Four Years of Backyard Worlds: Planet 9

Since 2016, the Backyard Worlds: Planet 9 citizen science project (backyardworlds.org) has scoured the data from NASA’s WISE mission seeking new cold objects in the solar neighborhood. With help from more than 150,000 volunteers, the project has uncovered nearly 1800 objects of interest. These objects have fed a major follow-up observing program via Hubble, Spitzer, Keck, Magellan, Gemini, IRTF. APO, Lick and other observatories, filling in gaps in the known populations of late-T and Y brown dwarfs. I'll give an overview of the project and a progress report, highlighting some of the project’s recent discoveries: five “Y” dwarfs, the “missing link” brown dwarf, record-setting brown dwarf pairs and brown dwarf-white dwarf pairs, the oldest white dwarf with a disk, and the first extreme T subdwarfs.