SE Newsletter December 1998

General: Eclipses and standing up eggs

From: "Steven Van Impe" To: "SE" Subject: [SE] Eggs standing up?

Hello all, I was reading some reports about the Malaysian eclipse, and on the page of Olivier Staiger ( he tells about a local experiment: during the eclipse, it's easier to put an egg standing up because of the combined gravity. The pictures he adds tell everything. What I want to know is, has anybody else tried this? Can the same effect be reached during a new moon phase? Kind regards, Steven Van Impe

From: "Govert Schilling" To: Subject: RE: [SE] Eggs standing up?

This is pure nonsense, as a simple calculation will show. The tidal forces of the sun and the moon can only be 'felt' by large bodies, like the Earth's oceans and mountain ranges. An egg just doesn't respond to them, for the same reason that you'll never see low and high tide in a cup of tea (try it!). Sure, if sun and moon are in the same direction and overhead (meaning their gravity opposes the gravity of the earth), the weight of a body on Earth is slightly less than when the pair is underneath (when their gravity is in the same direction as Earth's), but again, the difference is so tiny that 'local' effects (like the exact position of an egg's yolk etc.) will overwhelm the effects of the sun and moon. Also, if someone tells you that there's a tidal or gravity effect at work during a solar eclipse, but not during a normal new moon, you ought to get suspicious...

Govert Schilling Dr. H.Th. s'Jacoblaan 36 3571 BM Utrecht The Netherlands t: +31 (0)30 273 02 29 m: +31 (0)655 87 72 87 f: +31 (0)30 272 34 03 e: [email protected]

From: [email protected] Subject: [SE] Eggs standing up? To: [email protected]

It is a joke that people stand up eggs during eclipses. The change in gravitational pull is negligible, and eggs stand up at other times just as well as they do during eclipses. So new moon, full moon, quarter moon, any other day, eclipses, no eclipses--it is just as easy or just as hard to stand up an egg.

When I crossed the equator with a planeload of scientists en route to the 1973 eclipse, the pilot waggled the wings to indicate the change in Coriolis force. We all thought it was very funny. And standing an egg on end during an eclipse is also supposed to be a funny thing for knowledgeable people. Jay Pasachoff Prof. of Astronomy, Williams College

From: Jean Marc Lariviere [email protected] To: [email protected]

Subject: Re: [SE] Eggs standing up?

When Olivier sent me his photographs of eggs standing up a few months ago I was both amused and intrigued. But a more elementary question arose. How easy was it to get eggs to stand up anyways? Olivier was quick to put my query to the test and the next day he e-mailed another photo of eggs standing up on his kitchen table in Geneva. As it turns out it's not at all difficult to get eggs to stand upright, it's just that one doesn't think of trying until some eclipse lore turns up. Jean Marc Lariviere

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