We still don't know exactly what is causing the bright spots on the surface of Ceres, a dwarf planet in our solar system. However, thanks to a new set of images -- the most detailed yet -- of the planet's surface, we do know that there are a lot more of those little bright spots than first thought.

And NASA experts now have a pretty good idea about what sort of phenomenon is behind them. "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, principal investigator for the Dawn mission, said in a statement.

The new images came from NASA's Dawn spacecraft after it completed its first mapping orbit around Ceres.

[The Curiosity Mars rover caught a stunning blue sunset on the Red Planet]

Image of Ceres spots. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

"The brightest spots within a crater in the northern hemisphere are revealed to be composed of many smaller spots," NASA's Jet Propulsion laboratory said in a statement.

Ceres orbits the sun in the main asteroid belt of the solar system, between Mars and Jupiter. Dawn entered the dwarf planet's orbit in March. It's currently on its way in for a closer, second orbit around Ceres.

[Andy Weir and his book ‘The Martian’ may have saved NASA and the entire space program]

Although there are all sorts of things scientists hope to learn about the early solar system from Dawn's mission, the mystery of the dots has captured quite a lot of attention as the spacecraft produces better and better images of the surface.

First, a crater on Ceres appeared to contain just a single, round speck of brightness. As Dawn approached orbit, a better image of the crater containing the dots showed two distinct spots, not just one. As it moved even closer, scientists noticed that the surface of Ceres is littered with other, less dramatic bright spots.

Now, it's obvious that the single crater containing the brightest spots contains not one, not two, but several of them.

As Dawn approaches even closer to Ceres, researchers will be able to learn even more about the dwarf planet's surface, dots and all.

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March 2: NASA’s historic Dawn mission set to reach the mysterious Ceres on Friday

April 20: New images of Ceres show more mysterious white spots