In July 2015 the New Horizons spacecraft flew by the dwarf planet Pluto, taking thousands of images and as many other scientific measurements over the course of a few weeks and days. Views both global and close-up revealed the nature…

A classic science fiction story (“Nightfall” by Isaac Asimov) was set on a planet in the midst of a globular cluster, its sky ablaze with six suns that prevent true night from ever falling. Once every 2000 years or so,…