What Color Is Mercury?

Graphite causes Mercury to appear gray.

In the solar system, Mercury is the smallest as well the closest planet to the sun. The planet is quite different from the others in the solar system in a number of ways. An example of its difference is the color, which is just pure gray. This color is in stack difference to other colorful planets such as Venus, which is pale yellow, or Mars, which is reddish brown. Over the years, scientists had been puzzling over the color of Mercury until recent studies shed some light on the matter.

Formation of Mercury

Previously, scientists theorized that the gray color comes from the melting and hardening of molten materials when the solar system was formed eons ago. The hardened molten surface has stayed unchanged over the years since the formation of the planet. The few changes that have been experienced over the years have mostly come from the few meteors that collide with the planet. Scientists state that it is likely there are no volcanoes or similar erosive processes that may alter the structure of the planet. This consistency would likely explain the constant gray color.

Composition of Mercury

Prior to more recent data, some experts had theorized that the gray sections were a result of massive amounts of iron. However, the recent space mission by NASA clearly showed that Mercury has very little iron on the surface. Therefore, iron was promptly ruled out.


A study by NASA was conducted by the MESSENGER spacecraft that orbited the planet for four years. In the last months of its orbit, NASA brought it much closer to Mercury and eventually allowed it to crash. As it got closer to the surface, it was able to provide invaluable data about the planet’s surface. According to experts at NASA, that final dive was actually the most enlightening period as it confirmed the presence of graphite. The graphite is similar to the one used in making a pencil. The experts from NASA have not been able to ascertain for sure where the graphite originates from. However, they have theorized that the graphite is buried beneath the surface of the planet. The exposure happens when a meteor collides with Mercury, which then causes patches of dark gray to appear.

NASA approximates that the carbon material has been there since Mercury was formed or when it was in its infancy. During that time, the planet’s surface was made up of an ocean of magma. These carbon materials likely came to the top of the ocean where they solidified. The solid carbon material was then covered by lava from volcanoes of that time. The data from the study seems to corroborate this theory since all the dark patches were detected in craters, which means that some of the top surfaces had been scraped away.


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