What the Webb telescope was built to see, and why its first images were hard to read

The James Webb Space Telescope was designed to pick up faint light from the first billion years after the Big Bang — a chaotic stretch of time when vast swaths of hydrogen and helium gas gathered into the chains of galaxies we see today. Quanta Magazine describes the target plainly: not individual stars or nearby planets, but radiation that has been travelling since that early, gas-rich era. Even in the telescope's first images, astronomers could see what Quanta calls a whole zoo of mysterious smears of light. Building an instrument sensitive enough to catch those photons and knowing what you are looking at are two different problems; the second one is where the arguing happens.