Last March, NASA's Dawn spacecraft made history when it became the first mission to ever orbit a dwarf planet.
Before Dawn, the best images we had of the dwarf planet Ceres were taken by the Hubble Space Telescope in the early 2000s from a distance of 257 million miles away. And about the only thing these fuzzy photos were good for was to spark one of the most outstanding questions in astronomy today: What is that bright, white dot?
(NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), and L. McFadden (University of Maryland, College Park))
As Dawn approached Ceres earlier this year, it snapped pictures that slowly but surely resolved the white dot so scientists at least had some idea of its size. This photo was taken on January 25 when Dawn was 147,000 miles away:
Then, one month later, on February 25, Dawn made its greatest contribution yet: It showed us that Ceres doesn't have just one spot: It had at least two! Dawn took this photo from 29,000 miles away:
Then, in March, Dawn began orbiting Ceres, and ever since it has been descending ever closer to the surface (but it will not land). That means every new image Dawn transmits to Earth is even more detailed and better than the last. And as it gets closer, Dawn is proving that there's not just one or two of these mysterious dots, but there are many!
Shown below are some of Dawn's first close-up shots of Ceres taken last March, snapped from 8,700 miles above the dwarf planet's surface:
Your browser does not support the video tag. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
But that's nothing compared to the image that NASA just released today, June 10.
Check out this incredible shot that Dawn took from 2,700 miles above Ceres' surface — 6,000 miles closer than the images shown above. This is the closest photo we have yet of the mysterious white spots on Ceres:
But even with this level of detail, scientists still can't say for certain what the shiny speckles might be.
"The bright spots in this configuration make Ceres unique from anything we've seen before in the solar system. The science team is working to understand their source," Chris Russell, principal investigator for the Dawn mission, said in a NASA statement about the latest Dawn images. "Reflection from ice is the leading candidate in my mind, but the team continues to consider alternate possibilities, such as salt."
Other possibilities include some bizarre type of volcanic or geyser activity. Whether the answer is any one of these, however, is anyone's guess at this point. And there's always the chance it's something scientists haven't even considered.
June 6 marked the start of Dawn's first intense survey of Ceres. Over the course of this month, the spacecraft will use some of its instruments to generate a global map of this tiny, crater-ridden world before it spirals even closer — 900 miles above the surface — in August. So stay tuned for even better photos coming soon.
Also check out this amazing computer-animated overview of Ceres generated from the thousands of image that Dawn has collected so far:
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