i think this page from BadAstronomy is more detailed.

You can balance them on any day, but people love their rituals, balancing an egg eventually became a way to mark the equinox

That said, anyone up for some cold hard calculations on gravitational perturbations during an equinox?

from my knowledge . during that lap chun . the magnetic field is at the centre of the earth where it is the strongest field throughout the whole year . thats why the egg can stand . but i tried on diff days . if u got the patient it will stand also . if im not mistaken . the egg stands bcz the egg yolk sink to the bottom of the egg and make it heavier and more balance . i bliv its true dont u guys think so ?

I don't see what the equinox have to do with anything. But during a solar eclipse, the sun, moon, and earth is in a line. The earth is pulling you down, while the sun and moon is pulling you up. Sort of cancelling part of the gravitational effect of the earth. So you might weigh less, as will the egg. If it weigh less, it might be easier to balance.

But how much gravitational force does the sun and moon exert on something on the surface of the earth, compared to the gravitational force exerted by the earth itself.

F = Gm/r2

G = 6.6742 x 10^-11
earth: radius = 6.371 x 10^6 m, mass = 5.9736 x 10^24 kg
moon: distance (perigee) = 3.564 x 10^8 m, mass = 7.3477 x 10^22 kg
sun: distance (perihelion) = 1.471 x 10^11 m, mass = 1.9891 x 10^30 kg

gravitational force on someone standing on the surface of the earth from ...
earth
= 6.6742 x 10^-11 * 5.9736 x 10^24 / ( 6.371 x 10^6 ) ^ 2
= 9.822 m/s/s
moon
= 6.6742 x 10^-11 * 7.3477 x 10^22 / ( 3.564 x 10^8 ) ^ 2
= 0.0000386 m/s/s
sun
= 6.6742 x 10^-11 * 1.9891 x 10^ 30 / ( 1.471 x 10^11 ) ^ 2
= 0.006135 m/s/s

I would say the moon's effect is too miniscule to matter. The sun's effect is two magnitudes bigger, but then is still probably too small to make any difference, compared to 9.8 m/s/s.

0.0000386 m/s/s is equivalent to the reduction in earth's gravitational force if you were to climb up a tower 125m high. That's about 30 floors or one-third up the Petronas Twin Towers.

0.006135 m/s/s is equivalent to the reduction in earth's gravitational force if you were to climb up a distance of 20km. The top of Everest is 8.8km above sea level. Mauna Kea is 10.2km from base to top. OTOH, the earth's equatorial bulge is 42.72km (a spot on the equator like KL, is 42km further away from the center of the earth than the north/south pole is).

One line summary: go to the summit of Chimborazo in Ecuador, and wait until the sun is directly overhead.

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Added on February 11, 2012, 7:53 pmAs far as I can tell, eggs are not ferromagnetic.

This post has been edited by dkk: Feb 11 2012, 07:54 PM

There is a small patch of air compartment at the tip of the egg and should make a difference in balancing, I notice people turn the egg to see if a particular egg can stand.

But that does not make the egg ferromagnetic.

Yes it does make a difference. I would love to see someone balance an egg on the pointed end.

What does magnetism has to to with this scenario? Its gravitational phenomena that may affect small objects, you can't compare a human with tiny insect if both fall from 100 feet high which don't injured the insect but the human, so we cannot feel it even if equinox does affect the egg for example.

I was replying to marasista who mentioned the earth's magnetic field.

The link in chiiupe post has pictures of people successfully doing that.

Are you sure. I don't see it. Looks to me like they're balancing the eggs on the rounded end rather than the pointed end.

It's the second last picture with four students in it on the article. There's a paragraph describing it just next to the picture.

With a picture and claim it stand on the eggs short ends for a month in a science lab is rather unreal, nobody use the classroom for that long or the table so stable that no vibration or breeze of wind like a vacuum chamber? They went too far trying to debunk it.

This post has been edited by 3dassets: Feb 13 2012, 07:05 PM

Who knows, maybe they did it during summer vacation when everyone is out of school for over a month? Then again, the egg that they used are much more symmetrical compared to the eggs that we have here. The pointed end is nearly like the blunt end.

That's amazing. I would have thought it impossible. Same as the author of the website himself.

Never mind one month. Getting it to stand for 1 minute on the pointed end is amazing in itself.

As for one month, perhaps they covered it with a transparent box. Or there are just a few extra tables that students do not sit at (like I observe in most school labs), especially those at the side of the room.

The eggs look all white. And the shape is not like the chicken eggs we normally see. Perhaps they're using duck eggs intead of chicken eggs. But it could be just the whitebalance on the camera.

There's still the possibility of cheating. I might try it myself later.

Come to think of it, perhaps gravitation is not an even field and fluctuate, that is why some time can and other time cannot. Also why the egg? Because there is air pocket at one end and the yolk act like an anchor that balance it. Not rocket science stuff.

I've tried it. It took about 5 minutes.

I cannot get the egg to balance on the pointed end *AT ALL*.

But I don't really have the patience to do this. Not even on the round end. I took that pix after I gave up. But how do you explain the pic? Guess how I cheated.

This post has been edited by dkk: Feb 14 2012, 10:29 PM


Attached thumbnail(s)

You poke a hole at the back and put a coin in?

No. The egg was unmodified. It is a normal chicken egg.

The kitchen top is as old as my house, around 30 years old. There are tiny imperfections. Small "holes", less than 0.5mm in diameter, many times less than that in depth. They're so small as to be only visible when seen from about 5cm away.

I place the egg on top of one of these. It was still very difficult to balance. But do-able.

My kitchen top was simply too smooth and slippery. On a different, less slippery surface, it'll probably be easier to balance the egg.

it was a Sat.

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Added on February 17, 2012, 11:36 pmCan be done on the pointed end. will post a pic soon.

This post has been edited by frankzane: Feb 17 2012, 11:36 PM

That is not what I meant. I mean to ask day and month of the chinese calendar?