Group Q Dwarf Planets

What is a Dwarf Planet
Dwarf planets share many of the same characteristics as planets though there is one significant difference. The International Astronomical Union’s definition of a dwarf planet is:
A “dwarf planet” is a celestial body that
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
(c) has not cleared the neighbourhood around its orbit, and
(d) is not a satellite.
The key difference is that a planet has cleared other objects in the area of its orbit while a dwarf planet has not.

Sizes of dwarf planets
Ceres 950 km 413,700,000 km (2.77 AU) 4.6 years
Pluto 2,372 km 5,874,000,000 km (39.26 AU) 246.0 years
Haumea 1,960 km - 1,518 km × 996 km 6,452,000,000 km (43.13 AU) 283.3 years
Makemake 1,434 km × 1,422 km 6,850,000,000 km (45.79 AU) 309.9 years
Eris 2,326 km 10,120,000,000 km (68.01 AU) 560.9 years

Facts about Dwarf Planets
Pluto Facts**
Diameter: 2,372 km
Mass: 1.31 × 10^22 kg (0.17 Moons)
Orbit Distance: 5,874,000,000 km (39.26 AU)
Orbit Period: 246.0 years
Surface Temperature: -229°C
Moons: 5 (Charon)
Discovery Date: February 18th 1930
Discovered By: Clyde W. Tombaugh
pluto-size.png
Pluto was reclassified from a planet to a dwarf planet in 2006.
This is when the IAU formalised the definition of a planet as “A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.”Ceres Facts
Diameter: 950 km
Mass: 8.96 × 10^20 kg (0.01 Moons)
Orbit Distance: 413,700,000 km (2.8 AU)
Orbit Period: 1,680 days (4.6 years)
Surface Temperature: -105°C
Moons: None
Discovery Date: 1st January 1801
Discovered By: Giuseppe Piazzi
ceres-size.png
Ceres accounts for one third of the mass in the asteroid belt.
Despite this it is still the smallest and least massive of the dwarf planets. 1-40-dwarfplanet.jpg
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