Free Astronomy Magazine March-April 2024

9 MARCH-APRIL 2024 ASTRO PUBLISHING T he largest architectural structures of antiquity could be the first terrestrial technosignatures visible to a civilization a few thou- sand light-years away, capable of building telescopes and interfer- ometric systems currently beyond our reach. This is what Zaza Osmanov claims, in an article just published in Acta Astronautica . The image in the background gives an idea of how a civilization up to 4000 light years away might see the pyramids of Giza “today”.