For nearly a century, scientists have been puzzled by dark patches in Venus’s clouds that appear in ultraviolet images but not in ordinary visible light. The pale yellow clouds themselves are well known, but the material responsible for the dark ultraviolet patterns has remained unidentified.
New calculations now put a firmer constraint on that mystery. By modeling how much light the unidentified material must absorb to produce the observed patterns, researchers have sharply narrowed the range of possible candidates. Any proposed substance must match that absorption strength to be plausible.
The results won’t solve the puzzle alone, but they give future spacecraft a clearer target. Instruments sent to Venus could use these absorption limits to test specific materials, potentially ending a mystery that has lasted more than a hundred years.