Using measurements of the planet's gravity, astronomers can determine how dense the planet is and how much mass it contains. By comparing the planet's density to the density of pure rock, scientists can estimate the amount of water (or other low-density material) that is present.

The new technique, called "water abundance estimation from transit-timing variations" (WEFTV), is described in a paper published in the journal *Nature Astronomy*. The lead author of the paper, Dr. Rory Barnes of the University of Washington, said in a statement that WEFTV "could help us to identify potentially habitable planets beyond our own solar system."

The discovery of water on other planets is important because water is essential for life as we know it. Liquid water has only been confirmed to exist on Mars and Jupiter's moons, Callisto and Europa, but scientists believe that it could be present on many other planets and moons in our solar system and beyond.

The WEFTV technique could help us to identify those planets and moons that are most likely to harbor liquid water, and thus, life.

WEFTV is not the only technique that astronomers use to search for water on other planets. Other techniques include looking for water vapor in a planet's atmosphere and studying the planet's surface features. By combining these different techniques, astronomers are getting closer to finding planets that could support life.