'everything is just a total guess'? yeah .. scientists don't actually observe and measure things.. they just smoke weed and babble out random theories..
Not a website, but I would suggest starting "The Universe". It is on youtube. It will give you the basics of a range of things, and is broken down in a way the general population can understand.
The telescope 'collects' light on censors and then obtains an intensity in that area of the sky. Intensity does not have a colour (e.g., what colour is 52? 2? 99?) and therefore, the...