Mercury, named after the Roman deity as the ‘messenger of gods’ is the smallest planet in the family of our Solar System. It has been entitled with this name because it revolves with the fastest speed around the Sun just as the divinity after which it is named was the swiftest of all other deities. This celestial body has been known by the inhabitants on Earth from at least the time of Sumerians, around 5,000 years ago. In first look, its appearance seems to be same as the moon, but appearances can be deceiving. Mercury, like any other planet of our solar system, has been the centre of fascination of many scientists. Over the years, the progress that has been made in the field of space exploration has also brought in heaps of information about Mercury as well, revealing this first planet to the population on Earth. Here, we have mentioned a few interesting facts about the Mercury, to acquaint you with it.
Distance From Sun: 35,983,095 miles (57,909,178 kms)
Distance From Earth: 77.3 x 106km (Minimum), 221.9 x 106 km (Maximum)
Mean Radius: 2,439.7 km
Mean Circumference: 15, 329.1 km
Volume: 60,827,208,742 km3
Mass: 3.301 x 1023 kg
Density: 5.427 g/cm3
Surface Area: 74,797,000 km2
Surface Gravity: 3.7 m/s2
Length of Day: 1,407. 5 hours, 30 minutes
Length of Year (Orbital Period): 87.97 days
Number of Moons: 0
Average Orbit Velocity: 170,503 km/h
Orbit Inclination: 7.0 degrees
Orbit Circumference: 359,976,856 km
Average Temperature: 173/427 °C
Interesting And Fun Facts About Mercury
- Mercury is the second densest planet in the solar system after the Earth. It has a density of 5.43 gm/cm3.
- Mercury is one of the five planets which were also known to the ancient people and all these five planets were named as wandering stars.
- Mercury is named after the swiftest of the ancient Roman Gods, the ‘messenger of gods’.
- Mercury is closest to the Sun but it is very difficult to observe from the Earth as it is only one-third in diameter in comparison to the Earth. In addition to this, when Mercury is close to the horizon, the interference created by the atmosphere of the Earth lessens the visibility even with the finest telescope. It can only be analysed during the day time or at the time of sun rise or sun set.
- Mercury has no satellites.
- Mercury can also be observed during the twilight and can also be observed in an event called transit, when it passes across the face of the Sun. These unusual transits fall around 8th May and 10th November. The first two transits of Mercury in the 21st century took place on 7th May 2003 and 8th November 2006. The next will occur on 9th May 2016.
- The iron core of the Mercury has a radius of 1,800 to 1,900 km and the outer shell is only 500 to 600 km thick.
- At first sight, the surface of the Mercury looks similar to that of the Moon but there are some differences. On this planet, the most heavily cratered regions, known as cratered terrain, have fewer craters than the highlands of the Moon.
- The Caloris Basin is one of the biggest impact basins in the Solar System and is also the most observed feature on this planet so far. This Basin is 1,550 km in diameter and the spacecraft known as Mariner 10 could only image half of the basin; the other half was covered by darkness.
- This basin was the result of an asteroid collision on the surface of the Mercury in the early history of Solar System. Over the many billion years, this planet shrank in radius about 1 to 2 km as the planet cooled to attain its present size. The outer crust shrunk and became strong to protect magma from reaching the surface, finishing the time of volcanic activity.
- On Mercury, there are long, sinuous scarps or cliffs known as lobate scarps. Lobate scarps seems to be the surface expression of thrust faults, where the crust is broken besides a leaning surface and pushed upward.
- The biggest known lobate scarp on this planet is Discovery Rupes (rupes refers to cliff in Latin). It is about 550 km long with a height of 1.5 km.
- Earlier, it was thought that Mercury’s same side always faces the Sun but in 1965 the astronomers found that this planet rotates three times for every two orbits. It revolves around the Sun every 88 days, going through the space at about 50 km per second faster than any other planet of the solar system. The length of the sidereal rotation of Mercury is equal to 58.646 Earth days.
- The orbit of the Mercury is highly eccentric as it is only 46 million km at perihelion from the Sun; however, it is 70 million km at aphelion. The location of the perihelion rotates very slowly around the Sun. If one could be there on the scorching surface of Mercury when it nearest to the Sun then, at that time, the Sun would be nearly three times as big as it is when observed from the Earth.
- The variations in temperatures on Mercury are the largest in our entire Solar System, varying from 90 k to 700 k. In addition to this, it has a small magnetic field which has strength of nearly about 1% of the magnetic field of Earth. However, Mercury has no satellites.
- Mercury, being at a closest distance from the Sun gets overheated during day time, whereas at night, the temperature goes down hundreds of degrees below the freezing point.
- The atmospheric composition of Mercury is 42% Oxygen, 29% Sodium, 22% Hydrogen, 6% Helium, 0.5% Potassium, and also, there are possible traces of Argon, Carbon dioxide, Water, Xenon, Nitrogen, Neon, Krypton, Magnesium and Calcium.
- Pierre Gassendi used a telescope in 1631 to observe Mercury from the Earth as it crossed the face of the Sun.
- The signs of ice locked in the polar areas of this planet were discovered in 1991 by the scientists using the Earth-based radar.
- The first spacecraft which was sent on Mercury was Mariner 10, which imaged nearly 45% of the total surface of this planet.
- MESSENGER spacecraft is the first one to orbit this planet. It was sent earlier in 2008 and 2009 and at that time, it completed two close flybys of Mercury.
- The upcoming mission to Mercury is BepiColombo – ESA/JAXA Orbiter Mission which will begin in 2013.