Unearthing Phenomenon's

Sometimes, when gazing at the moon, I wish I could throw a lasso around it and pull it a bit closer. Fortunately, for everyone on Earth, no one has crafted a lasso that's 384,000 km long - that is the approximate distance from the Moon. Aside from gravity and occasional lunar eclipses, it's challenging to imagine Earth having any influence on its distant partner. Surprisingly, though, the Earth is opening the door for chemical reactions to take place on the lunar surface, causing the Moon to rust.

Rust On the Moon Surface

When referring to rust here, it's not the flaky red substance found on an old car; instead, it's a type of iron oxide mineral known as hematite. This mineral was discovered on the Moon in 2020, encouraging a significant interest. Hematite typically forms when metallic iron comes into contact with liquid water and oxygen gas, both of which are scarce on the Moon. Despite the Moon's age of over 4 billion years, scientists had not yet found definitive presence of oxidized iron in the moon rocks when comparing evidence brought back by the Apollo program.

Oxidation is a reversible process; oxidized atoms can regain electrons through reduction reactions. In this case, a continuous stream of charged particles from the sun, known as the solar wind, acts as a powerful reducer. When protons in the solar wind hit hematite on the Moon, they induce reduction reactions which destroy the crystals, undoing any rust formation.

Earth's Contribution

On Earth, we are protected due to our strong magnetic field and oxygen-rich atmosphere which, in turn, promotes the easy formation and persistence of rust. However, the Moon lacks these conditions, and the solar wind continually undoes any rust that might form. So, where does the lunar rust come from? The answer lies in us - Earth.

Despite the Moon's lack of essential ingredients for rust formation, Earth reaches out through space and provides a source of oxygen and a temporary refuge for the buildup of hematite. Earth's magnetic field is not a perfect sphere, but instead, stretches into a cone shape every time earth wind runs into it, creating a long Magneto tail which extends to the Moon. During approximately five days each month, as the Moon passes through this tail, it is shielded from the solar wind while being blasted by charged particles from Earth's upper atmosphere. This phenomenon, which we colloquially know as "Earth Wind," contributes to the formation of rust on the Moon, just one element standing between it becoming a cool band name, back in 2017!

A study published in Nature Astronomy revealed that tens of thousands of Earth-originating oxygen ions are implanted into the moon every second. The researchers suggest that by digging into the lunar surface, we could even potentially get insights into Earth's ancient atmosphere based on the quantity and type of oxygen found. While this provides a source of oxygen, the story doesn't end there - water formation on the moon is also affected.

When solar wind protons collide with the right kind of molecule, they can react to create H2O. However, a study in 2023, suggests that there is no decrease in water formation rates when the moon is within Earth's Magneto tail, shielding it from the solar wind. This led the researchers, some of whom were involved in the 2020 hematite discovery, to hypothesize that Earth is not only involuntarily supplying oxygen ions to facilitate lunar rusting but also sweeping along electrons. When these electrons strike lunar soil, they trigger chemical reactions that generate water. In due course, this water can react with iron to produce hematite.

Despite the Earth and the moon being in a long-distance relationship, the sun plays a crucial role by assisting in the delivery of atom-sized "gifts". The solar wind causes the Earth to send over oxygen ions and electrons, leading to the formation of both rust and water on the moon. It's a cosmic interaction that adds a touch of sweetness to the celestial relationship, even for someone whose knowledge of chemistry might be a bit "rusty."