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)
Monday, October 29, 2018
Concentric Ellipse
Today's Astronomy Picture of the Day shows PGC 42871, an elliptical galaxy in the constellation of Centaurus. The galaxy is surrounded by shells of stars (and globular clusters within the layers of shells). What is causing this?
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