The Planet Mercury

The Planet Mercury
The picture of planet Mercury taken by NASA’s Messenger. (Credit: NASA)

The planet Mercury is the closest planet to the sun orbiting at a distance of 58,000,000 km and is the smallest planet in our solar system, having diameter of 4,880 km. Planet Mercury takes 88 days to complete the revolution around the sun and 58 days to spin on its axis means day length of Mercury is equal to 58 days of Earth. The velocity of Mercury during revolution around the Sun is fastest in all the planets. The eccentricity of orbit of the planet
Mercury is largest in all the planets of our solar system. The perihelion of Mercury also advances by small amount after each rotation. The axis of the planet Mercury is tilted by smallest amount (1/30 degree) as compared to all other planets. The planet Mercury has no moon.

The Surface of Mercury

The planet Mercury is very hot and looks like a bare ball of rocks with no atmosphere and water, this is due to small size of Mercury and the solar wind which bombards the surface of Mercury. The surface of mercury planet is marked with lot of craters. The meteors can easily hit the surface and create large crater because atmosphere is not there to slow them down and burn them.


Any crater with diameter more than 250 km is referred to as basin. The Caloris basin is the largest impact crater on Mercury with diameter of about 1550 km and was discovered by Mariner 10 in 1974. Amazingly, radar observations of the planet Mercury’s North Pole (a region not mapped by Mariner 10) show evidence of water ice in the protected shadows of some craters.

The Surface Temperature of the planet Mercury

The surface temperature of Mercury is highly variable. In the equatorial region, the temperature in daytime is around 427 degree Celsius and in night, it is around -170 degree Celsius. The Polar Regions are very colder and have temperature always less than -93 degree Celsius, that’s why they are able to hold water in the form of ice.

The Observation of the planet Mercury

The Planet Mercury can be seen as a twinkling star just after sunset and just before dawn because it is very closest to the Sun. Because of this it is also called Morning and Evening star. Mercury also shows complete range of phase change like Moon and the planet Venus. Although Mercury is bright object on viewing from the Earth but its closeness to the Sun makes its observation difficult as compared to the Venus.

See also:

How do Venus and Mercury act as Morning and Evening star?

Mariner 10 was the first probe launched by NASA to visit the planet Mercury. It flew by Mercury in 1974 and 1975. After more than 30 years, another probe Messenger was sent by NASA to fly by in 2008 and 2009. In March 2011, it began to orbit Mercury. It is expected to explore the remaining parts of Mercury which could not be studied in the past mission.

The facts about the planet Mercury

  • Mercury is the smallest planet in our solar system.
  • Mercury is the closest planet to the Sun
  • The orbital velocity of Mercury is highest in all the planets.
  • The orbit of Mercury has highest eccentricity.
  • The axis of Mercury has smallest tilt in all the planets.
  • Mercury has no atmosphere and no moon.
  • In spite of being closest Mercury is not the hottest planet of our solar system.
  • The poles of Mercury have water in the form of Ice.

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