How much mass does the Sun lose over its lifetime? (Thanks to Dan Fehlauer, Dexter Southfield HS, for suggesting the question.)
China is planning to launch an artificial moon to help illuminate a city at night. How big a satellite would be needed to provide as much illumination as a full moon?
Look for the answers online at tpt.aapt.org
Question suggestions are always welcome!
For more Fermi questions and answers, see Guesstimation 2.0: Solving Today’s Problems on the Back of a Napkin, by Lawrence Weinstein (Princeton University Press, 2012).