I like the idea as well. Perhaps if there are enough of each of us with different levels of knowledge in the subject matter you could consider a "basic" astronomy course and an "advanced" astronomy course. Those of us with little math experience could certainly reap the benefits of a freshman course while those already deeper into the subject could be working at a junior level. You could just post the prerequisite skillset for each class and let us select which forum to subscribe to.

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I was just sitting here contemplating the immortal words of Socrates who said, "I drank what?"

"Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot." --Carl Sagan "Pale Blue Dot"