The Summer of Hope digital-fundraising campaign only kicked off yesterday, but it’s already swept up some of the biggest names in music on behalf of research for cancer, diabetes and HIV/AIDS. Spearheaded by CAA‘s Rob Light, the #SUMMEROFHOPE effort has enlisted Facebook, Twitter and other participation from Britney Spears, PSY, One Direction, Adam Levine, Christina Aguilera, Pitbull, Selena Gomez, Gavin Rossdale, Usher, Matchbox Twenty, Thirty Seconds to Mars, Nicole Scherzinger, David Guetta and many more, for more than 126 million potential impressions. Watch for the hashtag and share it widely—this is an opportunity for a huge impact in a short time span.