For a long time, the planet Mercury remained an enigma to scientists, as it is a planet that is known for its extremes, and now a new study has concluded that planets like Mercury, that are both dense and extremely iron-rich, are probably quite rare.
According to Phys.org, when it comes to extremes, there aren’t many planets that can beat Jupiter. For instance, the planet’s years are actually shorter than its days and one side of the planet is locked in severely freezing conditions while the opposite side is drenched in inferno-like heat from the sun, which are things that could hardly be contemplated here on Earth.
Even though Mercury is still a terrestrial planet that is similar in that respect at least to Venus, Mars and Earth, that is where the similarities end, as it contains more iron than any of these planets. It has been surmised that it is probable that at some point in its history, Mercury faced a huge impact which caused it to lose much of its rocky mantle.
But according to a new study that was recently published, scientists at the Center for Theoretical Astrophysics and Cosmology (CTAC) at the University of Zurich now believe that rather than just one extreme collision, it may be more likely that Mercury’s oddness is a result of many different collisions with objects in space.
Besides Mercury’s iron-rich core, scientists also now believe that its core may be considered to account for 42 percent of its total volume. This is in marked contrast to Earth, where its core is just 17 percent of its volume.
— Phys.org Space News (@physorg_space) September 6, 2018
In the new study, scientists examined two different possibilities that could account for Mercury’s iron core. The first is that Mercury may have had its strong iron core from its creation. As it is so near to the sun, its metals may have migrated inward with its rocky features moving in an outward direction.
The second possibility, and the one that appears most likely, is that evaporation or a major impact or multiple impacts caused Mercury to shed much of its rock. This theory is the one that is currently most accepted by scientists today.
“Our study isn’t the first one to propose giant impacts to explain Mercury’s large iron core, but confirms that we need rather specific conditions for giant impacts,” lead author Alice Chau explained. “It seems that forming Mercury is difficult. In another sense, this is reassuring because we do not observe a lot of exoplanets that are similar to Mercury in composition. Also, even if it is a rare event, only one impact is needed.”
While both theories are certainly plausible, both events are still extremely rare, and very few planets like Mercury have been found.
The new study which discusses why the extreme and iron-rich planet Mercury is such a rarity in the universe can be read at arXiv.org.