FinePix E900: how to focus to infinity

[amo...@mclink.it]

I have a Fuji FinePix E900 digital camera. How do I focus it to
infinity in manual mode?

More specifically. I do know which controls I have to operate to change
focus. But given that focus feedback in manual mode is limited
(information on the display is scarce, and the image is not enlarged
while focusing), how can I be sure that I have correctly focused to
infinity?

I ask this question mostly in the context of astronomical photography,
e.g. imaging the Moon or a wide star field with the camera's zoom, or
the Moon and a landscape.

Paolo Amoroso