Chris Hemsworth celebrated his younger brother and ex-husband of Miley Cyrus , Liam Hemsworth ’s birthday in an adorable way.A post shared by Liam Hemsworth (@liamhemsworth)The ‘Thor’ actor took to Instagram to wish his brother a happy 31st birthday Wednesday morning by posting an old throwback photo of the two. In the picture, the brothers are posing in matching yellow school uniforms.