It may be the largest object in the asteroid belt that sits beyond Mars, but the dwarf planet Ceres has been surprising scientists ever since it was discovered.
Now, NASA's Dawn probe has sent back its closest ever look at the surface of Ceres.
This picture, one of the first images returned by Dawn in more than a year, show a rough landscape with a relatively smooth surface.
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This picture is one of the first images returned by Dawn in more than a year, as Dawn moves to its lowest-ever and final orbit around Ceres. Dawn captured this view on May 16, 2018 from an altitude of about 270 miles (440 kilometers). The large crater near the horizon is about 22 miles (35 kilometers) in diameter, which is not far from a series of tholi (small mountains) that include Kwanzaa Tholus. The midsize crater in the foreground is located about 75 miles (120 kilometers) from the large crater.
The transfer from Dawn's previous orbit to its final one is not as simple as making a lane change.
Dawn's operations team worked for months to plot the course for this second extended mission of the veteran spacecraft, which is propelled by an ion engine.
Engineers mapped out more than 45,000 possible trajectories before devising a plan that will allow the best science observations.
'This rough landscape suggests these features are on top of ancient terrains,' NASA said.
The Dawn spacecraft has returned many limb images of Ceres in the course of its mission.
'These images offer complementary perspective to the images generally obtained by imaging the surface directly beneath the spacecraft,' NASA said.
'This example shows that Ceres' limb is relatively smooth despite the rough surface, because this large body is rounded by its own gravity.
The images were taken as Dawn is maneuvering to its lowest-ever orbit for a close-up examination of the inner solar system's only dwarf planet.
In early June, Dawn will reach its new, final orbit above Ceres.
Soon after, it will begin collecting images and other science data from an unprecedented vantage point.
This orbit will be less than 30 miles (50 kilometers) above the surface of Ceres - 10 times closer than the spacecraft has ever been.
Dawn will collect gamma ray and neutron spectra, which help scientists understand variations in the chemical makeup of Ceres' uppermost layer.
That very low orbit also will garner some of Dawn's closest images yet.
This animation shows Ceres as seen by NASA's Dawn spacecraft from its high-altitude mapping orbit at 913 miles (1,470 kilometers) above the surface. The colorful map overlaid at right shows variations in Ceres' gravity field measured by Dawn, and gives scientists hints about the dwarf planet's internal structure. Red colors indicate more positive values, corresponding to a stronger gravitational pull than expected, compared to scientists' pre-Dawn model of Ceres' internal structure; blue colors indicate more negative values, corresponding to a weaker gravitational pull
Ceres is 590 miles (950 km) across and was discovered in 1801.
It is the closest dwarf planet to the sun and is located in the asteroid belt between Mars and Jupiter, making it the only dwarf planet in the inner solar system.
Ceres is the smallest of the bodies currently classified as a 'dwarf planet'.
It lies less than three times as far as Earth from the sun - close enough to feel the warmth of the star, allowing ice to melt and reform.
Nasa's Dawn spacecraft made its way to Ceres after leaving the asteroid Vesta in 2012.
There is high interest in the mission because Ceres is seen as being a record of the early solar system.
Dawn was launched in 2007 and has been exploring the two largest bodies in the main asteroid belt, Vesta and Ceres, to uncover new insights into our solar