10 Amazing and Interesting Facts about Mercury.

As we all know, Mercury is the first planet in our solar system, first in the order of closeness to the sun. It has many facts and mysteries, and we have selected the best 10 amazing and interesting facts about mercury.

I am sure you must know many of those amazing and interesting facts about Mercury, but not all of them.

Amazing and Interesting Facts about Mercury

Some of those facts are related to its atmosphere and few are about geography. We even have added one or two points related to its core and the magnetic field. So, stay tuned at physicseverywhere.com

So, without wasting much we should start with our topic. Let’s start with the facts

A Metal Packed Planet

What is the radius of Mercury?

Well, it’s 2440 Kilometers. Now, what is the radius of its core?

Let me tell you, Mercury has core of radius 2074 Kilometers. Amazing, isn’t it?

Mercury is a core dominated planet. Its core has domination of 85% in its whole diameter. This is the first of the 10 amazing and interesting facts about Mercury.

If we compare this with other planets, none has such huge ratio. Following is a simple table, just take look.

PlanetDiameter of the Planet In KmCore DiameterRatio
Mercury2440207485%
Venus6052320053%
Earth6371352155%
Mars3390210062%
Jupiter699111600023%
Saturn582321250021%
Uranus256325126.420%
Neptune246224924.420%

According to this table, we can see the nearest competitor of Mercury in this respect is Mars which itself 23% lesser.

Smaller Than the Natural Satellites

Mercury has a radius of 2440 kilometers. We know this very well. There two moons in the solar system which have a wider diameter than the Mercury.

Which are those two moons? Obviously, the two largest one, Ganymede and Titan.

Titan has a mean radius of 2574 kilometers, which is around 5% larger than the Mercury.

Ganymede has a mean radius of 2634 kilometers which is around 7% larger than the Mercury.

So we can say, Mercury is a planet which smaller than a few Natural satellites. This is the second of the 10 amazing and interesting facts about Mercury.

Most Eccentric Orbit

Mercury is very strange in it’s orbit. One, it is the fastest planet on the orbit, two, it has the most eccentric orbit in all the planet of the solar system.

Following is a comparison table of Perihelion to Aphelion of all the planets.

But there is a question, do you know what are Perihelion and Aphelion?

Perihelion– It is the distance of planet to the sun on its orbit when it is closest.

Aphelion– It is the distance of planet to the sun on its orbit when it is farthest.

Mercury0.470.3166%
Venus0.730.7299%
Earth 1.020.9897%
Mars1.671.3883%
Jupiter5.464.9591%
Saturn10.129.0489%
Uranus20.1118.3391%
Neptune30.3329.8198%
Perihelion to Aphelion ration of each Planet. All the distances are measured in Astronomical Unit.

From the above table, it is clear that Mercury has an Aphelion 1.5 times greater than perihelion. All the other planets have almost equal perihelion and aphelion. This is the third of the 10 amazing and interesting facts about Mercury.

This eccentric orbit impacts a lot in other characteristics of Mercury.

Extreme Weather

We all know Mercury is the closest planet to the sun. Nearest to the sun makes an assumption that it should always have a hot temperature.

But it is not true. Mercury has a scorching weather as well as a chilled one.

There is nothing wrong in the sentence written above. It is absolutely correct. Mercury has both the conditions, scorching hot and chilling cool.

It is because of its eccentric orbit. It has a scorching hot temperature when it is nearest to the sun and having a day time. On it’s Aphelion and when it is night time, its temperature drops to a chilling cool.

Its temperature ranges from -173 degrees Celsius to 427 degrees Celsius. In the night time, it has a chilling temperature of -173 degrees Celsius and in the day time, its maximum temperature becomes 427 degrees Celsius. This is the fourth of the 10 amazing and interesting facts about Mercury.

A Day Longer Than a Year

There are two planets in the solar system that has a day longer than a year, and Mercury is one of those planets. Which one is other? This is a topic for another day.

How comes a day longer than a year? To get this understand, we first need to know what is a day and a year in the space.

A Day– A day on a planet is a period of time within which a planet completes a rotation on its axis, or a period of time to complete a day and night cycle. Here planets rotate like a top on its spindle.

A Year– A year on a planet is the time duration within which it completes an orbit around the sun. Here, planets revolve around the sun like an electron revolving around a nucleus.

Now, I hope you must have got the Idea of a day and a year. So, we are talking about a day on Mercury.

Well, Mercury completes an orbit in 59 earth days. So, it should have 59 earth days long day. But it is not like this.

Not all the rotation of mercury contains a day and a night. A day-night cycle on Mercury completes in 176 days. It is because of spin-orbit resonance with the sun. This resonance has a ratio of 3:2.

This means that on Mercury, there is 3 rotation for every 2 revolutions and it is tidally locked with the sun. Due to this locked condition, Mercury has one day-time for one revolution and night-time time for the other.

