Even as a star dies, its light endures—echoing across the cosmos.⁣ ⁣ The James Webb Space Telescope is giving astronomers an unprecedented look at the fine details and 3D structure of the dust and gas between the stars.⁣ ⁣ The space between the stars is not empty, but rather filled with filaments of dust and gas (known as the interstellar medium), which is often invisible until something illuminates it.⁣ ⁣ Here, a long-ago supernova explosion, acting like a flashbulb, has heated some of this interstellar material, causing it to glow in the infrared, creating a thermal “light echo.”⁣ ⁣ As the supernova illumination travels through space at the speed of light, the echo appears to expand. Click the link in @NASAWebb’s bio to read more and to see more images and a video showing the change over time.⁣ ⁣ The structures in these filaments are on a remarkably small scale of about 400 astronomical units, or less than one-hundredth of a light-year. (An astronomical unit, or AU, is the avera...