This GIF Of The Earth From Space Shows Exactly What's Happening At The Spring Equinox

Today, March 20, is the first day of Spring in the northern hemisphere marked by the vernal equinox.   The equinox is cool because it's a time of year when the night and day are almost equal.  This awesome GIF of Earth from NASA's Astronomy Picture of the Day (APOD) helps to explain why that happens.   Generally throughout the year, the changes in season are caused by the Earth's tilt on it's axis. When the top of the Earth is titled toward the sun, it's summer in the north. There's more s...