The new moons, which were named Mab and Cupid, bring the total number of satellites orbiting Uranus to 27.
Astronomer Mark Showalter of the SETI Institute and his colleagues were not looking for new moons or rings when they submitted a proposal to take deep exposures of the planet with Hubble’s most advanced optical camera. Rather, they planned to study the 11 previously known rings and several moons embedded within them.
Once they saw the new moons, they re-examined images that the Voyager 2 spacecraft took when it flew by Uranus in 1986. The two moons are clearly there, but no one recognized them at the time.