For many fans of the celestial body formerly known as the planet Pluto, the decision by the International Union of Astronomers to reclassify it as a dwarf planet in 2006 came as a shock. But long before Pluto was downgraded — or even discovered — another spherical chunk of rock and ice in our Solar System was given, and subsequently stripped of, planetary status.
Ceres, the smallest known dwarf planet in our Solar System, was considered a planet for more than 50 years before being reclassified as an asteroid during the mid-19th Century. More than 150 years later, Ceres got its due, and was upgraded to dwarf planet status. Here are some more interesting facts about Ceres:
– Ceres was discovered on January 1, 1801, by Italian astronomer and clergyman Giuseppe Piazzi. About a half century later, it was added to a newly-discovered class of objects called asteroids, before finally being classified as a dwarf planet in 2006.
– Ceres is located in an area of space known as the asteroid belt, which is located between the planets Mars and Jupiter. This area is populated by hundreds of thousands of irregularly shaped bodies that orbit the Sun. Ceres is the largest object in the belt, comprising about one third of the total mass of all objects found there.
– The surface of Ceres is believed to be a primarily a layer of ice over a rocky core. There may also be liquid ocean trapped beneath the icy surface.
– Ceres is 580 miles in diameter, and only about 1.5% as massive as our own Moon.
– It takes Ceres about 4.6 Earth years to orbit the sun, and 9 hours and 4 minutes to spin once on its axis.
– Ceres has no known moons. This is not because of its diminutive size, however. Astronomers have discovered asteroids smaller than Ceres that have tiny natural satellites.
– Ceres is named after the Roman goddess of the harvest, whose Greek name is Demeter.
– The maximum temperature on Ceres is about -36° F, and the average temperature is about -159° F, a much smaller range than its closet neighbor, Mars.
– Because of its small size, Ceres has only a very thin atmosphere. Ice on its surface sublimates directly into water vapor and escapes into space.
– Ceres is too dim to view with the naked eye, though it can be seen via telescope. Consult your favorite star chart for help locating it.
Image credit: William K. Hartmann. Courtesy of UCLA.