Mercury vs. Pluto

Attribute	Mercury	Pluto
Diameter	4,880 km	2,377 km
Distance from Sun	57.9 million km	5.9 billion km
Orbital Period	88 days	248 years
Moons	0	5
Atmosphere	Thin	Thin

Physical Characteristics

Mercury and Pluto are two very different planets in our solar system. Mercury is the smallest planet and closest to the sun, while Pluto is a dwarf planet located in the outer reaches of the solar system. Mercury is a rocky planet with a thin atmosphere, while Pluto is composed mostly of ice and rock. Mercury has a diameter of about 4,880 kilometers, while Pluto is slightly larger with a diameter of about 2,377 kilometers.

Orbit and Rotation

Mercury orbits the sun at a distance of about 57.9 million kilometers, completing a full orbit in just 88 Earth days. Its rotation is also unique, as it rotates on its axis three times for every two orbits around the sun. In contrast, Pluto orbits the sun at an average distance of about 5.9 billion kilometers, taking about 248 Earth years to complete one orbit. Pluto's rotation is also unusual, as it rotates on its side with an axial tilt of about 120 degrees.

Surface Features

Mercury's surface is heavily cratered, with large plains and cliffs caused by tectonic activity. It also has a large iron core, which gives it a strong magnetic field. In comparison, Pluto's surface is covered in icy mountains, plains, and valleys. It has a thin atmosphere composed of nitrogen, methane, and carbon monoxide. Pluto's surface is constantly changing due to its elliptical orbit and the presence of volatile ices.

Atmosphere and Temperature

Mercury has a very thin atmosphere composed mainly of oxygen, sodium, hydrogen, and helium. Its surface temperature can vary greatly, ranging from about -173 degrees Celsius at night to 427 degrees Celsius during the day. In contrast, Pluto has a thin atmosphere that freezes and falls to the surface as snow as it moves farther from the sun. Pluto's surface temperature is much colder, averaging around -229 degrees Celsius.

Moons

Mercury does not have any moons, while Pluto has five known moons: Charon, Styx, Nix, Kerberos, and Hydra. Charon is the largest moon and is so massive compared to Pluto that the two bodies orbit each other around a common center of mass. The other moons are much smaller and have irregular shapes. These moons play a role in shaping Pluto's orbit and surface features.

Discovery and Classification

Mercury has been known since ancient times and was observed by the Babylonians, Greeks, and Romans. It was named after the Roman messenger god because of its fast orbit around the sun. Pluto, on the other hand, was discovered in 1930 by American astronomer Clyde Tombaugh. It was classified as the ninth planet in our solar system until 2006 when it was reclassified as a dwarf planet due to its small size and eccentric orbit.

Conclusion

In conclusion, Mercury and Pluto are two fascinating worlds with unique characteristics. Mercury is a small, rocky planet close to the sun, while Pluto is a dwarf planet with a composition of ice and rock in the outer solar system. Their differences in size, orbit, surface features, atmosphere, and moons make them intriguing objects of study for astronomers and planetary scientists alike.