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)
Thursday, March 5, 2015
The Iron Planet
Today's Astronomy Picture of the Day is an image taken by a (very much) overlooked mission: NASA's Mercury MESSENGER sent back this enhanced mosaic that points out the geological details of the Caloris basin.