A Difficult Place to Live There is no indication of life on Mercury. Temperatures during the day can reach 430 degrees Celsius (800 degrees Fahrenheit) while at night can dip to -180 degrees Celsius (-290 degrees Fahrenheit). Life (as we know it) is unlikely to exist on this planet.
However, there is some evidence that liquid water may have once covered much of the planet. If this is true, then perhaps life could again evolve on Mercury after all this time.
Our knowledge of Mercury's past and present comes from space-based telescopes such as those used by NASA's Mariner 10 mission in 1974-75. These instruments have revealed many surprises about this planet. For example:
Visible light images from Mariner 10 showed that the majority of the surface is made up of smooth spheres called maria (a term derived from Mercury). Spikes or ridges only cover about 15 percent of the surface. Scientists think that most of these features are caused by lava flows or geysers from deep within the planet's interior.
The image below was taken by Mariner 10's magnetic sensor. It shows a large dome called Caloris Basin to the east of the equator. This area is one of the few regions on Mercury where you might be able to see traces of life with your own eyes!
Plants require consistent temperatures. Mercury's temperatures range from 400 degrees Celsius during the day to -200 degrees Celsius at night. Any vegetation, living or dead, on its surface would either freeze or catch fire. That's a resounding no.
Mercury is uninhabitable because it lacks an atmosphere and has temperatures ranging from 212 to 1,292 degrees Fahrenheit (100 to 700 degrees Celsius). It is also highly toxic. Humans can survive on Mercury for a few days but then begin to suffer serious health problems including neurological damage and cancer.
The planet's name comes from the Roman god of commerce, and like Venus, Jupiter, and Neptune, it is a gas giant located within our solar system. However, whereas these other planets are mostly rock and ice, Mercury is almost all metal.
Its surface is covered by a thin veneer of soil, known as regolith, which builds up over time through meteorite impacts. This layer is only a few inches deep at most places, so most of the planet is made of metal.
However, because of its proximity to the Sun, most of Mercury is always under a cloud cover of some sort for part of the year. The sunnier parts of the planet may see clouds break down occasionally, allowing sunlight to strike the ground, but otherwise this world is always dark. During these periods when the sun is shining, temperatures often reach 450 degrees Fahrenheit (232 degrees Celsius), but when clouds return things cool down dramatically.
Mercury is not an easy planet to thrive on, but it is not impossible. It's worth mentioning that without a space suit, you wouldn't last long owing to a lack of atmosphere. Furthermore, Mercury experiences one of the biggest temperature variations in the solar system. From -300 degrees Celsius at night to more than 300 degrees during the day. This makes life very difficult for organisms that cannot adapt themselves well to changeable conditions.
However, humans have developed ways to adapt to such conditions. For example, they can produce heat-resistant proteins in their bodies called "mercuries". These proteins are also useful for preventing other elements such as iron from entering their body through their digestive systems. Humans can also absorb mercury through their skin or via the food chain. This is why it is important to avoid contact with any kind of metal inside Mercury's orbit. Otherwise, you might end up with a lot of mercury in your body.
The only thing you need to worry about is if you consume enough mercury to be harmful to yourself. The amount of mercury that reaches the human brain is still unclear, but there are measures you can take to lower the amount of mercury you ingest. For example, you should avoid eating fish eggs because they usually contain more mercury than other fish. You should also avoid consuming large amounts of seafood because some studies show that this increases the amount of mercury in your body.
The conditions on Mercury would make life difficult. See how in this infographic from Space.com. (Image courtesy of Infographics Artist Karl Tate) Mercury's MESSENGER pictures suggest that the planet possesses water ice at its poles, which are permanently black. The surface is also extremely hot because it is so close to the sun. All these factors combine to make life very hard for any species that evolves there.
Mercury is the smallest of the planets outside the Earth's moon. It has a diameter about 24% that of Earth's and orbits our star every 87 days. The reason it is not completely destroyed by radiation is because it is protected by its distance from the Sun. It takes the Sun's heat only as far as about 55 degrees away from the Sun before it becomes too cold.
Besides being small and distant from the Sun, another factor contributing to Mercury's extreme environment is that it rotates almost entirely around its axis in 88 days. This means that all of Mercury faces the same direction - away from the Sun - during most of its orbit.
As you might have guessed from its name, Mercury is very different from Earth and other planets in the solar system. It has very thin air that is made up of over 95% hydrogen and helium with only 4% oxygen. That's why scientists think that life as we know it could never develop on Mercury.