Tutorial Topics
Satellites - Move Around The Planet Dwarf Planets - Eris, Haumea and Makemake
Dwarf Planets - Ceres and Pluto - Physical Geography
10175    Dibyendu Banerjee & Sudipta Banerjee    24/02/2018

Dwarf Planets

According to the International Astronomical Union, a ‘Dwarf Planet ‘is a celestial body orbiting a star like the planets, but is neither a planet nor a natural satellite, which is massive enough to become spherical in shape under its own gravity, but  has not cleared the neighborhood around its orbit. Unlike the planets, the Dwarf Planets share their orbits around the sun with other celestial objects like asteroids and comets.

The first five recognized Dwarf Planets recognized by the International Astronomical Union are : Ceres, Pluto, Eris, Haumea, and Makemake. Among them, only  Ceres, is located in the asteroid belt, while the others  are in the outer solar system. However, according to NASA, scientists think that there may be more than a hundred Dwarf Planets awaiting discovery.

1. Ceres

Ceres - Dwarf Planets

 Ceres is the largest object in the asteroid belt between Mars and Jupiter. For many years it was classified as an Asteroid. But, it is so much bigger and so different from its rocky neighbors that scientists categorized it as a dwarf planet in 2006. Though Ceres makes up approximately a fourth of the mass of the asteroid belt, it is still 14 times less massive than Pluto. It is so small that, it is often regarded as one of the largest Asteroid in the Solar System. However, unlike Asteroids, Ceres has a nearly round body. With a radius of 296 miles (476 kilometers), Ceres has 1/13 the radius of Earth.

Ceres takes 1,682 Earth days to make one trip around the sun. Since its axis is tilted just 4 degrees, it spins nearly perfectly upright and doesn't experience seasons like other more tilted planets do, and it completes one rotation every 9 hours, making the length of its day one of the shortest in the solar system. Possibly, Ceres has a solid core and a mantle made of water ice. It is covered with countless small, young craters, but none are larger than 175 miles (280 kilometers) in diameter. Ceres has a very thin atmosphere, and in 2014, Herschel Space Observatory, spotted evidence of water vapour in Ceres. 

2. Pluto

Pluto - Dwarf Planets

Discovered in 1930, icy Pluto was long considered as the ninth planet of our solar system. But after the discovery of several other rocky bodies similar in size or larger than Pluto deeper in the distant Kuiper Belt, the IAU decided to relegate it to the status of a Dwarf. Probably Pluto is a small body, with a diameter less than that of Mars. It has a rocky core surrounded by a mantle of water ice. It has an extraordinary orbit, which is so elliptical that, when Pluto is close to the sun, its surface ices sublimate, changing directly from solid to a gas and rise and temporarily form a thin atmosphere. Pluto has a very large moon, which is almost half its size named Charon. Charon was discovered in 1978. Unlike the Moon, it never rises nor sets, but hovers over the same spot on Pluto's surface, and the same side of Charon always faces Pluto.

Satellites - Move Around The Planet Dwarf Planets - Eris, Haumea and Makemake
Author Details
Dibyendu Banerjee & Sudipta Banerjee
Article by Dibyendu Banerjee, an Ex-student of Scottish Church College, Kolkata. Authored several novels in Bengali and translated into Bengali novels/short stories of eminent writers of the world. Regularly contributes articles to different web sites on different subjects. Edited by Sudipta Banerjee, educated at Loreto House, Kolkata. Completed her B.A [Hons] in Geography and M.A from Presidency College, Kolkata, B.Ed from the Institution of Education for Women, Hasting House, Kolkata. Taught for 38 years, as Middle School Mistress at Victoria Boys School, Kuseong and as Asstt Teacher in Geography at Multipurpose Govt Girls School, Kolkata.
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