That happens at some point on the equator, at a single moment, on two days of the year ... near March 21 and near September 21.
March 21 is the approximate date of the vernal equinox (first day of spring). Depending on the rotation of the Earth the equinox may be a day earlier or a day later.
You're describing an Equinox -- either March 21 or September 21.
The next equinox is the autumnal equinox, which falls on September 22nd in the northern hemisphere and March 20th in the southern hemisphere.
March 21 1962 was a Wednesday.
Umm... It kinda happens once in a year and is on December 21 which means it has the least amount of day in the whole entire year and by the way just for your extra information, the Summer Solstice happens on June 21 and the Spring Equinox at March 21 and Fall Equinox at September 21.
March 21. 2009 March 21. 2009
March 21, 1966 was the 3rd Monday in March for that year.
San Antonio - March 17-21. Houston - March 17 - 21. Austin March 17-21. Corpus - March 17-21. Dallas March 10-14.
March 21 1994 was a Monday.
March 21 1964 was a Saturday.
March 21 1946 was a Thursday.