Mercury: The Swift Planet

Overview

Mercury is the smallest planet in our solar system - with a radius of only 2,439.7 km. It is also the closest planet to the sun. Mercury is also known as the "Swift Planet" because of its short orbit time of 88 days around the Sun. From the surface, the sun would appear 3 times bigger and 7 times brighter on mercury than on earth. But despite its distance to the sun, it is not the hottest planet - that title goes to its neighbour, Venus.

Description

Mercury is formed around 4.5 billion years ago. With a radius of 1,516 miles, Mercury is a little more than 1/3 of the width of Earth. For comparision, if Earth were the size of a coin, Mercury would be about as big as a blueberry. Mercury is about 0.4 astronomical units (36 million miles)* away from the Sun. From this distance, it takes sunlight 3.2 minutes to travel from the Sun to Mercury.

Orbit and Rotation:
Mercury completes an orbit around the Sun every 88 days, travelling through space at nearly 29 miles (47 kilometers) per second. Mercury spins slowly on its axis and completes one rotation every 59 Earth days. Mercury's axis of rotation is tilted just about 2 degrees. And so it doesn't experience seasons as many other planets do.

Structure:
Mercury is the second densest planet with a large metallic core with a radius of about 1,289 miles (2,074 kilometers) Mercury's outer shell** is only about 250 miles (400 kilometers) thick.

Surface:
Mercury's surface resembles that of Earth's moon - scarred by many impact craters from collisions with meteoroids and comets. To the human eye, Mercury's surface would appear greyish-brown.

Temperatures:
During the day, temperatures on the surface can reach 430 degrees Celsius (800 degrees Fahrenheit) and since there isn't any atmosphere to retain the heat, the temperature can drop to -180 degrees Celsius (-290 degrees Fahrenheit).

Atmosphere:
Mercury doesn't have an atmosphere, but possesses a thin exosphere that is composed mostly of oxygen, sodium, hydrogen, helium and potassium.

Magetosphere:
Mercury's magnetic field is offset relative to the planet's equator and the strength of the magnetic field is only 1% that of Earth's.

Fun Facts!

• Mercury's size is the same as 0.38 Earths
• Mercury's mass is 3,377 kilograms or the same as 0.055 Earths
• Not only is Mercury the smallest planet, it is also shrinking
• Mercury orbits the Sun faster than any other planets
• Mercury doesn't have any moons
• Mercury was named after the Roman god of commerce, Mercurius (Mercury)

Simulations

Footnotes:

*One astronomical unit (abbreviated as AU) is the distance from the Sun to Earth.

**The outer shell is called the mantle and crust.