Water vapor has been detected around Ceres, one of the largest asteroids in our solar system, by the European Space Agency's infrared Herschel space telescope before it was decommissioned last year.
Ceres, now classified as a dwarf planet, has long been thought to have rocky core and an icy outer layer. While there is no certainty as to where this water is coming from, the ESA suggests this could be due to the sublimation of ice -- the melting of ice from solid state directly to vapor form. The quantity of gas being ejected is not large -- 13 pounds every second -- but is undeniably water vapor.