No one is really sure. Scientists have known since 1781 that Uranus is one of the planets in our solar system. However, they are still finding new moons orbiting this faraway planet. Telescopes and other scientific tools are constantly being improved.
More powerful telescopes allow scientists to see all the planets more clearly, including Uranus.
Then in 1997, a group of astronomers in California spotted two new moons. They were looking through the Hale telescope at Palomar Observatory. With the help of its huge lens, the astronomers were the first to notice the faint glow of these two moons. They have now traced the paths of the moons around Uranus. The paths are less circular than those of the other 15 moons.