TRAPPIST-1 and Solar System size comparisons. Illustration comparing the sizes of objects in the TRAPPIST-1 system and Earth's Solar System. The ultra-cool dwarf star TRAPPIST-1 (orange, diameter of 162, 793 kilometres) is about the size of the Solar System's largest planet Jupiter (upper left, diameter of 139, 822 kilometres). The Sun (partially shown at bottom right) has a diameter of 1.39 million kilometres. The inset boxes down left show the Galilean moons of Jupiter (Io, Europa, Ganymede and Callisto), the seven planets in the TRAPPIST-1 system (b-h), and the four planets of the inner Solar System (Mercury, Venus, Earth and Mars), all shown to scale. TRAPPIST-1 is 39 light years from Earth, in the constellation of Aquarius. Its planets were discovered in 2015 and 2017. Image published in 2017. |