Pluto may not be a fully fledged planet, but at least it’s not the dwarfiest of dwarf planets. Its sibling, Eris, is not as large as astronomers thought, according to a new study. A rare stellar blockage event last year helped astronomers obtain some new measurements of the distant icy world, and they say it is quite dense and it may develop a feeble atmosphere as it moves closer to the sun.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.