The Richat Structure in the Sahara Desert of Mauritania is easily visible from space because it is nearly 50 kilometers across. Once thought to be an impact crater, the Richat Structure’s flat middle and lack of shock-altered rock indicates otherwise. The possibility that the Richat Structure was formed by a volcanic eruption also seems improbable because of the lack of a dome of igneous or volcanic rock. Rather, the layered sedimentary rock of the Richat structure is now thought by many to have been caused by uplifted rock sculpted by erosion.
On the dark and stormy night of September 12 at Hverir, a geothermal active area along the volcanic landscape in northeastern Iceland.
This is a true color composite of Saturn and Earth as seen by the Cassini spacecraft on July 19, 2013.
Many look upon the GF as evidence that we’ll destroy ourselves in the future. The basic idea is that every civilization destroys itself before developing space-faring technologies. Hence the empty cosmos. Given our own trajectory and the ominous presence of apocalyptic weapons, this scenario certainly seems plausible. We’re not even close to going interstellar, yet we’re certainly capable of self-annihilation.
But that doesn’t mean this interpretation of the GF is the correct one. Rather, it’s quite possible that human civilization has already passed the Great Filter. Should this be the case, it would be exceptionally good news. Assuming there’s no other filter awaiting us in the future, it means we might be the first and only intelligent civilization in the Milky Way.