TRIESTE, Italy, March 16 (UPI) -- Ceres' bright spots change on a daily basis. The new findings suggest the bright spots are composed of volatile materials.
New data collected by the European Southern Observatory's La Silla Observatory in Chile show Ceres' bright spots get brighter during the day and exhibit other measurable variations. Researchers believe some of the bright spots' material sublimates in the midday sun.
Ceres is a dwarf planet and the largest object in the asteroid belt running between the orbits of Mars and Jupiter.
Since imaging it in detail for the first time last year, astronomers and citizen scientists have been captivated by the dwarf planet's bright spots, various points that reflect much more sunlight than the surrounding terrain. Researchers believe the spots are composed of salts or ice.
The latest discovery was made possible not by a space-based probe, like NASA's Dawn craft, but by ground telescopes.
"As soon as the Dawn spacecraft revealed the mysterious bright spots on the surface of Ceres, I immediately thought of the possible measurable effects from Earth," astronomer Paolo Molaro, a researcher at the Trieste Astronomical Observatory in Italy, said in a news release. "As Ceres rotates the spots approach the Earth and then recede again, which affects the spectrum of the reflected sunlight arriving at Earth."
But calculations confirmed the act of rotating away from or toward the Earth is not enough to explain the changes detailed by the observatory's HARPS spectrograph. Thus, astronomers concluded the spots themselves are changing over the course of each day on Ceres.
"The result was a surprise," added Antonino Lanza, an astronomer at the Catania Astrophysical Observatory. "We did find the expected changes to the spectrum from the rotation of Ceres, but with considerable other variations from night to night."
The latest findings were published this week in the journal Monthly Notices of the Royal Astronomical Society.