Equinox explained

Float through any social event with M's fast facts. This week John Mather explains the equinox THE BASICS An equinox happens twice a year when the sun is perpendicular to the Earth's equator. When this happens, night and day are equal in length - equinox means "equal night" in Latin. THE SCIENCE The Earth's axis is tilted, so at different times of the year the northern and southern hemispheres lean closer to the sun. The hemisphere leaning towards the sun enjoys longer days, while the other is stuck with more darkness. The further away from the equator, the more dramatic the change - parts of the Poles gain or lose about 15 minutes of daylight every day after an equinox. The current equinoxes occur in September and March.

THE SIGNIFICANCE In Iran, the vernal equinox marks the beginning of the Persian New Year. In Judaism, Passover is observed on the first full moon after the equinox. Christians mark Easter on the first Sunday after the first full Moon after the equinox. And in Annapolis, Maryland, sailors burn their socks on the equinox to welcome spring's warmer weather. THE MYTH Due to a supposed balancing of gravitational forces, you can balance an egg on its bigger end on an equinox. This is partly true: you can, in fact, balance an egg on any day of the year.

THE CONVERSATION If it's the 20th or 21st, find someone gullible. Tell them the equinox egg myth. Find an egg. Make the egg balance. Look like a genius.