NASA's James Webb traced the history of two interacting dwarf galaxies 24 million light-years away

NASA's James Webb Space Telescope traced the history of two interacting dwarf galaxies, NGC 4490 and NGC 4485, about 24 million light-years away in the constellation Canes Venatici. The image was released on December 2, 2025, as Webb's Picture of the Month. Using Webb's NIRCam and MIRI instruments, researchers mapped where young, middle-aged, and old stars reside and traced the timeline of the encounter: the galaxies swept close to each other roughly 200 million years ago, then burst alight with new stars about 30 million years ago, with new clusters forming where their gas mixed. Because dwarf galaxies resemble the young galaxies of the early universe, encounters like this offer clues to how galaxies billions of years ago grew and evolved. Credit: ESA/Webb, NASA & CSA, A. Adamo (Stockholm University), G. Bortolini, and the FEAST JWST team; N. Bartmann (ESA/Webb)