This two year period makes 176 earth days long day which is longer than a year which has only 88 earth days. This is the fifth of the 10 amazing and interesting facts about Mercury.

Fastest Planet on its Orbit

Mercury is the fastest planet to complete it’s orbit and the fastest moving planet on its orbit.

It is orbiting the sun at a velocity of 47.4 km/s. The nearest fastest planet is 36% lesser in speed. This is the sixth of the 10 amazing and interesting facts about Mercury.

By this speed, Mercury completes its orbit in 88 earth days which the lowest for any planet in the solar system.

PlanetsOrbital Velocity (km/s)
 MERCURY 47.4
 VENUS 35
 EARTH 29.8
 MARS 24.1
 JUPITER 13.1
 SATURN 9.7
 URANUS 6.8
 NEPTUNE 5.4
 PLUTO 4.7
This data fact is taken from https://nssdc.gsfc.nasa.gov/planetary/factsheet/index.html

Despite the closest, mercury is not the Hottest.

We all know that Mercury is the closest planet to the sun. As per the rules of the heat transfer methods Mercury must be the hottest planet in the solar system.

But it is not. You read it right, Mercury is not the hottest planet. This is the seventh of the 10 amazing and interesting facts about Mercury.

This title belong to Mercury’s neighbor Venus. Venus is the hottest planet of the solar system.

Why Mercury is not the Hottest Planet?

Well, it has three main reasons

  1. Eccentric Orbit– Although mercury is the closest planet to the sun but it does not get the same amount of heat for the entire year. On its aphelion and in the night time it’s temperature drops to -173 degrees Celsius.
  2. Faster Speed– Mercury has faster speed than Venus on its orbit as well as its axis. Due to the faster speed that Venus, the impact of heat of the sun is lesser on Mercury that Venus.
  3. Atmosphere- Mercury has almost no atmosphere. That’s why all the heat that comes to Mercury transfer to the surrounding areas. But Venus has a thick atmosphere that traps heat. This the biggest reason why Venus is the hottest planet.

Mercury has a maximum temperature of around 430 degrees Celsius during its day time which is even less that the mean temperature of Venus that is 464 degrees Celsius.

I hope you must have understood my point here.

Closest to the Sun

There is nothing much to say about this point as we all are reading from our childhood.

Mercury is the closest planet to the sun. Its mean distance from sun is 58 million kilometers. This is the eighth of the 10 amazing and interesting facts about Mercury.

PlanetsDistance from Sun (million km)
 MERCURY 57.9
 VENUS 108.2
 EARTH 149.6
 MARS 227.9
 JUPITER 778.6
 SATURN 1433.5
 URANUS 2872.5
 NEPTUNE 4495.1
 PLUTO 5906.4
This data fact is taken from https://nssdc.gsfc.nasa.gov/planetary/factsheet/index.html

Smallest Planet

As we have talked above, Mercury is the smallest planet in the solar system which is even smaller than the two of the biggest Natural Satellites.

Mercury became the smallest planet in the solar system when Pluto was abdicated from its title of being a planet. Pluto was reclassified as a dwarf planet in 2006. Before 2006, Pluto was the smallest planet of the solar system.

Mercury has a diameter of 4879 Kilometers which is the lowest among the planets. This is the ninth of the 10 amazing and interesting facts about Mercury.

PlanetDiameter (km)
 MERCURY 4879
 MARS 6792
 VENUS 12,104
 EARTH 12,756
 NEPTUNE 49,528
 URANUS 51,118
 SATURN 1,20,536
 JUPITER 1,42,984
Planets in the order of their diameter.
This data fact is taken from https://nssdc.gsfc.nasa.gov/planetary/factsheet/index.html

Tidally Locked With the Sun

Mercury is the only planet in the solar system which tidally locked with the Sun.

Before going any further we should know what is a tidally locked object?

When two objects closed in such system that they faces the same side each time. For example, we always see the same side of the moon that mean moon and the earth are tidally locked.

Just like moon and earth, Mercury and the sun are tidally locked with each other. But here in case of Mercury there is a twist. Like moon to earth, Mercury and sun are not facing the same side always. Rather it changes after every revolution mercury completes.

This tidally locked situation is the reason Mercury has a day twice of its year.

Mercury has a spin-orbit resonance ratio of 3:2 which means at every 3 rotation Mercury completes 2 revolution. This is the tenth of the 10 amazing and interesting facts about Mercury.

Conclusion

Well, here we have discussed 10 amazing and interesting facts about Mercury, Although it has a long list of amazing facts still to be explored.

Till now, only two spacecrafts have reached to Mercury one is Mariner 10 and the other is Messenger. Anything that we discussed here is the data collected by these two spacecrafts only.

We have got a better technology today, so we could expect more data to be collected in the future about Mercury. Till then explore it on your own.


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