The Infernal Equinox Egg Effect
06-Feb-2007
I was just reminded about this yet again by a
schoolteacher I met on the bus. My 4th grade teacher
managed to get my scientist Dad's hackles up
periodically from misinformation she taught us in her
science class. It was mostly little things, like when
I answered a class question that a "lightyear" is a
unit of distance, and she wrongly insisted it's a
unit of time. But the thing that really pushed Dad
over the edge was when we received a new issue of our
Weekly Reader one spring day, and in the science
section was a blurb telling us about the Equinox Egg
Effect. You may have heard of this myth, it’s a
strange one that has snuck into all sorts of funny
places to be described as a scientific fact. Well, so
our teacher thought this would make a neat class
project.
The Equinox Egg Effect myth says that at the exact moment of the vernal equinox in the spring, you can balance an egg perfectly on its end without it falling over. The vernal equinox is the time of year when the tilted axis of Earth’s rotation is facing 90 degrees away from the Sun. Equinoxes happen twice a year actually, the other time being the autumnal equinox. The equinoxes fall halfway between the summer and winter solstices, which are the dates when the Earth’s tilted axis points directly toward or away from the Sun. In the US is the solstices and equinoxes are chosen as the beginnings of the seasons, but that’s only a matter of convention. Perhaps the most familiar example to us of a different convention is the “midsummer’s night” of Shakespearean fame, which was another name for the summer solstice. There’s nothing particularly scientifically interesting about these dates, outside of the fact that at that time the days and nights are equally 12 hours long. Anyway, popular explanations as to why an egg should stand on its end at the exact moment of the vernal equinox are usually very vague, and generally cite something about gravity from the Sun being somehow momentarily stronger or more directed during the equinox. The Earth’s orbit about the Sun is in fact an ellipse, so that at one time of year called “perihelion” the Earth is closest to the Sun and another time of year called “aphelion” it is farthest. But the perihelion is not at the same time as the equinox, and while minor tidal differences are noticeable between perihelion and aphelion – the difference in closeness to the Sun does make for a slight difference in the gravitational pull of the Sun – there’s no reason that this different gravitational pull would make an egg stand up on your table. In addition, the equinox egg effect is generally only suggested to happen at the vernal equinox, and the autumnal equinox is never mentioned in spite of its exactly analogous orbital arrangement.
So we all had our eggs at our desks on the day of the equinox, and we were counting down to the exact equinox time, and we were having all sorts of fun trying to balance the eggs (and spin them, and playing catch with them, and… ). No one seemed to have any real luck with the balancing except my deskmate Lisa, who showed me this cool trick in which you can put a little bit of dirt on the table and set the egg on that to prop it up, and then gently blow away the rest of the dirt so you can pretend like you balanced the egg on its own.
When my dad came home from work that afternoon I showed him my Weekly Reader, and told him about the egg, and he totally blew his stack. He made me come upstairs to sit with him while he made a phone call to the Weekly Reader people to rip them a new one about feeding science misinformation to children. And I had to sit on a chair and listen to the whole thing. I couldn’t hear their end of the phone call, but from dad’s end you could pretty much figure it out. “Yeah, I want to talk to the moron who wrote this crap about balancing an egg on the equinox in my son’s Weekly Reader,” “Okay, you’re the science editor? What’s the hell’s the idea of putting this bulls**t in a science column?” “What? Of course it can’t happen. Aren't you the science editor?” “Look, a negligible gravitational difference isn’t going to change the egg’s balance” “What? No, I don’t care what direction the Earth is pointing.” “Don’t you know any basic physics? Dammit, what’s your degree in, puppetry?” Dad obviously wasn’t getting anywhere, and this was sure painful to listen to. I tried to get off my chair and sneak out. “Sit down!” he blared at me. The call went on for what must have been 10 or 15 more minutes until Dad finally slammed the phone down and furiously seethed, “Amateurs!” I wasn’t sure what that meant but it sure sounded like a bad word.
