A Cold Clue in the Sky: Using Infrared Light to Hunt for Planet Nine
Chen et al. searched AKARI infrared data for Planet Nine by looking for heat rather than sunlight. After filtering millions of sources for movement and known objects, they identified two promising candidates. These objects matched expected brightness and motion patterns, but further observations are needed to confirm if either one is truly Planet Nine.
Hunting Planet Nine: A Far-Infrared Search with IRAS and AKARI
Terry Long Phan and collaborators searched for Planet Nine using infrared data from the IRAS and AKARI missions. They identified one strong candidate that appears to move across the sky over 23 years. However, more observations, such as with the DECam, are needed to confirm if it is truly Planet Nine.