Makemake ( officially known as 136472 Makemake ) is a dwarf planet , discovered on 31 March 2005 by astronomers Michael E. Brown , Chad Trujillo and David Rabinowitz . Initially known as ' and later given the minor planet number 136472 , it was discovered on March 31 , 2005 , by a team led by Michael Brown , and announced on July 29 , 2005 . Its name derives from the Rapanui god Makemake .