March Equinox: Fair Game Between Day and Night
By Mohamed Adel
Do you ever feel sad when the day ends and feel like the long night has begun? Or ever felt like the day just wouldn’t end and you just couldn’t make most of the night? Or maybe you are one of those people who love symmetry and wish the day would equal the night, just to keep both sides happy. Well, last Tuesday marked that legendary day; the March Equinox. It is one of two days in the entire year when the day actually equals the night. Now you can satisfy your OCD and sleep at ease.
The word “Equinox” is derived from the Latin words “equi” and “nox” which mean “equal” and “night” respectively. Around the 20th
of March and the 23rd
of September, this phenomenon occurs to, in some cultures, mark the start of spring.
So what exactly happens in this occasion is that the Earth’s equator passes through the center of the Sun’s disk. The Equinox is the only time that the Solar Terminator (cool name, huh?) which is the border between night and day becomes perpendicular to the equator. This means that both the southern and northern hemisphere are illuminated by the same degree.
This event is also important for some cultures as mentioned before because in most cultures it marks the beginning of spring and in the Persian calendar, it marks the New Year. The September Equinox marks the beginning of autumn.
The time of the event was set as the 25th
of March when Julius Caesar created the Julian calendar. But because of the difference between the Julian year and the tropical year, this date shifted to the 20th
and then went all the way back to the 11th
of March. This change in the dates pushed Pope Gregory XIII to create the Gregorian calendar and by the help of astronomers they omitted the suitable amount of number of days to make the Equinox bounded to the range of the 19th
to the 21st
of March, so that it doesn’t conflict with the Easter Day.
Unfortunately this event goes unnoticed by most people because they don’t have the time to concentrate on the length of the day and night. But for those who are interested in Science (as a hobby or a profession) must find this phenomenon amazing. And spiritually, of course, people would find this phenomenon as a proof of a grand design.