As we walked back downstairs, I asked him, “Dad? What’s that bad word you said? Does ‘amateurs’ mean sortof the same thing as ‘bulls**t’?” For reasons that weren’t clear to me at the time, Dad’s mood changed immediately and he about fell down the stairs he was laughing so hard. “Sometimes, son, sometimes.”
The Equinox Egg Effect myth says that at the exact moment of the vernal equinox in the spring, you can balance an egg perfectly on its end without it falling over. The vernal equinox is the time of year when the tilted axis of Earth’s rotation is facing 90 degrees away from the Sun. Equinoxes happen twice a year actually, the other time being the autumnal equinox. The equinoxes fall halfway between the summer and winter solstices, which are the dates when the Earth’s tilted axis points directly toward or away from the Sun. In the US is the solstices and equinoxes are chosen as the beginnings of the seasons, but that’s only a matter of convention. Perhaps the most familiar example to us of a different convention is the “midsummer’s night” of Shakespearean fame, which was another name for the summer solstice. There’s nothing particularly scientifically interesting about these dates, outside of the fact that at that time the days and nights are equally 12 hours long. Anyway, popular explanations as to why an egg should stand on its end at the exact moment of the vernal equinox are usually very vague, and generally cite something about gravity from the Sun being somehow momentarily stronger or more directed during the equinox. The Earth’s orbit about the Sun is in fact an ellipse, so that at one time of year called “perihelion” the Earth is closest to the Sun and another time of year called “aphelion” it is farthest. But the perihelion is not at the same time as the equinox, and while minor tidal differences are noticeable between perihelion and aphelion – the difference in closeness to the Sun does make for a slight difference in the gravitational pull of the Sun – there’s no reason that this different gravitational pull would make an egg stand up on your table. In addition, the equinox egg effect is generally only suggested to happen at the vernal equinox, and the autumnal equinox is never mentioned in spite of its exactly analogous orbital arrangement.
So we all had our eggs at our desks on the day of the equinox, and we were counting down to the exact equinox time, and we were having all sorts of fun trying to balance the eggs (and spin them, and playing catch with them, and… ). No one seemed to have any real luck with the balancing except my deskmate Lisa, who showed me this cool trick in which you can put a little bit of dirt on the table and set the egg on that to prop it up, and then gently blow away the rest of the dirt so you can pretend like you balanced the egg on its own.
When my dad came home from work that afternoon I showed him my Weekly Reader, and told him about the egg, and he totally blew his stack. He made me come upstairs to sit with him while he made a phone call to the Weekly Reader people to rip them a new one about feeding science misinformation to children. And I had to sit on a chair and listen to the whole thing. I couldn’t hear their end of the phone call, but from dad’s end you could pretty much figure it out. “Yeah, I want to talk to the moron who wrote this crap about balancing an egg on the equinox in my son’s Weekly Reader,” “Okay, you’re the science editor? What’s the hell’s the idea of putting this bulls**t in a science column?” “What? Of course it can’t happen. Aren't you the science editor?” “Look, a negligible gravitational difference isn’t going to change the egg’s balance” “What? No, I don’t care what direction the Earth is pointing.” “Don’t you know any basic physics? Dammit, what’s your degree in, puppetry?” Dad obviously wasn’t getting anywhere, and this was sure painful to listen to. I tried to get off my chair and sneak out. “Sit down!” he blared at me. The call went on for what must have been 10 or 15 more minutes until Dad finally slammed the phone down and furiously seethed, “Amateurs!” I wasn’t sure what that meant but it sure sounded like a bad word.
As we walked back downstairs, I asked him, “Dad? What’s that bad word you said? Does ‘amateurs’ mean sortof the same thing as ‘bulls**t’?” For reasons that weren’t clear to me at the time, Dad’s mood changed immediately and he about fell down the stairs he was laughing so hard. “Sometimes, son, sometimes.”