Hi, I'm the OP. I realized I was reading my own FML and thus created this account. To elaborate the story, these estimations are called Fermi problems and they're designed to teach dimensional analysis and approximation. They're typical in physics and engineering education and mine is a mix of both. The gerbil-sun is actually an approximation presented by Dr. Larry Weinstein - a physics professor and co-author of 'Guesstimation: Solving the World's Problem's on the Back of a Cocktail Napkin'. I believe the title should speak for itself... *sigh*... and that is exactly how it felt to be on the lecture. It is not that I think that learning to approximate is something to be scoffed at, per se. Indeed, it is skill that all experimental scientists and other people alike do need and find useful - often in basic, everyday life. However this was the third lecture in the series and they all have gone more or less within the realm of vagueness, "hip" examples and little to grasp for the inevitable physics homework that doesn't solve itself. On a related note, my lecture-mates also eagerly discussed the approximate number of piano tuners in Finland (in the original problem the place is Chicago) and at which height Felix Baumgartner might have broken the sound barrier during his sky-dive from the altitude of 39 kilometers (estimate). As this endless drone went on and on, I sat there, bored out of my mind, desperately wondering if and when the tune of the lecture(s) would change and how the heck would I utilize this in the homework, most of which requires some actual and exact calculation, not just some half-baked estimates. Thus the FML. P.S. There's actually a short article in thepointnews.com about Weinstein and his gerbil-sun, and I must say it was way more interesting (not to mention less time-consuming) a read than listening my class drone on and on about it and the other Fermi problems for 90 minutes straight.