Andrew P. V. Siemion

In October 2017, the Pan-STARRS telescope in Hawaii spotted an object moving too fast to belong to the solar system. It was 1I/ʻOumuamua, the first interstellar visitor ever recorded by astronomers. Since then, two more have joined it: comet 2I/Borisov and object 3I/ATLAS.

The Moon is a natural archive that has been collecting cosmic dust for billions of years. Among the microscopic grains that arrived from distant stars, there could be techno-specks — particles created by alien civilizations.