The vernal equinox is what marks the official start of spring. The reason we have seasons is all due to the tilt of the earth’s axis.
Earth is tilted at a 23.5 degree angle. The angle causes some areas on our planet to receive more sunlight and some to receive less, depending on the time of year.
During the equinox, there is an equal amount of daylight and darkness. In other words, we see 12 hours of daylight and 12 hours of darkness. This is true no matter your location on the planet.
We have our vernal equinox as we transition to spring and our autumnal equinox as we transition to fall.
The days start to get longer after the vernal equinox where we live. In other words, the north pole is tilted toward the sun. This results in more daylight and shorter nights.
The opposite is true for the autumnal equinox and winter in the north pole.
For 2019, the vernal equinox will occur at 5:58 p.m. on Wednesday, March 20.