Gold and Red in a Webb Image of NGC 7129 Are Two Different Kinds of Hydrogen

NASA reports that the James Webb Space Telescope has revealed many protostars and stars within the glowing gases of NGC 7129. What makes the picture worth more than a glance is what its colors encode: hot, atomic hydrogen is shown in the golden region, while cooler, molecular hydrogen — gas shocked by the embedded protostars — is represented in red.

That second assignment is the informative one. The red marks gas that has been disturbed by the young stars sitting inside it, so the image reads less as a portrait of a nebula than as a map of where star formation is actively rearranging its own material. The gold is the hotter atomic gas; the red is the shock zone.