Wednesday, March 20, 2013

First Day of Spring




Yay! it is the first day of spring!


Today, March 20th, at 11:02 UTC (7:02 am EDT) the center of the sun will cross directly over the equator, heading from south to north. This event is known as the March or vernal equinox. An equinox happens twice a year, usually on or around March 20 (vernal) and September 22 (autumnal).
 
The Latin word equinox means “equal night.” On the day of an equinox, daytime and nighttime are almost the exact same length. This will happen again on the autumnal equinox in exactly one half year.


People have always been fascinated by the equinoxes and there has been some interesting lore attached to it over the years. I remember when I was little my mom and I got up at the precise time of the spring equinox to balance an egg. I don't think we succeeded and ended up balancing nickles to make ourselves feel better, but it was a lot of fun. I have also read that people do the same thing with broomsticks. 


The theory is that gravity is 'balanced' when the Sun is over the Earth's equator; alternatively, the Sun exerts significantly greater gravitational attraction on the Earth during the equinoxes. 

Of course this theory brings up some troubling questions:

If it has to do with the specific alignment of gravity between the two planetary bodies and the egg, then surely the egg would be balanceable only at the specific time that the Sun is at the equinox point?

 Why doesn't this solar gravitational force act differently depending on latitude? We all know that most of Earth faces the Sun at an angle. If the Sun, Earth and egg all line up, why doesn't the egg tilt in the direction of the Sun (assuming the experimenter does not live at the equator)?

While we're on latitudes - contrary to what we were taught in school, the Earth is not round. It's pear-shaped. Therefore the gravitic forces in different parts of the world will vary. If what they say about the Earth and the Sun's gravity balancing is true, then shouldn't this limit the number of locations on Earth where egg-balancing can be performed successfully?

Why isn't the Moon involved in this gravitational fight? The Sun's gravitational pull may be strong enough to keep us in orbit, but the Moon is so much closer - and besides, the Moon's gravitational pull is certainly strong enough to affect the tides, so why not eggs as well?

The bottom line:

There is no real scientific evidence that says the Earth's position relative to the sun effects the balance of an egg. However, it is possible to balance an egg on end and can be done at any time of the year just for fun!






If it's your first time, find an egg with a bumpy, uneven bottom. Shake the egg to help the yolk settle and lower the center of gravity (since the yolk is suspended in the egg and is of considerable weight, it may upset the balance of the egg if allowed to bob around) - make sure you don't break the egg in the process. Then, carefully up-end the egg and try to find its center of gravity. If you are patient and determined enough, you will be rewarded with an egg standing up comically on its bottom.

Of course, if you are terribly impatient, you could always do it the easy way - sprinkle the table with salt, up-end the egg and then blow the salt away. The grains holding up the egg will be all but invisible, and nobody will be the wiser.

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