There is no comet
it is an angel sitting on a rock.
This is what I googled out: the name of the mural is "Anděl a Komediant" - "An Angel and a Comedian", painted in 1993 by Milivoj Husák. The tower belongs to the theater "Divadlo Na Provázku".
EDIT: "Na Provázku" means "on a rope" so the mural is probably a word play with the theater name.