Mercury – first of eight planets
Mercury is the first of eight planets and the smallest one. It is the closest planet to the Sun. It was named for the wing-footed Roman god. Mercury is visible to the naked eye from Earth. Mercury will either set within two hours of sunset, or rise no earlier than two hours before the Sun.
It is only slightly bigger than Earth’s Moon. Many different gases surround the planet. It has a very thin atmosphere of oxygen, potassium, and sodium vapors.
Planet’s hottest temperature is 400° C during a Mercurian day and its coldest is -173° C during a Mercurian night. This temperature variation is due to the fact that Mercury has essentially no insulating atmosphere.
In 1974 and 1975 the spacecraft Mariner 10 flew close to Mercury. Its surface is covered with a layer of broken rock called “regolith” and is similar to the surface of the Moon.
Mercury’s average distance from the sun is about 58 million kilometers. It travels around the sun at a faster speed than any other planet.
Its landscape includes flat plains and long, steep cliffs.
One year on Mercury lasts 88 Earth days. A day on Mercury lasts about 176 Earth days. So a day is longer than a year.
Next to the planet Pluto, Mercury is one of the least explored planets within our solar system.
The Greek philosopher Plato refers to the distinctive yellow color of Mercury in Book X of his Republic.
The discovery of water ice on Mercury was made in 1991.
This planet has no natural satellites and consequently it is not an easy task to determine the planet’s mass.
Mercury receives 7 times more solar energy than the Earth. However, it has magnetic field many times weaker than the earth’s.
The radius of the planet is 2439 km and its diameter is about 4878 km.
Astronomers put forward a version that Mercury has an iron core. Presumably it is 80% of the mass of the whole celestial body.
The largest crater, the diameter of which is 716 km, was named in honor of Rembrandt.
The height of some mountains on Mercury can reach 4 km.
There is a hypothesis that Mercury was previously a satellite of Venus.
Mercury has a faintly visible tail, like a comet, which is two and a half million kilometers in length.