Dwarf planets

Dwarf Planets

Dwarf planets are celestial bodies that orbit the Sun and have certain characteristics that distinguish them from the eight major planets in our solar system. The concept of dwarf planets was introduced by the International Astronomical Union (IAU) in 2006, leading to a reclassification of certain celestial bodies.

Definition

According to the IAU, a dwarf planet is a celestial body that:

1. Orbits the Sun.
2. Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly round shape.
3. Has not cleared the neighborhood around its orbit.
4. Is not a satellite.

This definition distinguishes dwarf planets from the eight "classical" planets, which have cleared their orbits of other debris.

Known Dwarf Planets

As of now, there are five officially recognized dwarf planets in our solar system:

• Pluto: Once considered the ninth planet, Pluto was reclassified as a dwarf planet in 2006. It is located in the Kuiper Belt and has five known moons, with Charon being the largest.

• Eris: Discovered in 2005, Eris is slightly smaller than Pluto but more massive. It is located in the scattered disc, a distant area of the solar system.

• Haumea: Known for its elongated shape due to its rapid rotation, Haumea is located in the Kuiper Belt and has two known moons.

• Makemake: Also located in the Kuiper Belt, Makemake was discovered in 2005 and is one of the largest known dwarf planets.

• Ceres: The only dwarf planet located in the asteroid belt between Mars and Jupiter, Ceres was the first dwarf planet to be visited by a spacecraft, Dawn, in 2015.

Characteristics

Dwarf planets share several characteristics with both planets and smaller solar system bodies like asteroids and comets:

• Shape: Dwarf planets are nearly round due to their self-gravity, unlike irregularly shaped asteroids.

• Orbit: They orbit the Sun, but unlike planets, they have not cleared their orbital paths of other debris.

• Location: Most known dwarf planets are located in the Kuiper Belt, a region beyond Neptune filled with icy bodies and remnants from the solar system's formation.

Exploration

The exploration of dwarf planets is a relatively new field in astronomy. The New Horizons mission, launched by NASA in 2006, provided the first close-up images of Pluto and its moons in 2015. The Dawn spacecraft studied Ceres, providing valuable data about its surface and composition.

Importance

Studying dwarf planets helps scientists understand the formation and evolution of our solar system. These bodies are considered remnants from the early solar system, offering clues about the processes that led to the formation of planets and other celestial bodies.

See Also

• Kuiper Belt
• Asteroid belt
• Planetary science