Before you can peer back in time 13.2 billion years, your telescope needs to be calibrated correctly, so you can be sure objects in your mirror are really as bright (and therefore as distant) as they appear. Astronomers have a few tricks to help them do this, including using light bulbs and distant stars. Now one astronomer has a simple calibration solution: put a light bulb in space.
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.