Kenny Chaffin July 20, 2023 8:51am The Known Knowns, the Known Unknowns, and the Unknown Unknowns https://arstechnica.com/science/2023/07/new-slow-repeating-radio-source-we-have-no-idea-what-it-is/ #space #astrophysics Something in space has been lighting up every 20 minutes since 1988 We have no explanations for this sort of slow repeat.