Exoplanet Census Suggests Earth is (may be) Special After All

Astrogeology, Asteroids, Robots, Space Flight & Extraterrestrial Matters

Date posted: 02/24/16

Shannon Hall opines in Scientific American that more than 400 years ago Renaissance scientist Nicolaus Copernicus reduced us to near nothingness by showing that our planet is not the center of the solar system. With every subsequent scientific revolution, most other privileged positions in the universe humans might have held dear have been further degraded, revealing the cold truth that our species is the smallest of specks on a speck of a planet, cosmologically speaking. A new calculation of exoplanets suggests that Earth is just one out of a likely 700 million trillion terrestrial planets in the entire observable universe. But the average age of these planets, well above Earth age, and their typical locations, in galaxies vastly unlike the Milky Way, just might turn the Copernican principle on its head. Astronomer Erik Zackrisson from Uppsala University and his colleagues created a cosmic compendium of all the terrestrial exoplanets likely to exist throughout the observable universe, based on the rocky worlds astronomers have found so far. In a powerful computer simulation, they first created their own mini universe containing models of the earliest galaxies. Then they unleashed the laws of physics as close as scientists understand them that describe how galaxies grow, how stars evolve and how planets come to be. Finally, they fast-forwarded through 13.8 billion years of cosmic history. Their results, to be published in The Astrophysical Journal...pre-print: http://arxiv.org/pdf/1602.00690v1.pdf provide a tantalizing trove of probable exoplanet statistics that helps astronomers understand our place in the universe. Seems this implies a mild violation of the Copernican /mediocrity principle, which seems to be further augmented when supernova sterilization in different types of galaxies is taken into account. They speculate that some hitherto unrecognized mechanism related to the habitability of spheroidal systems may explain this anomaly, called Earth.