Scientists had hoped sharper images of Ceres and its mysterious bright spots would provide some clarity as to their nature and origin, but they remain befuddled.

Researchers are fairly certain something in the bottom of a large crater is reflecting the sun's rays, but they still can't verify exactly what the reflective material is.

NASA's Dawn probe has spent the last several weeks orbiting and mapping Ceres, the closest of the solar system's five dwarf planets. In a May 16 photo, newly released by NASA, Dawn's camera reveals the bright spots in impressive detail. Still, scientists aren't sure what they are -- or why they're only in one of the dwarf planet's surface depressions.

"Dawn scientists can now conclude that the intense brightness of these spots is due to the reflection of sunlight by highly reflective material on the surface, possibly ice," Christopher Russell, lead scientist on the Dawn mission and a researcher at the University of California, Los Angeles, said in a press release.

While researchers' best guess is ice, it's unclear whether the images are showing a slick sheen, like the surface of a lake, or something more dynamic, like an ice geyser.

The probe is currently propelling itself to a wider orbit, but subsequent orbits will see the spacecraft move even closer to the dwarf planet's surface -- maybe then giving scientists more answers than questions.