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Can Humans Live on Mercury?

No, humans can not live on Mercury due to extreme temperature fluctuations, solar radiation, and a thin atmosphere.

Josh Universe
Dec 19, 2022
6 min read
Solar SystemPlanetary Colonization

Mercury is a harsh environment, being the closest planet to our Sun. Mercury, the closest planet to our Sun, is not actually the warmest planet in the group, but Mercury has some of the most extreme variations in temperature. Mercury is the closest planet to the Sun -- without any real atmosphere -- and is a scorching, uninhabitable place of bleakness.

Mercury orbits nearer the Sun than any other planet in our Solar System and, as such, experiences some of the highest surface temperatures of all the planets. Mercury circles the Sun every 88 days - faster than any other planet in the solar system - and one year on Mercury is shorter than three Earth months. Mercury is the innermost planet of the Solar System, taking only 88 Earth days to make one orbit around the Sun and ranging an average distance of about 58 million kilometers (36 million miles).

Mercury's orbit is tilted seven degrees from Earth's orbital plane (the ecliptic), the largest obliquity among all eight known Solar Planets. Mercury's orbital eccentricity is the largest among all known planets in the Solar System;[b] at perihelion, Mercury's distance from the Sun is only about two-thirds (or 66%) that of the distance at aphelion. Like Venus, Mercury orbits the Sun as a minor planet, inside the orbit of the Earth, with an apparent distance to the Sun never exceeding 28deg when viewed from Earth.

Using this definition of nearness over time--as noted above--it turns out Mercury is the closest planet to other planets in the Solar System. For instance, since Mercury is closer to the Sun than Venus, Mercury spends more time close to Earth; thus, Mercury can be the closest planet to Earth if averaged over time.

No, humans can not live on Mercury due to extreme temperature fluctuations, solar radiation, and a thin atmosphere.

Mercury achieves a poor conjunction -- a point at which it is closest to the Earth -- once every 116 days, significantly less frequently than either Venus or Mars. If we define a day as the time our Sun takes to return to a particular spot in the sky, a single day on Mercury is 176 Earth days.

Mercury's relatively short 88-day year means that completing just shy of 176 Earth days take it to go through one day-night cycle. Essentially, taking means a single day on Mercury is about the length of two of its years. At Mercury's present spin rate, one Mercuryian day-night cycle takes approximately 176 Earth days.

Despite this, humans can walk its surface because of its slower rotation, since turning once takes 59 Earth days. Despite being so close to the Sun, and the wild fluctuations of its extreme temperatures, humans, could technically walk on Mercury's surface.

What works against a sustainable life on Mercury is excessive radiation from the Sun, the extreme temperatures, and a lack of an adequate atmosphere. With Mercury's extreme temperature fluctuations, Mercury is probably not the type of planet humans will want to colonize. For life as we know it to exist, Mercury would have to be at temperatures that allowed liquid water to stay on its surface for extended periods.

Assuming that one can traverse a more temperature-stable region during the night-day cycle, one can survive for approximately two minutes on the surface of Mercury. While humans cannot survive in temperatures this cold for very long, you might be able to survive for much longer than on Venus or Mercury. Unlike Mercury, temperatures are pretty constant on Venus, regardless of daytime or nighttime, so you cannot escape the extreme heat.

Venus also has extreme temperatures, but it is not due to its closeness to the Sun; rather, it is the thick atmosphere that is responsible. Greenhouse gases in Mercury's atmosphere trap heat from the Sun, leading to temperatures exceeding 470 degrees Celsius, which is warmer than Venus.

Mercury's neighbor, Venus, has an atmosphere made mostly of thick carbon dioxide, which traps the sun's heat and causes the scorching surface temperatures to reach more than 470 degrees Celsius. Mercury's surface temperature hits a blistering 430 degrees Celsius[800 degrees Fahrenheit] in daylight, dropping sharply at night to -180 degrees Celsius[-290 F] without its atmosphere.

However, compared to the amount of radiation reaching Earth, seven times more sunlight is washed on Mercury's dayside, baking the planet's surface down to temperatures up to 430 degrees Celsius (800 degrees Fahrenheit). During daylight, Mercury's skies appear black rather than blue, as Mercurys have almost no atmosphere to diffuse sunlight. Without a thick atmosphere, for example, to diffuse the sun's incoming light, its daytime sky would look nearly entirely black, with stars that would never glitter.

Not only is the sunlight surrounding Mercury roughly 10 times as strong as that surrounding Earth, but Mercury's surface radiates heat back into space. Because of this, Mercury has no way of trapping the heat from our Sun and experiences extreme variations in temperature. Mercury does not have an atmosphere, as does Earth, which traps and holds heat, so the side facing away from the Sun is always extremely cold - particularly since it takes Mercury, which rotates slowly, approximately 59 Earth days to finish its orbit.

For instance, Mercury's slow spin period means one side of the planet faces our Sun for long periods, reaching temperatures up to 427degC (800degF), while the side facing away experiences extreme cold (193degC; -315degF).

Interestingly, the Sun follows a strange path across Mercury's sky during Mercury's daytime due to an interaction between Mercury's rotational velocity and its highly elliptical orbit around the Sun.

With little or no atmosphere to trap heat, Mercury has a diurnal temperature change greater than any other planet in the solar system, from about 100 K (-173degC; -280degF) at night to about 700 K (427degC; 800degF) in equatorial regions in the day. It does not shield the planet from harsh Sun radiation or radiation from space and does not store heat or provide a breathable atmosphere. Conditions on that world are tantamount to those of Mercury, where days are blazingly hot, nights are freezingly cold, and humans only last for about eight days.

We also know that there is water ice on Mercury today, located in the deepest Polar Craters, which are permanently shaded. We thus are far colder because there is no atmosphere distributing the heat of sunlit regions.

The exosphere gives Mercury little protection from objects such as asteroids, and Mercury is peppered with craters to the point where Mercury looks similar to the moons of Earth. Its closeness to the Sun means one side of the planet can reach blistering temperatures above 430 degrees Celsius. Still, Mercury orbits so slowly that the coolest side can plunge to below -180 degrees Celsius.

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Read More About Mercury:

Is There Life on Mercury?
No, life as we know it would not be able to survive on Mercury due to extreme temperature fluctuations, proximity to the Sun, and being void of an atmosphere.
Can we colonize Mercury instead of Mars?
Mercury’s extreme temperature fluctuations, solar radiation, and lack of an atmosphere would make it very difficult, if not impossible.

Read About The Possibilities of Living On Other Planets:

Can Europa sustain human life?
The chances for life there were always iffy, as a global ocean lay under a few miles of ice, which separated it from oxygen being produced on the surface.

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