Summer Science Experiment: Is It Really Hot Enough to Fry an Egg?

Photo:  Paolo Valdemarin /Creative Commons

Photo: Paolo Valdemarin/Creative Commons

How hot does it have to be to fry an egg on the sidewalk? Celebrate sidewalk egg frying day on July 4 by trying this simple experiment for yourself.


The Question: Is it hot enough to fry an egg on the sidewalk? 

What You Should Know: This expression has been in popular use since at least 1899, even though it’s surprisingly hard to actually cook an egg on a sidewalk. To become firm, an egg needs to cook at a temperature of at least 158° F — lower than that, and the proteins in the egg won’t coagulate properly. Sidewalks, even at their very hottest, don’t generally reach a temperature of more than 145° F. (And cracking the egg onto a sidewalk actually lowers its temperature a little more.)

Try This: Crack an egg onto a sidewalk, and see what happens. Chances are, it won’t cook—but maybe you can brainstorm ways to make your patch of sidewalk a little hotter. Try using mirrors, magnifying glasses, or aluminum foil to concentrate the heat and cook your egg. Still no luck? Since dark objects absorb more heat than lighter ones, see if your egg cooks any better on a blacktop. If your pavement doesn’t produce satisfactory eggs, see what happens when you try to fry an egg on the hood of a hot car—metal conducts heat better than pavement, and people have successfully whipped up sunnyside-up eggs a la hood. (Clean up right away, though, because the acid in egg yolks can damage your paint if you leave it sitting more than a few minutes.)

Keep in Mind: You don’t want to actually consume any of the eggs you use in this experiment, you shouldn’t do anything on anyone’s car without their permission, and you definitely want to clean up your mess afterwards.