Image © Fiona Owen.
Today is the spring equinox in the northern hemisphere and the fall equinox in the southern hemisphere at 04:30 UTC. Equinoxes occur when the number of daylight and night time hours are roughly equal. Solstices mark maximum daylight or night time hours, as the images and video from EarthSky and APOD/NASA demonstrate.
Video Source: Youtube.
Image Source: Physical Geography.