An ultraviolet image composite of the hydrogen atoms surrounding comet 3I/ATLAS, the third interstellar object ever detected by astronomers, as it passes through our solar system. This image was taken on Sept 28, 2025- just days before the comet’s closest approach to Mars - by an instrument on NASA's MAVEN spacecraft, which has been studying Mars from orbit since 2014. The instrument, the Imaging Ultraviolet Spectrograph, takes pictures in the ultraviolet part of the spectrum to reveal the chemical composition of objects. The image shows hydrogen emitted from different sources: the comet (dim spot on the far left), hydrogen from Mars (bright emission on the right), and hydrogen flowing through our solar system between the planets (dim emission in the middle). MAVEN’s spectrograph distinguished the comet’s hydrogen from the interplanetary and Martian hydrogen using a special mode to separate each source by its speed. Hydrogen emission from the comet is confined to the location of the comet on the sky, which is why it is small and round instead of extended.