On March 20, 2017 at 10:28 am Greenwich Mean Time is the March Equinox. An equinox is the moment in which the Earth’s equator passes through the center of the Sun, which occurs twice a year.

On an equinox, day and night are of approximately equal duration all over the planet. They are not exactly equal, however, due to the angular size of the sun and atmospheric refraction. To avoid this ambiguity, the word equilux is sometimes used to mean a day in which the durations of light and darkness are equal.

One effect of equinoctial periods is the temporary disruption of communication satellites. For all geostationary satellites, there are a few days around the equinox when the sun goes directly behind the satellite relative to Earth for a short period each day and can temporarily disrupt or degrade the circuit. The duration of those effects varies but can range from a few minutes to an hour.

Summarized from Wikipedia “Equinox”