(CNN) — Thursday is the first day of spring, and the season is starting earlier than it has in more than a century.
Spring usually begins March 20 or 21, but this year the vernal equinox is March 19.
The Northern Hemisphere starts springtime when it sees equal stretches of light and darkness in a day. The middle of those periods will fall at 11:50 p.m. Eastern time this year.
However, scientists are not crediting a brave groundhog for the early season. They say it is due to leap years, centuries, and the Earth’s path around the sun.
Experts say spring has not sprung this early since 1896.