In a Category All Their Own: Dwarf Planets

Once the object is large enough to have a stronger gravitational field, it is no longer a dwarf. In general, the best known dwarf mass is less than Mercury's mass. The lower limit depends on the requirements for achieving the hydrostatic equilibrium shape. Hydrostatic pressure balance is the current distinction criterion between dwarf planets and other Go 3 celestial bodies. The hydrostatic equilibrium shape means that the object is rounded to a spherical shape or an elliptical shape symmetrically.

On August 24, 2006, the International Astronomical Union (IAU) decided the meaning of the "planet" in the solar system. This definition excludes Pluto from the planet and adds it as a member of the new category "dwarf" along with Ellis and Ceres. After the decision of the IAU, Kenyon D. Wilson created the Trombone Quintet called "The Song of the Earth". The title comes from Arthur C. Clark's novel of the same name. The work consisted of five movements, each named after one of five known dwarf planets Eris, Pluto, Haumea, Makemake, Ceres. Unlike Matthews' work, this work is not intended to be integrated into Holst Suite's performance.

Ceres (2.77 AU) is the largest asteroid, primitive planet and dwarf. Its diameter is slightly less than 1000 kilometers, and its mass is sufficient to make its own gravity to pull it to a spherical shape. Ceres was considered a planet discovered in 1801 and was reclassified as an asteroid in the 1950s. In 2006, when the planetary definition was created, it was classified as a dwarf. Asteroids in the asteroid belt are divided into asteroid groups and families according to their trajectory characteristics. An asteroid satellite is an asteroid orbiting a larger asteroid. They are not as obvious as planetary satellites, and sometimes as big as their partners. The asteroid belt also contains the main comets. This may be a source of water from the earth.

Pluto is more than twice the diameter of the Dwarf planet Ceres and is the largest object in the asteroid belt. The diameter of Pluto is 2376.6 kilometers, and the diameter of Ellis is about 2,326 kilometers. Determining the size of Pluto is complicated by its atmosphere and the smog of hydrocarbons. March 2014, Lellouch, de Bergh etc. The result of Pluto's atmospheric methane mixing ratio was announced. There, the Plutonian diameter was greater than 2360 km, and the "best guess" was 2368 km. On July 13, 2015, images from NASA's New Vision Mission Remote Reconnaissance Imager (LORRI) and other equipment were changed to Pluto's diameter of 2,370 km (1,470 miles), then changed to 2,372 km (1,474 miles) I judged. After 24 July 2374 ± 8 km