a moon is a kind of celestial object / body & what is on the surface of the moon is a kind of detailed observation ->  what is on the surface of the moon is a kind of detailed observation of a celestial object  what is on the surface of the moon is a kind of detailed observation of a celestial object & detailed observation of celestial objects requires a telescope & a telescope is used for observing moons -> a telescope can be used to observe what is on the surface of the moon