Its event horizon--theboundary at which nothing, not even light, can escape the monster’s gravitationalpull--is four times as large as the orbit of Neptune,our sun’s outermost planetarysatellite.
IF OUR solar system holds so many remarkable moons, then what strange satellite worlds might we find among the billions of planetary systems in the Milky Way?
If our solar system holds so many remarkable moons, then what strange satellite worlds might we find among the billions of planetary systems in the Milky Way?