It may not feel like spring in parts of the U.S. on Tuesday, but as of a little after 11 p.m. EDT, it’s officially here.
The vernal equinox marks the start of the spring season for the Northern Hemisphere. According to Space.com, this will be the earliest that the vernal equinox will occur across the contiguous United States in 128 years.
What is a vernal equinox and what does it mean for the U.S.? Here are a few things we know about Tuesday’s event:
- At the equinox, the Earth will have reached the point in its orbit where its axis is at right angles to a line from the sun. That means that the sun will then be directly over a specific point on the Earth’s equator moving northward.
- For most of the year, the Earth’s axis is tilted either toward or away from the sun. The sun’s warmth and light fall unequally on the northern and southern halves of the planet depending on the Earth’s tilt, The Associated Press explained. During the equinox, the light and warmth are evenly distributed.
- This year, the equinox happens at 11:06 p.m. Eastern Daylight Time on Tuesday.
- The Northern Hemisphere’s vernal equinox can land between March 19 and 21, depending on the year.
- It is so early this year for two reasons, according to Space.com. The first is that it is a leap year. The second is because of daylight saving time.
- The equinox is not the same thing as a solstice. A solstice is when the Earth is at its most extreme tilt. There are two solstices in a year — in the summer and in the winter. The summer solstice happens between June 20 and 22. The winter solstice happens between Dec. 20 and 23.
- There is also an autumnal equinox. It takes place this year on Sunday, Sept. 22, at 7:43 a.m. EDT.