Ceres used to be labeled a planet when it was first discovered in 1801. It circles our sun between Mars and Jupiter. So yes, It is part of the asteroid belt.

Layers of asteroid Ceres

Ceres is about the size of Texas. Though it comprises 25% of the total mass of the asteroid belt, it still is smaller than even the tiny Pluto, 14 times smaller.

Though it is not considered a planet, it shares some of the characteristics of rocky planets like Mars. Ceres is believed to have a differentiated interior. Which means, it's more dense at the core than at the surface.

Ceres is believed to possibly have more water than the amount of fresh water on earth. It is believed so because Ceres is less dense than the surface of earth, and surface bears evidence of water-containing minerals. No direct evidence yet exists that Ceres contains water indeed.

Ceres was discovered by Sicilian astronomer Father Giuseppe Piazzi. He spotted the object as he was looking for a suspect planet between Mars and Jupiter. When he found it, he called it a planet. Later, it was classified as an asteroid. In 2006, it was promoted to the status of a dwarf planet, in line with Pluto and Eris. in recognition of its planet-like characteristics.

The Facts

Discovered By
Giuseppe Piazzi
Date of Discovery
1 Jan. 1801
Orbit Size Around Sun (semi-major axis)
Metric: 413,690,250 km
English: 257,055,204 miles
Scientific Notation: 4.1369025 x 108 km (2.7653485 x 100 A.U.)
By Comparison: Earth is 1 A.U. from the Sun
Perihelion (closest)
Metric: 380,951,528 km
English: 236,712,305 miles
Scientific Notation: 3.80952 x 108 km (2.547 x 100 A.U.)
Aphelion (farthest)
Metric: 446,428,973 km
English: 277,398,103 miles
Scientific Notation: 4.46429 x 108 km (2.984 x 100 A.U.)
Orbit Circumference
Metric: 2,595,217,959 km
English: 1,612,593,677 miles
Scientific Notation: 2.595 x 109 km
By Comparison: 2.761
Average Orbit Velocity
Metric: 64,360 km/h
English: 39,991 mph
Scientific Notation: 1.7878 x 104 m/s
By Comparison: 0.600
Orbit Eccentricity
0.079138251
Orbit Inclination
10.59
Mean Radius
Metric: 476.2 km
English: 295.9 miles
Scientific Notation: 4.7620 x 102 km
By Comparison: 487.3 x 454.7 km oblate spheroid
Equatorial Circumference
Metric: 2,992.1 km
English: 1,859.2 miles
Scientific Notation: 2.99205 x 103 km
By Comparison: 0.0747
Volume
Metric: 452,331,448 km3
English: 108,520,085 mi3
Scientific Notation: 4.52331 x 108 km3
Mass
Metric: 947,000,000,000,000,000,000 kg
Scientific Notation: 9.47 x 1020 kg
Density
Metric: 2.09 g/cm3
Surface Area
Metric: 2,849,631 km2
English: 1,100,249 square miles
Scientific Notation: 2.8496 x 106 km2
Surface Gravity
Metric: 0.28 m/s2
Escape Velocity
Metric: 1,855 km/h
Sidereal Rotation Period (Length of Day)
0.378 Earth days
9.07417 hours
By Comparison: 0.38

Sources:

"Ceres", http://solarsystem.nasa.gov/planets/profile.cfm?Object=Dwa_Ceres



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