NASA's Dawn spacecraft has done it again. The prolific probe has captured its best image yet of the strange bright spots on the dwarf planet Ceres.

This photo is just the latest in a series of "best bright spot photos yet" as Dawn moves into a closer orbit around Ceres, the largest body in the main belt of asteroids between Mars and Jupiter. The new image shows off the reflective spots seen in one of Ceres' many craters by Dawn earlier in the probe's mission.

Scientists haven't yet pinpointed the cause of the bright spots, but NASA wants to know what you think they might be. The space agency has opened a voting pool, asking members of the public to decide what they think is causing the reflectivity. Voting choices include "ice," "volcano," "geyser" and "salt deposit," plus a catch-all "other" category.

(At the moment, "other" is winning the poll, perhaps because "alien colony" wasn't listed as one of the options.)

Vote for your favorite possible cause for the bright spots on Ceres. Image: NASA

Some researchers are leaning toward "ice" as a likely candidate for the cause of the spots. They know that the patches are caused by some kind of "highly reflective material" on the surface of the dwarf planet, and it could be frozen water, Dawn principal investigator Christopher Russell has said.

The new image of the reflective patches was taken on May 16, as Dawn flew about 4,500 miles (about 7,200 kilometers) from the surface of the cosmic body. Dawn will stay in that orbit until June 30, when it will go in for a closer look at the planet from lower orbits, NASA said.

Dawn became the first human-made probe to start orbiting Ceres in March 2015. Before moving on to the dwarf planet, Dawn explored the large asteroid Vesta also located in the main belt of asteroids.