Fine. I’ll whisper it to you. The answer is Callisto.
If you look at the coloured orbs on the globe, you see green, red, yellow and blue (notice how they correspond with the colours of the houses? I bet you didn’t). The numbers on the note have the same colours. So you’re left with 4821. On the telescope it says K.M. which in this case means Kilometers, so you’re left with 4821 km. If you search for ’Jupiter’s moons 4821 km’ you’ll see that Callisto’s diameter is 4821 km.