How WEBB works
The telescope has some unique design features, like a segmented mirror and a huge sunshield
Externally, Webb looks very different from Hubble. The latter, just like a traditional telescope, is enclosed in a cylindrical tube that shields the optics from stray light. Depending on its position in its orbit, Hubble can be exposed to a lot of this – blazing sunshine from one direction, reflections from Earth’s surface in another and maybe even the Moon. But Webb is more fortunate. Seen from the L2 point, all these sources are in more or less the same direction, so all the telescope needs is a single large sunshield. The bare optics, in the form of primary and secondary mirrors, sit on top of this. The result, at first glance, looks more like a radio telescope than an optical one.