Mercury the Closest Planet to the Sun

Whenever we talk about the closest planet to the sun, our answer is always Mercury. Yeah, you get it right, today we are going to talk about Mercury the closest planet to the sun.

Mercury, the closest planet to the sun is not only the closest but also the smallest planet in our solar system. It is only slightly larger than Earth’s Moon.

Standing on the surface of Mercury, we would experience the Sun more than three times as large as it does when viewed from Earth. As far as the sunlight concerns it appears 7 times much brighter.

As we discussed, it is the closest planet to the Sun. The closest but not the hottest. The hottest planet of the solar system title belongs to Venus, and it is due to its dense atmosphere.

Mercury is the fastest planet, zipping around the Sun every 88 Earth days.

Mercury is appropriately named for the swiftest of the ancient Roman gods.

Size and Distance

Being the smallest planet of the solar system, Mercury has a radius of 2,440 kilometers. It is a little more than 1/3 the width of Earth.

Considering Earth as the size of a nickel, Mercury would be about as big as a blueberry.

Mercury is entitled to the closest planet to the sun that has an average distance of 58 million kilometers. In terms of the Astronomical Unit, Mercury is 0.4 astronomical units away from the Sun.

One astronomical unit (abbreviated as AU), is the distance from the Sun to Earth.

From this distance, it takes sunlight 3.2 minutes to travel from the Sun to Mercury.

Orbit and Rotation

Mercury the closest planet to the sun has a highly eccentric, egg-shaped orbit. Its closest distance from the sun is 47 million kilometers and the farthest one is as distant as 70 million kilometers.

Mercury orbits around the Sun every 88 days. It is keep traveling through space at nearly 47 kilometers per second, faster than any other planet.

Mercury is the fastest on its orbit but very slow on its axis. It spins on its axis very slowly and completes one rotation in 59 Earth Days.

Moving faster in its elliptical orbit, and the closeness from the Sun, Mercury’s each rotation do not experience both sunrise and sunset like other planets.

The morning sun appears to rise briefly, set, and rise again from some parts of the planet’s surface. The same thing happens in reverse at sunset for other parts of the surface.

Due to the phenomenon mentioned above, One Mercury solar day (one full day-night cycle) equals 176 Earth days—just over two years on Mercury.

Mercury’s axis of rotation is tilted just 2 degrees with respect to the plane of its orbit around the Sun. That means it spins nearly perfectly upright and so does not experience seasons as many other planets do.


Mercury has formed about 4.5 billion years ago when gravity pulled swirling gas and dust together to form this small planet nearest the Sun.

Like its fellow terrestrial planets, Mercury has a central core, a rocky mantle and a solid crust.



Mercury is the second densest planet, after Earth.

It has a large metallic core with a radius of about 1,289 miles (2,074 kilometers), about 85 percent of the planet’s radius. There is evidence that it is partly molten or liquid.

Mercury’s outer shell, comparable to Earth’s outer shell (called the mantle and crust), is only about 400 kilometers (250 miles) thick.


If we talk about the surface of Mercury, it somewhat similar to that of Earth’s moon.

It is scarred by many impact craters resulting from collisions with meteoroids and comets just like the earth’s moon.

Very large impact basins, including Caloris (960 miles or 1,550 kilometers in diameter) and Rachmaninoff (190 miles, or 306 kilometers in diameter), were created by asteroid impacts on the planet’s surface early in the solar system’s history.

While there are large areas of smooth terrain, there are also cliffs, some hundreds of miles long and soaring up to a mile high. They rose as the planet’s interior cooled and contracted over the billions of years since Mercury formed.

Most of Mercury’s surface would appear greyish-brown to the human eye. The bright streaks are called “crater rays.” They are formed when an asteroid or comet strikes the surface.

The tremendous amount of energy that is released in such an impact digs a big hole in the ground and also crushes a huge amount of rock under the point of impact.

Some of this crushed material is thrown far from the crater and then falls to the surface, forming the rays. Fine particles of crushed rock are more reflective than large pieces, so the rays look brighter.

The space environment—dust impacts and solar-wind particles—causes the rays to darken with time.

A Diverse Temperature Range

Temperatures on the surface of Mercury are extreme, both hot and cold.

During the day, temperatures on Mercury’s surface can reach 800 degrees Fahrenheit (430 degrees Celsius).

Because the planet has no atmosphere to retain that heat, nighttime temperatures on the surface can drop to minus 290 degrees Fahrenheit (minus 180 degrees Celsius).

Mercury may have water ice at its north and south poles inside deep craters, but only in regions of permanent shadow.

There it could be cold enough to preserve water ice despite the high temperatures on sunlit parts of the planet.


Instead of an atmosphere, Mercury possesses a thin exosphere made up of atoms blasted off the surface by the solar wind and striking meteoroids.

Oxygen, sodium, hydrogen, helium, and potassium is the main composition of Mercury’s Exosphere.

Potential for Life

Mercury’s environment is not conducive to life as we know it. The temperatures and solar radiation that characterize this planet are most likely too extreme for organisms to adapt to.


Mercury’s magnetic field is offset relative to the planet’s equator.

Though Mercury’s magnetic field at the surface has just one percent the strength of Earth’s.

Due to this weak magnetosphere, it interacts with the magnetic field of the solar wind to sometimes create intense magnetic tornadoes that funnel the fast, hot solar wind plasma down to the surface of the planet.

When the ions strike the surface, they knock off neutrally charged atoms and send them on a loop high into the sky.

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