The Moon Hides a Scrambled Record of 100M Years of Supernovae. Researchers Just Unscrambled It.
A new study in the journal Physical Review Letters claims to have deciphered an almost unimaginably complex scrambling of Moon dust, allowing the researchers to look much further back into the history of stellar explosions than ever before.
Scientists have long known that layers of sediment at the bottom of the ocean can contain evidence of historical supernovae around the galaxy. It comes down to a number of marker substances, but most notably, the iron isotope 60-Fe.
60-Fe is produced almost exclusively in massive stars and their supernovae, and has no known way to form on Earth; if you find it here, it must have arrived from a supernova elsewhere.
The only problem is that the ocean floor has been mixed up by various events, especially back when it wasn’t ocean floor at all, which complicates the dating process. Since deeper samples aren’t always older samples, scientists also need a marker substance to date layers beneath the ocean floor.
In that context, they use the beryllium isotope 10-Be, which is created when cosmic rays interact with molecules in the upper atmosphere. Since it’s born as it is embedded in the soil, 10-Be provides a straightforward way to date sediment layers and, in doing so, the 60-Fe found at that same depth.
This figure shows different compositions for soil near different Apollo landing sites. The figure specifically maps the iron isotope Fe-60.
Credit: Costello et al, 2026
This allows scientists to infer a history of 60-Fe arrival going up to 10 million years back. On the Moon, however, evidence could be much more long-lasting and theoretically provide a history stretching as far back as ten times that.
However, the Moon has no pathway to create 10-Be for easy dating, and in any case, its surface is constantly bombarded by meteor impacts large and small. Not only is there little marker substance to use, but the layers have been mixed to a dizzying extent. This mixing process is called “impact gardening,” and it constantly churns up dust from lower, older layers so those layers can settle on top of younger layers, creating confusion.
To get past this, the researchers used a property called “regolith maturity” to quantify how long a particular sample had been exposed to the vacuum of space. While buried in lower layers, the regolith does not mature in this way. The researchers created an incredibly complex mathematical model that can use this data, and preexisting models for impact gardening, to map 60-Fe concentration onto a strict, linear timeline.
All this will only really become useful after programs like Artemis are completed and crewed missions return to Earth with additional samples from the Moon. Future astronauts will definitely be tasked with drilling lunar core samples, and it’s studies like this one that will let scientists make sense of those samples when they arrive.
