Despina is a tiny moon of Neptune. A mere 148 kilometers across, diminutive Despina was discovered in 1989, in images from the Voyager 2 spacecraft taken during its encounter with the solar system's most distant gas giant planet. But looking through the Voyager 2 data 20 years later, amateur image processor and philosophy professor Ted Stryk discovered something no one had recognized before — images that show the shadow of Despina in transit across Neptune's blue cloud tops.
Pluto, a distant icy dwarf planet, orbits the Sun 29 times farther out than the Earth and has estimated surface temperatures of -380 degrees Fahrenheit (-229 degrees Celsius). These frigid temperatures are far too cold to allow liquid water on Pluto's surface. Its location and small size make it very difficult to observe; however, with NASA's New Horizons mission slated to reach the distant world next year, scientists hope to map Pluto and its moons in great detail.
Current models predict one moon in particular, Charon, is of great interest to study. The models indicate Charon has surface fractures, indicative of a possible subsurface ocean. Further analysis is needed to determine in the moon's interior is warm enough to support liquid water.