These great hollow globes of artificial super-metals, and artificial transparent adamant, ranged in size from the earliest and smallest structures, which were no bigger than a very small asteroid, to spheres considerably larger than the Earth. (Olaf Stapledon, STAR MAKER)
Wednesday, July 9, 2014
Today's Astronomy Picture of the Day shows an artist depiction of the closest possible (again: possible) habitable extrasolar planet (found to date). Not quite a identical twin!