More Treasures in Earth’s Attic

Did Earth hide some of its treasure on the Moon?

Last week I wrote about how the Moon—Earth’s attic—has uniquely preserved fossils of Earth’s first life in pristine form. I say uniquely because Earth’s geological activity has destroyed those fossils while other solar system sites, such as Mars and Venus, have received far too low a delivery of Earth soil (through meteoroid transfer) to reveal any fossils.

A paper has been published in Science Advances establishing that yet more scientific treasure from Earth has been preserved on the Moon’s surface for us to discover.¹ That treasure is hematite—a reddish-brown to black mineral that often comes in crystal form. Learning how hematite got to the Moon will help scientists know what Earth’s atmosphere has looked like over its history—a find that I believe will reveal a Creator’s guiding hand.

Hematite is an iron oxide mineral (with the formula Fe₂O₃) and a common oxidation product on Earth, where it is abundant on the surface. It is the main ore harvested from iron mines. Hematite’s abundance stems from the enormous quantity of oxygen in Earth’s atmosphere and the amount of iron in Earth’s crust.

Most of us were taught that the Moon has no atmosphere (gaseous envelope). It is true that the Moon’s gravity is too weak to retain light molecular weight gases and the Sun’s ultraviolet and X-ray radiation that falls on the lunar surface is too intense for the heavier molecular weight oxide gases to survive. However, the Moon does retain a very thin atmosphere of mostly argon gas and smaller amounts of xenon and radon gases. These gases are the end products of heavy radioisotopes’ decay. The gases are heavy enough for the Moon’s gravity to retain them and, being inert elements, they are immune to decomposition by solar radiation.

How Did Hematite Get to the Moon?
The lack of oxygen or oxides in the Moon’s atmosphere implies that any hematite on the lunar surface cannot be indigenous. It must have been deposited there from other solar system bodies.

In the Science Advances paper, a team of seven American planetary astronomers led by Shuai Li of the University of Hawaii analyzed the Moon Mineralogy Mapper data. They found that hematite is present at high latitudes on the Moon and mostly associated with east- and equator-facing sides of craters, mountains, and hills. Also, hematite is much more prevalent on the lunar hemisphere facing Earth than on the opposite hemisphere. The locations and quantity of hematite found on the Moon imply that oxygen delivered from Earth’s atmosphere is the major oxidant that forms hematite on the Moon.

Lunar hematite presents physicists and chemists interested in a detailed history of the composition of Earth’s atmosphere with an exciting opportunity. In my book Improbable Planet I presented the best available data on the composition history of Earth’s atmosphere.² However, with respect to oxygen there are long stretches of time, particularly during the boring billion, where there’s great uncertainty on the amount and variability of oxygen content in Earth’s atmosphere.

Treasure-Hunting Implications
Planetary scientists can send spacecraft to hematite-rich regions of the Moon to bring back samples for analysis. Oxygen isotope and age-dating measurements in those samples will, for the first time, provide atmospheric physicists and chemists with an accurate history of the oxygen content in Earth’s atmosphere throughout the entire 3.8-billion-year history of life on our planet.

As I described in Improbable Planet and in a previous article, what we already know about the oxygen history of Earth’s atmosphere has affirmed God’s miraculous hand in shaping the physical, chemical, and biological history of Earth in preparation for human beings and civilization. I am persuaded that an accurate, detailed oxygen history of Earth’s atmosphere will yield even more evidence for God’s miraculous handiwork. Let’s retrieve the hematite treasure from Earth’s attic!