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Exploring dwarf planet Ceres


Header image: William K. Hartmann Courtesy of UCLA

If you got into a rocketship and tried to take a trip out to the end of our solar system, you would have to pass through the main asteroid belt that orbits the sun between Mars and Jupiter. Not only would you find asteroids of all shapes and sizes here, but you would also see the largest object between Mars and Jupiter - a dwarf planet named Ceres (say “see-rees”). Until now, no one has explored Ceres, but that’s all about to change.

The solar system - dwarf planet Ceres orbits in the main asteroid belt between Mars and Jupiter

The solar system - dwarf planet Ceres orbits in the main asteroid belt between Mars and Jupiter (Photo by Image Editor licensed CC BY 2.0)

For over seven years, NASA’s Dawn spacecraft has been travelling 4.8 billion km (3 billion miles) just so that it can explore Ceres up close for the first time. Scientists are eager to find out just what might be under the dusty outer crust, as there are signs that there may be large amounts of water and ice beneath its surface. On March 6, 2015 they will finally get a chance to do this when the Dawn spacecraft finally reaches Ceres.

NASA's Dawn spacecraft on its way to Ceres

NASA’s Dawn spacecraft on its way to Ceres - artist rendering (Image courtesy NASA/JPL-Caltech)

So what’s a dwarf planet?

Discovered in 1801 by a Sicilian astronomer, Ceres was originally called a planet, but was later changed to a dwarf planet along with Pluto in 2006.

So what’s the difference between a regular planet and a dwarf planet? They both orbit around the sun, have a nearly round shape and are not satellites (that’s what our moon is). But unlike a planet, a dwarf planet shares its orbit with many other celestial bodies. Ceres is a dwarf planet because it shares its orbit with millions of asteroids in the main asteroid belt.

Earth, the moon and Ceres size comparison

Earth, the moon and dwarf planet Ceres - see how small it is compared to our planet. (Photo by Brian Altmeyer licensed CC BY 2.0)

How Ceres got its name

The dwarf planet Ceres was named after the Roman goddess of agriculture and grains. This is also where we get our word for “cereal.”

Life on Ceres

Since Ceres takes much longer to rotate around the Sun than Earth does, one year on Ceres is the same as 4.6 Earth years - that’s over 1500 days. That’s a lot of school days! Luckily, days are different on dwarf planets - one day on Ceres only lasts 9 hours instead of Earth’s 24 hour day..