LIEGE, BELGIUM — A new international study led by astrophysicist Eric Agol from the University of Washington and involving scientists from the University of Liege has measured the densities of the seven Earth-size planets around TRAPPIST-1 with extreme precision.

According to a press release from the University of Liege, scientists now know more about the densities of these planets than of any other planets outside our solar system, and this provides an important clue as to their compositions.

The study was published on Jan. 22 in the Planetary Science Journal.