Galileo's discoveries and what determines a star's spectral class

[University]

Hello All,

I am studying for my introductory astronomy exam and I came about these two question;

Galileo discovered

a) radioactivity b) some moons of saturn c) 2 moon of Mars d) some moons of Jupiter e) the telescope

I know he discovered 4 moons of Jupiter but "some" is a bit tricky. He definitely discovered the telescope. Not sure which to choose

Also, The most important property of a star in determining its spectral class is

a) surface temp
b) mass
c) luminosity
d)composition
e) age

I think A

 

[qraal]

Some moons of Jupiter, definitely. He didn't invent the telescope, merely used it spectacularly.

 

[University]

Thanks