Seven rocky planets orbiting the red dwarf star Trapist-1, about 40 light-years away, have similar densities. Similar features give hints about their creation.
Trapist-1 is the center of the largest Earth-sized planets in a single galaxy. According to previous calculations, the planets are approximately the size and mass of Earth, so they must be rocks or terrain, in contrast to the gas-dominated Jupiter and Saturn. According to The New Paper, published in the Journal of Planetary Science, it measures the most accurate concentration of any exoplanet ever.
More precise scientists know the density of a planet and can place more limits on their structure. The densities of the eight planets in our own solar system vary widely. Seven TRAPPIST-1 planets have similar densities – values should not exceed three percent.