In the dictionary, we get Friday before Thursday. Since, in the dictionary all the words are in alphabetical order, and according to it F comes first than T.
Astronomy is the study of planets and heavenly bodies. Historically, astronomy has focused on observations of heavenly bodies. It is a close cousin to astrophysics. Succinctly put, astrophysics involves the study of the physics of astronomy and concentrates on the behavior, properties and motion of objects out there.