10 strange facts about the planet Mercury
Mercury is an interesting planet. The first planet to orbit our star, the Sun, Mercury, has been largely ignored in the public eye over planets like Mars. However, recent information collected by the MESSENGER spacecraft indicates that Mercury may be just as fascinating as Mars, if not more so. If NASA or other space agencies ever want to return to our first planet, the public needs to know why such a space journey might be worthwhile. Can people live on Mercury? Maybe not, but there are indications that that idea is not as far-fetched as it initially seems.
With the advent of commercial space companies like SpaceX, new missions to Mercury may be something people can try again. One of the biggest challenges of spaceflight is cost, and with increasing competition and availability of technology, the cost of spaceflight is coming down. The last mission to Mercury was NASA's MESSENGER spacecraft in 2008.
Why should humanity continue to explore Mercury and the rest of the solar system? There are some excellent reasons why Mercury continues to be an interesting target for scientific and astronomical research.
Related: Top 10 things to know about asteroid collisions with Earth
10 Mercury is closer than all the planets to the Sun except Earth
Mercury is heavy, which is useful to remember. Why? Mercury has a dense core of molten iron. When people travel to another object in the solar system, they encounter the effects of zero or low gravity. Low-gravity environments wear out the human body, which functions best on the planet on which humans were born, 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 comparable to Mars, a larger planet in terms of size. Mercury's relatively high gravitational field, while lower than Earth's, could make it 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 does not stand out as the hottest. That title goes to Venus, the second planet from the sun. Mercury does not have a thick atmosphere. The atmosphere is what astronomers call an exosphere, very sporular with little gas content. Nevertheless, Mercury receives enormous radiation from the Sun, which is on average 36 million miles or 58 million kilometers away from our star.
The temperature of Mercury on the side facing the Sun can reach 427°C. Venus, the hottest planet in the solar system, has an even more unpleasant climate than Mercury, with average temperatures of 467°C on its surface. Mercury's thin exosphere prevents the heat from keeping Mercury warm, as it can drop to -170°C on the side facing away from the Sun.[2]
8 No human probe has ever landed on Mercury
Mercury has never had human visitors. This is because the ability to travel into space is only something humanity has been able to do for the past 60 years. Although our technology is still primitive, the ongoing debate over whether humans should travel to other planets continues.
Most people are fixated on the moon and Mars as a likely target. However, there is also the possibility of building a balloon cloud city on Venus and a crater city on Mercury to study the sun. The rise of well-funded spaceship companies like SpaceX could open doors to send people to places they've never been before, including the first planet, Mercury.[3]
7 Mercury provided evidence for the general theory of relativity
The planet Mercury has an orbit that is a distinct ellipse. As Mercury orbits the Sun, its distance from the Sun varies by 14 million miles. Mercury's elliptical orbit has the most eccentricity of any major planet in our solar system. In plain language, this means that 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 gravity predicted and how the orbit preceeded, or wobbled, as Mercury traveled around the sun several times.
Albert Einstein's general theory of relativity correctly explains the actual behavior of Mercury's orbit. According to a statement from the University of Central Florida, Einstein's general theory of relativity predicts that the precession, or wobble, of Mercury's orbit will be greater than what Newton's laws of gravity predicted. That's what astronomers observe when they measure Mercury's orbit.[4]
6 Mercury has a thin atmosphere with oxygen and sodium
Although it looks a bit like our moon, more recent observations of Mercury have provided information that the moon's core structure and surface exhibit more variation than the moon's. Mercury is heavier than Earth's moon because of its iron core, and its thin atmosphere contains oxygen and sodium. However, Mercury's atmosphere is not sufficient for breathing.
Nevertheless, oxygen in Mercury's atmosphere is a fascinating discovery that could help future technology if humans ever explore Mercury. It is possible that the oxygen on Mercury could be captured and compressed for use by astronauts. Based on data from NASA MESSENGER spacecraft, oxygen comprises 42% of Mercury's thin atmosphere.[5]
5 Mercury is the smallest planet
Mercury is a small and heavy planet. If Mercury were the size of a golf ball, Earth would be about the size of a grapefruit. Mercury is the smallest of the solar system's eight major planets. It has a diameter of 3,032 miles (4,880 kilometers).
Although Mercury is small compared to our planet Earth's diameter of 12,760 kilometers (7,926 miles), Mercury is still a large object that would take a long time for human astronauts or robotic rovers to fully explore. Any rover that spent more than a few months on the planet would probably need to be powered by a small nuclear isotope generator, especially if it were to visit Mercury's shadow side or its craters.[6]
4 To human eyes, Mercury would appear dark gray
What you see depends on the 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 make Mercury appear dark gray to a human observer.
To an alien observer who had infrared vision, half of Mercury would glow very brightly because it absorbs a lot of heat from the nearby sun. The other half would be dark. Mercury would be a relatively dull and boring world for humans to live in. Still, there could be plenty of opportunities 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 spacecraft found evidence in 2008 that there is water ice in Mercury's dark large craters. This water ice could come from Mercury, or could be the result of comets hitting Mercury. Water ice on the planet closest to the sun seems quite strange.
However, the presence of water ice on Mercury could make it possible to provide coolant and hydration to future human space explorers visiting Mercury. Without water, it is difficult to sustain permanent life on the Earth's surface. Terraforming or aquaponic agriculture will only be 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 chrome to make stainless steel and shiny plating for our classic cars. Lining spacecraft with stainless steel protects them from corrosion when they come into contact with seawater when they land in Earth's oceans. SpaceX famously makes its Falcon and Starship rockets from stainless steel, which contains chromium in its chemical composition. In the future, Mercury could be an ideal place for mining the element, as Mercury contains a lot of chromium.
The percentage of chromium on Mercury is greatest in its heavy core. Chromium resists corrosion, which is a problem in structures and vehicles exposed to outdoor weathering and toxic acids. According to data from the MESSENGER spacecraft, the average amount of chromium on Mercury's surface is 200 parts per million.[9]
1 Mercury has a gigantic impact crater
Mercury is very susceptible to impacts from objects such as asteroids and comets because of its thin atmosphere, which does not provide much protection. Mercury's surface is covered in craters, some of which are gigantic. The surface resembles Earth's moon, which is also heavily weathered by craters. One of the large craters is called the Rembrandt crater. It is 444 miles (715 kilometers) wide.
This monster crater was photographed by the MESSENGER spacecraft in 2008. Whether an asteroid or a comet created this large crater remains unknown, but the impactor was likely larger 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]