Translucent ‘glass globules’ found on the Moon – which isn’t as weird as you’d think
We're calling them moon marbles.
There are some strange things out there in space, but it turns out spheres of glass aren’t one of them.
Recent images sent back from the far side of the moon show two perfect balls of glass sitting there on the dusty surface.
The pictures were captured by the Chinese Yutu-2 mission and could give us important clues about the moon’s history.
Sadly, the Chinese space rover wasn’t able to get any compositional data on the glass balls – which we’re going to call moon marbles – yet, but they will likely be designated as research targets for the mission.
In actual fact, glass on the moon isn’t that weird a find.
All you need for glass to form is silicate material and very high temperatures – two things you can easily find on the moon.
Alternatively, if the glass didn’t form recently, it may have been left over from a volcanic period from the moon’s past or have been created from the intense heat generated by a meteor impact.
The only slightly odd thing about the glass balls discovered by Yutu-2 is the size. Previous sightings of glass on the moon have been tiny: usually less than a millimeter in size.
![Glass is ubiquitous in lunar regolith, and volcanism and hypervelocity impacts are the major mechanisms of forming lunar glasses. Volcanic glasses on the Moon occur as quenched skin of basaltic rocks or as glass spherules in pyroclastic deposits. Lunar volcanic glass spherules are less than 1 mm in diameters, and most are less than 300 ?m [1]. Impact glasses on the Moon are formed by cooling of impact melt and/or condensation of impact vapor, and impact glass spherules have rotational shapes, smooth surfaces, and largely clast-free interiors [2]. Recognized impact glass spherules on the Moon are dominantly sub-millimeter in sizes, and few are up to ?8 mm in diameter [3]. Glass spherules record important information about the mantle composition and the history of lunar volcanism and impact cratering [4]. Transparent and translucent glasses on the Moon are less than 1 mm in diameters, and larger ones are dark and opaque [5]. Hitherto discovered macro-sized glass globules on the Moon (up to ?4 cm in diameter) are opaque impact glass (Fig. 1a, b) that usually contains hollows and lithic clasts [6].](https://metro.co.uk/wp-content/uploads/2022/02/SEI_89605046.jpg?quality=90&strip=all&w=711)
But these translucent glass globules are much bigger: around 15 – 25mm across.
Although it does bear pointing out that astronauts from the Apollo 16 moon mission returned to Earth with moon marbles up to 40mm across.
Nevertheless, the Chinese team reckons the most likely explanation is the marbles formed from volcanic glass called anorthosite that melted again following a nearby impact from a meteor. This resulted in them re-forming into translucent round ‘globules’.
‘Collectively, the peculiar morphology, geometry, and local context of the glass globules are consistent with being anorthositic impact glasses,’ the researchers wrote in their study.
‘As the first discovery of macroscopic and translucent glass globules on the moon, this study predicts that such globules should be abundant across the lunar highland, providing promising sampling targets to reveal the early impact history of the moon,’ they said.
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