Enormous water worlds appear to be common throughout the Milky Way. The planets, which are up to 50% water by mass and 2-3 times the size of Earth, account for nearly one-third of known exoplanets.

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Enormous water worlds appear to be common throughout the Milky Way. The planets, which are up to 50% water by mass and 2-3 times the size of Earth, account for nearly one-third of known exoplanets.