Thus , a very rough estimate from these numbers would suggest there are around one sextillion ( 1021 ) stars in the observable universe ; though a 2003 study by Australian National University astronomers resulted in a figure of 70 sextillion ( 7 x 1022 ) . Thus , a very rough estimate from these numbers would suggest there are around one sextillion ( 1021 ) stars in the observable universe ; though a 2010 study by astronomers resulted in a figure of 300 sextillion ( 3 ) .