Mercury is a terrestrial planet that is popular for being the smallest planet in the solar system. It was first observed by Galileo Galilee in the year 1631. Besides being the smallest of all the planets, it also shares closest proximity with the Sun. Mercury is so small that it is just a little larger than Earth’s moon. Since mercury is really small and close to the Sun, the Sun would appear three times bigger than that on Earth. Here, we are going to discuss the characteristics of Mercury along with interesting facts of Mercury for kids.

Composition of Mercury

Mercury is a terrestrial planet, pretty much like Earth. It has a solid crust, mantle, and core and is mostly rocky. It is said that Mercury was formed about 5 billion years back. The gravity pulled the dust particles and various gases in one place and formed this little planet called Mercury. However, today, mercury is a rocky planet with most of what it is made of being solid.

The core of mercury covers approximately 85 percent of its radius. The metallic substances present in the center make up the core of Mercury. While the core is so thick, the mantle and the crust only account for 12 percent of the remaining radius. It is also said that the core of Mercury contains metallic substances in both liquid/molten form and solid form.

Weather Conditions

A lot of people have a misconception that Mercury must be the hottest of all planets for its proximity with the sun. However, mercury is not the hottest planet in the solar system. Venus makes the hottest planet in the solar system, after which it is Mercury. The reason why Mercury is not the hottest planet is because it is very dense. It is at least so dense that despite being closest to the Sun, it lets Venus be the hottest planet.

However, Mercury definitely is quite a hot planet. It has extreme temperatures- both cold and hot. The days are extremely hot while the nights are extremely cold. In the day time, the temperature on Mercury rises up to 430 degrees Celsius. However, in the night time it falls as low as -180 degrees Celsius.

Mercury also contains water, mostly in the form of ice at the north and south poles. Even at the poles, the craters that have a permanent shadow and low temperatures are the only place that can capture water ice.

Mercury does not witness seasonal changes or even seasons like other planets. Since the tilt in the axis of rotation for Mercury is really less (just 2 degrees), it has a perfect upright spin, unlike other planets.


Mercury appears to be a shade of grey or brown, with the craters looking bright. Mercury has most craters out of all planets. If you wonder how that might look, it shares resemblances with how moon looks to great extent. These craters were created because of the meteors, meteoroids, and comets hitting the planet surface and creating hollow spaces.

When these celestial bodies hit the surface of Mercury, a lot of energy is emitted as a result. While larger pieces from the collision fly and fall at a distance, the finer particles stay right there. These fine particles are the reason why the crate has a bright hue compared to the other parts of the surface. The craters on Mercury are treated specially. This is why most of them get the names of famous artists, authors, and writers who passed away.

Mercury has smooth plains as well as rocky cliffs. The contractions that took place on the planet surface over a period of millions of years led to the formation of these rocky cliffs.


As already discussed, Mercury is the closest planet to the Sun. The distance between Earth and Sun is one astronomical unit. Talking in the terms of distance between Sun and Earth, Mercury is just 0.4 astronomical unit away from the Sun. This means it is just one-fourth astronomical units from the Sun. In terms of miles, it is about 36 billion miles away from the Sun.

Rotation and Revolution

Despite being a very small planet, mercury is really slow at taking a rotation. This is why; it takes one rotation in 59 earth days, which is very slow. Another unusual thing about Mercury is that it does not have a definite sunrise and sunset like other planets. While for other planets the start and end of one rotation marks sunrise and sunset, it is different for this planet. For Mercury, the sun rises, sets, and rises again at different regions throughout the rotation. The sunset follows this pattern as well.

The orbit of Mercury assumes an egg-like shape. This means Mercury has a high level of eccentricity. This is why despite being so close to the Sun, Mercury takes its own sweet time to complete its revolution. It takes 88 earth days for Mercury to complete its one revolution. However, it still is not as bad because Mercury revolves around the Sun at a great speed. In fact, the speed of Mercury at revolving is the highest compared to other planets. This is why Mercury has been named after the Roman God of travelers or the Roman messenger God.

Fun Facts of Mercury for Kids

Mercury, being the smallest member of the solar system, has a number of interesting characteristics. Pretty much like any other planet, Mercury is unique in its own ways. Here are some interesting facts of Mercury for kids.

  1. Mercury does not have an atmosphere like other planets. The atmosphere of any planets helps in trapping heat in the planet. However, since Mercury does not have an atmosphere, this is why Mercury is not the hottest planet. Since Venus has an atmosphere, it has the ability to trap heat and that is why it is the hottest planet.
  2. One of the most interesting facts of Mercury for kids is that despite being really close to the Sun, Mercury becomes extremely cold at nights. This, again is because mercury does not have an atmosphere and does not trap heat. If at all Mercury had an atmosphere, it would have been able to trap heat and not be so cold at nights.
  3. You can observe Mercury from Earth 13 times in one hundred years. This is because Mercury is in its transit phase during this time. Transit means Mercury passing across the face of the Sun. This is when it is visible.
  4. People have named Mercury as the morning or evening star. It is so because you can very clearly see Mercury during the time right before the sunrise and right after the sunset.
  5. There have only been two spacecrafts that have reached Mercury. The reason why only two spacecrafts reached Mercury is because it is very close to the Sun. Because of its closeness to the Sun, it becomes very difficult for the spacecrafts to stand so much of heat.
  6. Mercury has the most non circular and eccentric orbit, out of all the planets. This is why it takes it a lot of time to complete its revolution. However, thanks to Mercury’s incredible speed because of which it completes its revolution in just 88 days.
  7. Another facts of Mercury for kids is that Mercury does not have seasons. This is because the axis of Mercury has a very less tilt, which makes it rotate in an upright fashion.
  8. Ever since scientists discovered Mercury till now, they report of observing shrinkage in the size of this planet. Since its formation, Mercury has lost 1.5 kilometers of its original diameters. This has happened as a result of the process of solidification of the core. as the core of Mercury cools down and solidifies, it contracts over a period of time.
  9. ESA is planning to launch yet another spacecraft to Mercury in a joint mission with Japan Aerospace Exploration Agency. The scientists call this mission as “BepiColombo”- getting its name from Giuseppe Bepi Colombo who is a famous mathematician. The spacecraft will be launched this year. Also, the spacecraft will take about 7 years to reach the orbit of Mercury.
  10. Pretty much like Jupiter, Saturn, Venus, and Mars, Mercury is also visible to the naked eyes without needing a telescope. This is a mind-boggling fact since mercury is really small in size.
  11. Mercury neither has moons nor does it have rings around it. In kid facts about Venus said that just Mercury and Venus that don’t have even a single moon. This is why, at night time, Mercury does not have any illumination at all.

These are some of the fun facts of Mercury for kids. Mercury is one such planet which would never support life for humans no matter how facts of Mercury for kids make it look interesting. The reasons are quite apparent. It would be too hot and too cold for humans to exist. You would be reduced to ashes even as you try soaring too close to Mercury has the potential to reduce you to ashes. In fact, even most metallic spacecrafts can’t stand so much of heat and melt as a result. Besides this, absence of atmosphere in Mercury is yet another reason for it not being able to support life.


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