On the day of the equinox, the geometric center of the Sun's disk crosses the equator, and this point is above the horizon for 12 hours everywhere on the Earth. However, the Sun is not simply a geometric point. Sunrise is defined as the instant when the leading edge of the Sun's disk becomes visible on the horizon, whereas sunset is the instant when the trailing edge of the disk disappears below the horizon.
At these times, the center of the disk is already below the horizon. Furthermore, atmospheric refraction or bending of the Sun's rays cause the Sun's disk to appear higher in the sky than it would if the Earth had no atmosphere. Thus, in the morning, the upper edge of the disk is visible for several minutes before the geometric edge of the disk reachs the horizon. Similarly, in the evening, the upper edge of the disk disappears several minutes after the geometric disk has passed below the horizon.
For observers within a couple of degrees of the equator, the period from sunrise to sunset is always several minutes longer than the night. At higher latitudes in the Northern Hemisphere, the date of equal day and night occurs before the March equinox. Daytime continues to be longer than nighttime until after the September equinox.
In the Southern Hemisphere, the dates of equal day and night occur before the September equinox and after the March equinox. The chart shown below shows the dates and times for the equinoxes and solstices through Times listed are in Eastern Time.
Subtract one hour for Central Time. The answer is YES. However, you can stand an egg on end, with a large amount of patience, on any day of the year. This myth seems to pop up every year around the equinox.
The thought that an egg can only stand on end on the spring equinox due to gravitational forces of the sun being aligned with the earth sound like science, but it isn't. According to Chinese tradition, an egg can be made to stand on end at the precise moment winter ends and spring begins.
But, the Chinese calender had this transition occurring at a variable time each year, determined partly by the Chinese lunar month, usually in early February. Indoor Exhibits Year-Round. Outdoor Sports Experiences March-Nov. Future Exhibits. Live Theater Shows.
Press Room. Annual Report. Official Partners. Make a Donation. Donor Memberships. Become a Member. Gift Memberships. Code of Conduct. Gift Certificates. Group Visits. Birthday Parties. Private Events. Special Events. Full Calendar. Public Events. You might not have heard this one: Some people believe that you're more likely to balance eggs upright on a flat surface during the spring equinox when the Earth's axis does not point toward or away from the sun.
But balancing an egg isn't any more likely during the equinox, or the summer solstice, for that matter. It is a misconception that the Earth's axis is somehow shifting in response to the changing seasons. Here's how: take a dozen eggs and shake each one until the yolks break up a bit inside the shell so that it can move more freely.
Next, put the egg back in the carton to settle the yolk further down. When you try placing the egg on a flat surface it will stand upright because it has become more weighted at the bottom. Myth No. John Matthews, a historian who wrote the book "Summer Solstice: Celebrating the Journey of the Sun From May Day to Harvest," says people often assume modern-day Druids are sun-worshippers, but "that's not quite true.
The equinox, explained: The spring equinox occurs when the Earth is tilted parallel to its path of motion around the Sun, which makes the length of the day and the night exactly the same. The idea that an egg could balance on this day comes from the thought that since the Sun and Moon are equidistant from the earth, the pull of gravity is equalized and therefore an egg is less likely to fall over. You would not have time to balance your egg!
A balancing act: Is it possible to balance an egg in an upright position? The key is finding an egg with a yolk centered in the shell.
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