The Ceres is the only dwarf planet which orbits inside the asteroid belt, inner solar system. The Ceres is largest asteroid and dwarf planet of inner solar system. First the Ceres was discovered in 1801 by Giuseppe Piazzi. The Ceres is named upon the roman goddess of agricultural. It is too dim to see by naked eyes. From 1802 to 2006 it was known as largest asteroid. The Ceres is the only which has the largest water reservoir in inner solar system other than the Earth.
Properties of Ceres
- The Ceres was discovered by Giuseppe Piazzi in 1st January 1801.
- It was named upon Roman goddess of agricultural.
- It is the first dwarf planet which is visited by space craft.
- It is only dwarf planet which orbits in the inner solar system.
- Mean diameter is Ceres is 939 km and mass is 9.38 X 1020 kg.
- It has solid core and water ice mantle.
- The orbital period is about 4.6 Earth’s years.
- Axial tilt is about 4o and one day is about 9 hours.
- The orbit is inclined by 10.06o with eccentricity is about 0.08.
- Its Aphelion (Farthest distance from Sun) is 445,749,000 km and Perihelion (Closest distance from Sun) is 382,774,000 km.
- Average orbital speed of Ceres is 17.905 km/s.
- It has no moon, ring and also magnetosphere.
The Ceres was formed before 4.5 billion years ago when rest of the solar bodies were formed from solar nebulae. The Ceres is called embryonic planet means it starts to form the planet but could not be planet due to gravity of Jupiter. Before 4 billion years ago, it may be settled in asteroid belt while other bodies were pulled out to outer solar system.
Internal structure & Surface
The internal structure of Ceres is just like to terrestrial planets like Mercury, Venus, Earth and Mars but it is less dense. The Ceres has solid core and mantle of water ice outside the core. The Ceres is made of about 40% to 50% of water by volume and 73% rock by volume. The craters on surface indicate that the outer surface is about 1000 times stronger than water ice.
According to three layer model theory, The Ceres is composed of inner muddy hydrated rock like clay, about 100 km thick intermediate layer of brine and rock and outer crust of ice, salt and hydrated minerals with 40 km thick. According to two layer model theory, Ceres has core of chondrules and mantle of ice and mud.
The surface is mixture of water ice and various hydrated materials like carbonates and clays. The water ice layer on surface varies from polar to equatorial region and almost ice free at equatorial region. The surface of Ceres is warm enough to evaporate ice from creaters and materials left after that shows dark surface. Mainly graphite, sulfer and sulfer dioxide are present on the surface of Ceres. The surface of the Ceres has number of small craters which are not more than 280 km in size which indicate that at the time of evolution it was hit by many asteroids. Among them many craters have central pit while some have central peaks. The Ceres has mountain named “Ahuna Mons” which was done by cryovolcanic process having height about 4000 meter. It is the largest mountain on the Ceres. Bright streaks run from top to botom on slops which are made of salts. Many bright spot are also visible on surface of Ceres, brightest spot is located in middle of 80km crater which is known as “Occator”. The surface is rich in carbon and about 20% carbon by mass in its surface.
Orbit and Rotation
The orbital path of Ceres lies between the orbit of Mars and Jupiter and nearer to the Mars and within the asteroid belt. It takes 4.6 years to complete one revolution around the Sun. The orbit is eccentric by 0.08 and incline by 10.6o to elliptical plane. Average orbital speed of Ceres is 17.905 km/s. The Maximum distance from the sun (Aphelion) is 445,749,000 km while minimum distance from the sun (Perihelion) is 382,774,000 km.
The axial tilt of Ceres is about 4o. It spins on its own axis in 9 hours means one day is 9 hours long.
The Ceres has water vapour atmosphere which forms by out gassing from water ice. The presence of atmosphere is linked with solar activity. When the surface is direct toward the sun light, ice from deep layer of craters is sublimed and exposed to vacuum and create exosphere which lasts for two weeks. Surface sublimation is lower when the Ceres is farthest from the Sun. The surface temperature of Ceres is -163o C to -118oC.
The Ceres has no any moon or rings system
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Authored by BK Suthar.
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