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.

Josh Habka

Dec 24, 2022

9 min read

home, Mercury, Astronomy 🔭, Solar System

Mercury - a planet without an atmosphere, with temperatures that reach as high as 800 degrees Fahrenheit (430 degrees Celsius) - might have once harbored chemical ingredients for life under its surface, according to research published last week in Scientific Reports. Although its temperatures now hover near 800 degrees Fahrenheit during the day and near minus 300 degrees at night, a new study suggests that the planet Mercury could once have supported life. Mercury's extremely varying temperatures make it unsuitable for life as we know it -- or for any form of life that exists on Earth, for that matter.

The vast differences in day-night temperatures make adapting to Mercury practically impossible for any living organism. Mercury's surface temperature hits a blistering 430 degC [800 degF] in the daytime, while, without its atmosphere, it plunges to -180 degC [-290 degF] in the evening. Given that its surface could endure temperatures as low as -330 degrees Fahrenheit and as high as 800 degrees Fahrenheit, it is obvious no living organisms would be able to survive there.

Volatiles like water might have provided a habitat suitable for life below ground - Mercury's chaotic surface is far too warm in itself, heating to about 800 degrees F in the afternoon. Although Mercury's daytime surface temperatures are typically extremely hot, observations strongly indicate ice (frozen water) exists on Mercury. We also know that water ice is still present today on Mercury, located in the deep Polar Craters, which are permanently shaded. We, thus, are significantly cooler because there is no atmosphere distributing the heat from sunlit regions.

The MESSENGER probe confirmed the existence of a few small ice deposits in a few of Mercury's craters, which are always shadowed by the sun. Water ice was found in Mercury's north pole, according to KJZZ, raising the possibility the life-sustaining compound was also present at one time on another part of the planet.

The ice is hidden deep within craters in its poles, where the sun never rose, and conditions were permanently dark and cold. As the closest planet to the sun -- without any real atmosphere -- Mercury is a scorching, uninhabitable hive of desolation. Because it is the closest planet to the sun, it is tempting to think it is the warmest planet too, but this is wrong.

Despite being closest to the sun, Mercury is not the hottest planet in our solar system -- that title belongs to neighboring Venus, thanks to its thick atmosphere. The smallest planet in our solar system and closest to our sun, Mercury is just slightly larger than the moon of Earth.

Although Mercury is the smallest planet in our solar system, Mercury has a crater the size of all of western Europe. Because Mercury is the fastest planet, with the least distance it has to traverse the sun, it has the shortest year of any planet in our Solar System at 88 days. Because Mercury's orbit is so short, it appears Mercury moves through the sky more quickly than the other planets.

For instance, although it is the closest planet to the sun, the daytime sky is still blazing black since it has no real atmosphere that spreads out the light. Because Mercury has an atmosphere, Mercury cannot hold on to any of the heat coming from the Sun, and as such, Mercury experiences some crazy temperature changes. As the closest planet to the sun, this chaos boasts extreme temperatures, unlike anything we would ever experience here on Earth.

Mercury boasts strong solar radiation and extremely long days but could harbor some form of life below the planet's surface. If this is correct, Mercury's chaotic terrain may have been able to harbor prebiotic chemical species -- perhaps forms of simple life -- under its surface at some point in that chaotic first few years. According to a new theory, Mercury's fractured, chaotic terrain could have been formed from volatiles - elements and compounds that could readily transition from a gas to a liquid or a solid - under its surface.

Keeping in mind the conservation of matter, researchers suggest in a new study that volatiles beneath the surface created those features rather than impacts and earthquakes. The planet's surface was caused not by the result of earthquakes but by volatiles, which can change the state of the elements quite rapidly, a new study says.

While an untimely asteroid visit has definitely altered its surface, data from one team shows that Mercury's outer layers continued to shift even several billion years after the space rock struck, reports Passant Raby for Inverse. Instead, it appears that the surface of the planet was still being formed as recently as 1.8 billion years ago - about two billion years after forming a massive impact basin. Mercury's surface environment has been justifiably excluded from scientific consideration as a possible habitat for life.

Mariner 10 in 1973 merely flew by Mercury, and the MESSENGER probe studied the planet from orbit for four years before being ordered to crash-land on its surface in 2015. The long path taken by the MESSENGER probe -- it reached Mercury's orbit nearly four years after departing -- was incredibly time-consuming.

Astronomers think that is because it is too small, so its gravity is weak, and therefore cannot grab onto a moon. Mercury cannot keep a moon in its position because of its small size, weak gravity, and proximity to the sun. Due to Mercury's oval-shaped, egg-shaped orbit and its slow spin, it appears that the Sun briefly rises, sets, and rises again from certain parts of the Mercury's surface.

The primary feature of Mercury contributing to temperature variation is the planet's atmosphere. Mercury also has lava flows, which may, in a certain way, contribute to the extreme temperatures on Mercury. For life as we know it to exist, Mercury must have temperatures allowing liquid water to stay on its surface for extended periods.

It does not shield Mercury from harsh Sun radiation or radiation from space, and it does not store heat or provide a breathable atmosphere. With little atmosphere to retain heat, its surface temperatures change diurnally more than any other planet in the Solar System, from about 100 K (173degC; -280degF) at night to about 700 K (427degC; 800degF) in the equatorial regions in the day. There is actually--I mean, that shocked me as I was reading those papers, that is 800 degrees at the surface, and yet you cannot have ice on the poles of the mercury.