Like the other planets in our solar system, Mercury has also formed 4.5 billion years ago. Mercury was named after a Roman god and is also known as Hermes in Greek mythology. Mercury was the god of translators and interpreters, and he was the most clever of the Olympian gods.
Mercury is the smallest planet in the solar system. Its diameter is currently measured at just over 3000 miles, about the size of the United States of America. Mercury is one of the 4 terrestrial planets and has 3 main layers. Because of its crust, mantle, and core, its crust has no tectonic plate. The iron core is massive, making up 85% of its radius. Because of the core size, it has a surprising influence on mercury's size by causing it to shrink. The hot iron core has slowly cooled down. In doing so, it pulls the mercury surface inward and has caused the planet to shrink.
Mercury is also the closest planet to the sun, orbiting our solar system star at a distance of roughly 36 million miles. Because it is so close to the sun, this affects the mercury atmosphere. It only has a thin exosphere, which is the outermost layer of a planet's atmosphere. This exosphere is made of oxygen, sodium, hydrogen, helium, and potassium, all whipped up from the planet's surface by the solar wind. The lack of atmosphere and proximity to the sun makes the planet's surface temperature rise to about 800 degrees Fahrenheit during the daytime and fall to about-290 degrees below zero at night.
Due to the proximity of the planets to the sun, the sun's gravity pulls harder on mercury than on any other planet. Like other planets, mercury travels in an elliptical orbit, slowing down when it's far away from the sun and accelerating as it gets closer. With an average speed of 100,000 miles per hour, mercury completes its orbits in 88 days. Mercury is difficult to observe from Earth because it is too close to the sun and has only been visited by two spacecraft mariner and messager missions gave us what we know about mercury today, but future ventures are at work and, hopefully, they will reveal more of mercury's secrets.
