Found in 1930, Pluto has long been considered a ninth planet in our solar system. However, on August 24, 2006, after the discovery of a deeper planet in the Kuiper belt, Pluto was no longer considered a planet and was moved to a dwarf planet by the International Astronomical Union (IAU).
According to IAU in 2006, the planet wipedi was defined as a celestial body that surrounds the sun and has enough mass to form a circle, but does not have enough gravity to clean the area around its orbit. Pluto is classified as a dwarf planet because it is located in the trans-neptune region, where many other objects share their orbits.
With a diameter of about 2,200 kilometers, Pluto size is about half of the width of the United States. This dwarf planet is located very far from the sun, which is around 6.6 billion kilometers, and has a thin atmosphere dominated by nitrogen, methane, and carbon monoxide. The surface temperature is very cold, on average -232 ° C (-387 ° F), it is not possible to support life.
Pluto is surrounded by five months, with Charon as the largest. The size of Charon, which is almost half of Pluto, makes their system often dubbed as a “double planet” system.
The IAU members decided that the requirements of a planet in the solar system are as follows:
- Orbit the sun
- The mass of the object must be large enough so that the gravity is almost round.
- Has cleaned the orbit: the planet must be the dominant gravitational force in its orbit and there are no other objects with the exact same size that orbits in the same region.
This is the main reason Pluto is no longer categorized as a planet, because his orbit in the Kuiper belt is still filled with many other small objects.
Pluto failed to meet the conditions
Pluto has a small measure and a very sloping elliptical orbit, making it a debate for years. With a diameter of only 2.300 kilometers, the pluto is much smaller than the moon.
Pluto also crossed Neptune’s orbit on his way around the sun which lasted for 247 years of the earth.
All of these reasons question their status as a planet.
So, now we have eight planets in our solar system:
- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Source: cnes.fr, NASA, eso.org
