NASA's Dawn Closer to Ceres But Miles Away From Demystifying Bright Spots

Though it inched closer to Ceres, Dawn spacecraft did not give NASA scientists any clue about the cluster of bright spots on the dwarf planet.

The planet is the largest celestial body in the asteroid belt between orbits of Mars and Jupiter. Bright spots on the planet were spotted this year when Dawn approached it after observing the giant asteroid Vesta for 11 months. Even though the spacecraft neared Ceres to hover at 4,500 miles in orbit, scientists are not sure what is the underneath reflecting material.

"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 the mission's principal investigator recently said.

The brightest of the spots is said to be in a 50 mile-wide crater. NASA has asked curious minds to guess what is causing the reflection. Volcano, geyser, rock, ice, salt deposit and others are options to choose from.

Dawn will remain in orbit at 2,700 miles over the planet until June 30 and will then ease into closer orbits to study the planet. Dawn was launched in 2007 to study two of the three known protoplanets including Ceres and Vesta, which have remained unchanged since their formation. It is the first spacecraft to use ion propulsion which helps it enter and exit orbits of multiple objects.