Finally — A Super-Close Look At Ceres’ Brightest Spot

This mosaic of Cerealia Facula, one of Ceres’ most prominent “bright spots” in Occator Crater is based on images obtained by NASA’s Dawn spacecraft in its second extended mission, from an altitude as low as about 21 miles (34 km). A few small sections were photographed at lower resolution. Click for a big picture view. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

What a feast for the eye! Some of us have been waiting more than three years for this image. It’s the closest view yet of the brightest spot on Ceres, an asteroid and dwarf planet orbiting within the main asteroid belt. Once known as “Spot 5”, the scintillating splotch has since been named Cerealia Facula (Latin for ‘Ceres bright spot’). Early in the Dawn spacecraft’s mission to dwarf planet, it immediately caught everyone’s eye and sparked a lot of speculation about its origin.

NASA’s Dawn spacecraft took this and other photos of small, highly reflective patches inside Occator Crater from an altitude of just 21 miles (34 km) earlier this month. The wealth of detail is incredible — the entire dome is crisscrossed by fractures and pocked with depressions.

Remember this view? It was taken by Dawn on May 4, 2015, more than 3 years ago, from an altitude of 8,400 miles. The photo provided a tantalizing look at Cerealia Facula (round spot on left side) and Vinalia Faculae (spot cluster on the right side) inside the 57-mile-wide Occator Crater. At the time, no one really knew what they were. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

The bulbous dome and surrounding terrain span about 6 miles (10 km); their brilliant, white highlights are composed primarily of sodium carbonate and ammonium chloride, both salts. They’re what remained after briny waters percolated up from below to the surface. The water quickly vaporized on the airless dwarf planet, depositing its load of salts as a bright, white coating. Astronomers believe Cerealia Facula formed through recurring eruptions, with material sprayed across the local landscape, so we’re probably looking at layers of sodium bicarbonate, thicker in some places than others. Geologic activity involving ice and water instead of magma is known as cryovolcanism.

This close-up image of the Vinalia Faculae, another bright spot in Occator Crater, was obtained by NASA’s Dawn spacecraft in its second extended mission from an altitude as low as 21 miles (34 km). NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Based on crater counts, Occator Crater is estimated to be 34 million years old, but the bright spots inside are much younger, only about 4 million years old. That’s almost like yesterday in geologic time. Dawn also mapped Ceres’ gravity field and discovered that it has a rocky core and icy mantle. It’s likely that crater-forming asteroid impacts tapped into that mantle, creating the fractures and low spots that later led to the release of trapped liquids from beneath the surface.

Ceres may still be active to this day. Check out more recent photos taken from Dawn’s new, low orbit.

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