10 Strange Facts about the Planet Mercury

Mercury is an interesting planet. The first planet orbiting our star, the Sun, Mercury has been largely ignored in the public eye over planets like Mars. However, recent information gathered from the MESSENGER space probe indicates that Mercury may be just as fascinating as Mars, if not more so. If NASA or other space agencies are ever to return to our first planet, the public must know why such a space trip might be worthwhile. Could humans live on Mercury? Maybe not, but there is evidence for that idea not being as far-fetched as it initially seems.

With the advent of commercial space companies like SpaceX, perhaps new missions to Mercury could be something that humans may try again. One of the main challenges of spaceflight is the cost, and with increasing competition and availability of technology, the costs of spaceflight are going down. The last mission to Mercury was the MESSENGER space probe by NASA in 2008.

Why should humanity keep exploring Mercury and the rest of the solar system? There are some excellent reasons why Mercury still makes an interesting target for scientific and astronomical research.

Related: Top 10 Things You Should Know About Asteroid Collisions With Earth

10 Mercury Is Denser than All the Sun’s Planets except Earth

Mercury is heavy, which is a helpful thing to remember. Why? Mercury has a dense core made of molten iron. Whenever humans travel to another object in the solar system, they have to contend with the effects of zero or low gravity. Low gravity environments wear out the human body, which functions best on the planet humans were born on, Earth.

Despite its small size, Mercury has a gravitational acceleration of 9.85 feet per second squared (3.7 meters per second squared). That is similar to Mars, a larger planet by size. Mercury’s relatively high gravitational field, though lower than Earth’s, could allow it to be a target for human exploration sometime in the future.^[1]

9 Mercury Is Cooler than Venus

Mercury is the closest planet to our star, the Sun, but it does not hold the distinction of being the hottest. That title goes to Venus, the second planet from the Sun. Mercury lacks a thick atmosphere. Its atmosphere is what astronomers call an exosphere, very trace with little gas content. Nevertheless, Mercury receives enormous radiation from the Sun, being an average of 36 million miles or 58 million kilometers away from our star.

Mercury’s temperature on the side facing the Sun can get up to 800°F (427°C). Venus, the hottest planet in the solar system, has an even more unpleasant climate than Mercury, with average temperatures reaching 872°F (467°C) on its surface. Mercury’s thin exosphere prevents the heat from keeping Mercury hot, as it can fall to temperatures of -275°F (-170°C) on the side facing away from the Sun.^[2]

8 No Human Probe Has Ever Landed on Mercury

Mercury has never had any human visitors. This is because the ability to travel into outer space has only been something humanity has been capable of for the past 60 years. Although our technology is still primitive, the ongoing debate about whether humans should travel to other planets continues.

Most people are fixated on the Moon and Mars as a probable target. However, there is also the possibility of building a balloon cloud city on Venus and a crater pod city on Mercury to study the Sun. The rise of well-funded spaceship corporations like SpaceX may open doors to sending humans where they have never gone before, including to the first planet, Mercury.^[3]

7 Mercury Gave Evidence for the Theory of General Relativity

The planet Mercury has an orbit that is an obvious ellipse. As Mercury orbits the Sun, its distance from the Sun varies by 14.3 million miles (23 million kilometers). The elliptical orbit of Mercury has the most eccentricity of any major planet in our solar system. In normal language, that means the oval of Mercury’s orbit is longer and less circular than the other seven planets in the solar system.

Early measurements of Mercury’s orbit showed a difference between what Newton’s theory of gravitation predicted and how the orbit precessed or wobbled as Mercury traveled multiple times around the Sun.

