Planet Ceres is one of the largest dwarf planets orbiting the asteroid belt between planets Jupiter and Mars. Researchers are studying every bit of the planet in hopes of under covering more about the solar system. One of the ways to do it is to study Ceres' craters. Yet, these appear to be missing.

When NASA's Dawn spacecraft orbited planet Ceres, scientists were shocked to see that its surface was smooth. This finding does not make sense as the dwarf planet should have been subject to the same rate of asteroid impacts along with other planets on the belt.

In a collision model, researchers' state there should be around 10 to 15 craters sized 250 miles in diameter on the planet. Surprisingly, these craters can't be seen.

"Ceres is thought to have formed at the dawn of the solar system, some one to ten million years or so after the onset of formation," stated Simone Marchi, the lead researcher at Southwest Research Institute. "Thus, Ceres is a witness to the tumultuous early days where collisions were much more frequent and violent than today. Thus, it points to something special about Ceres, something that we could not have guessed."

Using computer models and data taken from the Dawn spacecraft, Marchi along with his colleagues have come up with the conclusion that the "peculiar composition and internal evolution" of planet Ceres caused the craters to mysteriously disappear.

"It is as though Ceres cures its own large impact scars and regenerates new surfaces, over and over," explained Marchi.

Researchers are still left in the dark as to how the dwarf planet managed to smoothen out its craters. Reportedly, they've come up with two ideas: one, the icy layer had smoothened out the craters over time; two: ice, active volcanoes had spewed water that had smoothened the surface of the planet.