Planet Mercury Facts for Kids

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 the 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.

The planet Mercury is the first in the Solar System line-up, meaning it is closet to the Sun. It moves very quickly across the sky and so was named Mercury, which in Roman mythology was the god of commerce, travel, and thievery.

Mercury is small and rocky and makes its trip around the Sun once every 88 days. Faster than any other planet, mercury travels at almost 50 km per second. Its highly elliptical orbit places Mercury between 47 million km and 70 million km from the sun at different positions. This causes temperatures on the surface to reach as high as 467 degrees Celsius, and as low as -183 degrees Celsius, due to the very small atmosphere. This highly eccentric orbit confused 19th-century astronomers until Einstein’s General Theory of Relativity was found to correctly predict the motions of Mercury. These accurate predictions were important in the early acceptance of Einstein’s theory.

Mercury is always very near the sun and therefore, difficult to see in the twilight sky, but it is often visible with binoculars and sometimes can be seen with the naked eye. The illumination of Mercury’s disk varies when viewed with a telescope from Earth because it is closer to the Sun than the Earth.

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 that 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 places 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 the moon looks to a 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.

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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 terms of the 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 mark 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 spacecraft that have reached Mercury. The reason why only two spacecraft reached Mercury is that it is very close to the Sun. Because of its closeness to the Sun, it becomes very difficult for the spacecraft to stand so much heat.
  6. Mercury has the most noncircular and eccentric orbit, out of all the planets. This is why it makes 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, the 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.
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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 spacecraft can’t stand so much of heat and melt as a result. Besides this, the absence of atmosphere in Mercury is yet another reason for it not being able to support life.

Mercury: The Possible Result of a Hit-and-Run

According to one theory, Mercury was created after a giant asteroid collided with an even more massive object about 4.5 billion years ago. This collision formed the planet now known as Mercury and also shot a large amount of debris into space.

This idea that Mercury was the result of a collision was stemmed from the fact that the rocky planet has an unusual amount of metal for its size. Apparently, after the impact, the outer layers were stripped off, and very little of those outer layers reattached, thus creating a fragile shell and a dense core. Scientists have examined the apparent collision with the aid of computers and looked at the anatomy of the crash, as well as how some of the impact debris ended up on Venus and Earth. Earth’s moon was also the result of an impact, as was Pluto and its moons.

After examining the computer simulation, scientists were able to able to follow the formation of Mercury and determine the composition of the two colliding bodies, as well as follow the fragments that were the result of the collision for millions of years until they either came into contact with a planet, the sun, or were ejected from the inner solar system. This is how they were able to determine that some of the ejected material landed on Earth as well as Venus. The simulation also discovered that it would take 4 million years for only half the particles to land back on Mercury if they all fell back, but by that time the debris would have been carried off by solar radiation which explains why Mercury didn’t keep much material on its outer shell.

Many planets and articles in space were created as a result of collisions. Dust in the early solar system became rock and eventually the planets we know today. Scientists believe many objects collided and became one more massive object, while others were disintegrated or became dramatically altered after as much as a glancing blow. Planets may lose their crust, or atmosphere, or can be ripped apart to form smaller objects or moons to other worlds. These impacts create fragments that could become the space rocks that land on Earth today. The moon was thought to have been created when a Mars-sized object slammed into our planet.

The solar system was created shortly after the Sun’s formation about 4.6 billion years ago. Scientists believe that the dust and gas that orbited the Sun gathered to form rocks. Those rocks collided and joined to form comets and asteroids, and eventually planets. Scientists believe there may have been as few as 100 or so objects no more substantial than the Moon or Mars responsible for forming our planets, but their cosmic collisions would have created dramatic results. When gravitational forces are taken into account with massive objects even passing near each other, extreme changes to both bodies can take place. Each object can be decompressed, melted, lose material, or also destroyed. The smaller object’s gravity could easily depressurize in the presence of a more massive object causing the smaller of the two to break apart. This can cause the formation of asteroids and meteorites.

What’s left of Mercury after this apparent hit-and-run collision is a large and dense core surrounded by a fragile mantle and crust; however, scientists still don’t fully understand the complexities of this theory and are still examining it with the help of computer models and simulations.

The hit-and-run theory may, however, explain the extremely diverse composition of asteroids, including pieces that fall to Earth as meteorites. Some resemble the rocky surfaces of planets, but others are filled with iron, which is much more like the core of a world. This diversity would account for the theory that all space rock was not formed in the same disk of debris; instead, it has been created as a result of many different collisions in space and therefore contains different types of material.

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