Albert Einstein’s theory of general relativity explains the actual behavior of Mercury’s orbit correctly. According to an explanation provided by the University of Central Florida, Einstein’s theory of general relativity predicts that precession or the wobble of Mercury’s orbit will be larger than what Newton’s gravitational laws predicted. That is what astronomers observe when they measure the orbit of Mercury.^[4]

6 Mercury Has a Thin Atmosphere with Oxygen and Sodium

Although it looks kind of like our moon, more recent observations of Mercury have yielded information that it has more variety in its core structure and surface than the moon does. Mercury is heavier than Earth’s moon because of its iron core and its thin atmosphere has oxygen and sodium. However, Mercury’s atmosphere is not sufficient to breathe.

Nevertheless, oxygen in the atmosphere of Mercury is a fascinating discovery that may help future technology if humans ever explore Mercury. It is possible the oxygen on Mercury could be captured and compressed for the use of astronauts. Based on NASA MESSENGER space probe data, oxygen comprises 42% of Mercury’s thin atmosphere.^[5]

5 Mercury Is the Smallest Planet

Mercury is a small and heavy planet. If Mercury was the size of a golf ball, the Earth would be about the size of a grapefruit. Mercury is the smallest of the eight major planets of the solar system. It has a diameter of 3,032 miles (4,880 kilometers).

Although Mercury is small compared to our planet Earth’s diameter of 7,926 miles (12,760 kilometers), Mercury is still a large object that would take a long time for human astronauts or robotic rovers to explore fully. Any rover that spent more than a couple of months on the planet would probably need to be powered by a small nuclear isotope generator, particularly if it was visiting the shadow side of Mercury or its craters.^[6]

4 To Human Eyes, Mercury Would Look Dark Grey

What you see depends on what type of eyes or camera you have. As the saying goes, “Beauty is in the eye of the beholder.” The different wavelengths of electromagnetic radiation coming from the Sun would end up making Mercury look dark grey to a human observer.

To an alien observer who had infrared vision, half of Mercury would glow very bright because it absorbs a lot of heat from the nearby Sun. The other half would be dark. Mercury would be a relatively drab and boring world for humans to live in. Still, there could be plenty of opportunity to collect light energy for solar panels to power future space bases.^[7]

3 There Is Water in the Form of Ice on Mercury

The MESSENGER space probe in 2008 found evidence that there is water ice in the dark large craters of Mercury. This water ice could be native to Mercury, or it could be the result of comets hitting Mercury. Water ice on the closest planet to the Sun seems rather odd.

However, the presence of water ice on Mercury could make it possible to provide coolant and hydration to future human space explorers who visit Mercury. Without water, it is hard to sustain permanent life on a planet’s surface. Terraforming or aquaponic agriculture is only possible in future space bases if water is present or brought to a planet from Earth.^[8]

2 There Is the Element Chromium on Mercury

We like to use chromium to make stainless steel and shiny plating for our classic cars. Plating spacecraft with stainless steel protects them from corrosion when encountering seawater when they land in Earth’s oceans. SpaceX famously makes their Falcon and Starship rockets from stainless steel, which includes chromium in its chemical makeup. In the future, Mercury might be an ideal place for the mining of the element because Mercury has a lot of chromium.

The percentage of chromium on Mercury is the greatest in its heavy core. Chromium is resistant to corrosion, which is a concern with structures and vehicles exposed to outdoor weathering and toxic acids. The average abundance of chromium on Mercury’s surface, according to the MESSENGER space probe’s data, is 200 parts per million.^[9]

1 Mercury Has a Giant Impact Crater

Mercury is very susceptible to impacts from objects like asteroids and comets because of its thin atmosphere, which does not provide much shielding. Mercury’s surface is covered with craters, some of which are gigantic. Its surface looks similar to Earth’s moon, which is also heavily weathered by craters. One of the big craters is called the Rembrandt crater. It is 444 miles (715 kilometers) across.

This monster crater was photographed by the MESSENGER space probe in 2008. Whether an asteroid or comet made this big crater remains unknown, but the impactor was probably bigger than a skyscraper. Craters are better places to build space bases on hot planets because shadows protect life forms from excessive radiation from a star like the Sun.^[10]