupiter.
• Significance:
  • It can help researchers address the knowledge gap and find more water worlds in the future.