How a Space Telescope Oriented Self Works

How does a space telescope oriented self know which way it's pointing? And also, how does it turn to point that something it wants to look at? I think we're asking both questions and have different answers, both of which are really fascinating. Do you probably find all NASA selling those selfie opportunities? Hubble is quite delicate and if too much light enters its aperture, it could damage it. They have to be very careful by not pointing it, for example, towards the sun.