Conversation so far:
What is 39 from A Night at the Opera by the band Queen?
'39 was May's attempt to do sci-fi skiffle. The tale of a group of space explorers who embark on what is, from their perspective, a year-long voyage.
Who sings the song '39' by the band Queen?
Brian May sings the song on the album, with backing vocals by Freddie Mercury and Roger Taylor. During live performances, Mercury sang the lead vocal.
What do the space explorers realize when they come back from their voyage in the song '39' by the band Queen?
The space explorers realise that a hundred years have passed, because of the time dilation effect, and the loved ones they left behind are now all dead or aged.
Is there anything significant about the band Queen's A Night at the Opera album name?
The A Night at the Opera album title was inspired by the Marx Brothers film of the same name, which the band had watched during recording sessions.
Was 39 ever performed by anyone other than the band Queen?
George Michael performed '39 at the Freddie Mercury Tribute Concert on 20 April 1992.

Question: When did George Michael perform it?
Self-contained rewrite: When did George Michael perform the song '39'?