![]() ![]() So, thanks to February having an extra day in 2000, the date of the equinox slipped back a day to March 20.ĭaylight saving time delayed the equinox in the Eastīecause the solar year is not exactly one-quarter of a day longer than the 365-day calendar year, but a little bit less than one-quarter (24.22%) of a day, the occurrence of the equinox comes about 47 minutes earlier (on average) every four years: Hence, the reason we have an asterisk next to that date. Had we skipped the leap year in 2000 (as in 1900), then the vernal equinox in 2000 would have occurred a day later, on March 21 at 2:35 a.m. That's why 1700, 18 were not leap years.īut 2000 was a century year, evenly divisible by 400, so it was observed as a leap year. The exceptions were those century years equally divisible by 400. In order to better adjust the new calendar format to more closely match the length of the solar year, most century years (such as 1700, 1800, 1900) - which in the old Julian calendar would have been observed as leap years - were not. First, to catch things up, 10 days were omitted after Oct. It was then that Pope Gregory XIII stepped in and, with the advice of his own astronomer, Christopher Clavius (1538-1612), produced our current "Gregorian" calendar. ![]() By the year 1582 - thanks to the overcompensation of observing too many leap years - the calendar had fallen out of step with the solar year by 10 days. Unfortunately, the new Julian calendar was 11 minutes and 14 seconds longer than the actual solar year. So to account for that residual quarter of a day, an extra day - leap day - was added to the calendar every four years. In 46 B.C., Julius Caesar's consulting astronomer, Sosigenes, knew from Egyptian experience that the solar year was about 365.25 days in length. Note that each year the occurrence of the equinox happens about 6 hours (or one-quarter of a day) later in the calendar: Let's look at the dates and times of the vernal equinoxes leading up to 2000. Rather, it is the leap year that we observed in the year 2000. (Image credit: NOAA) When a leap year set us back a dayįirst, that 2020 is a leap year (meaning that the month of February had one extra day) is not the reason for the early arrival of this year's equinox. NOAA's GOES-13 satellite captured this image of the Earth at the spring equinox on March 20, 2013. There are two specific reasons for this variation of the date: leap years and daylight saving time. Why so early?Īs was noted, this will be the earliest that the vernal equinox will occur across the contiguous United States in 124 years. In the days that follow, the direct rays of the sun migrate to the north of the equator and the length of daylight in the Northern Hemisphere will correspondingly appear to increase. ![]() At that moment, the sun will appear directly overhead about 50 miles (80 kilometers) south of Gorontalo, a province of Indonesia - often referred to as the "Emerald of the Equator" - on the island of Sulawesi, on the equator in the Gulf of Tomini. This year it will occur on Thursday (March 19) at 11:49:28 p.m. Sun overhead from the Emerald of the EquatorĪstronomers can calculate the moment of the vernal equinox right down to the nearest second. At the latitude of New York, for instance, day and night are roughly equal a few days before the equinox, on St. The spring will last until the summer solstice, which occurs on June 20 or June 21 in the Northern Hemisphere and December 21 or December 22 in the Southern Hemisphere.The supposed equality of day and night gives us the Latin name "equinox," which means "equal night." But in reality, thanks to our atmosphere, the day is longer than the night at the equinox. The vernal equinox happens in the Northern Hemisphere around March 20 or March 21, whereas in the Southern Hemisphere is occurs around September 22 or September 23. Over the next three months, the sun will move higher and higher in the sky, resulting in longer periods of daylight. The word "equinox", literally means "equal night", as it derives from the Latin "aequus" (equal) and "nox" (night). In this case, the Earth's axis isn't tilted towards or away from the sun, meaning there are 12 hours of daylight and 12 hours of darkness all over the planet. The vernal equinox happens when the Earth's axis reaches a particular position and the centre of the sun is directly above the Equator, meaning that both day and night are of approximately equal length. Spring 2022 has finally arrived, and will be marked by the vernal equinox, which takes place on this Sunday, March 20. ![]()
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