Before the clock and the calendar were invented, our ancestors had a way of determining time and date, such is to determine it based on the sun's position. One of the most noted astronomical events is called the equinox.

According to Earth and Sky, an equinox occurs when the sun aligns directly with the Earth's imaginary line called equator.

Below are other interesting facts about equinox, particularly the autumn equinox:

  1. It happens twice a year, during spring and fall. The first equinox of the year takes place during March and the other in September.
  2. Equinoxes happen at the same moment everywhere -- the autumnal (fall) equinox in the Northern Hemisphere and the spring (vernal) equinox in the Southern Hemisphere. In the Northern Hemisphere, the September equinox has arrived. Earth and Sky notes that for time zones in the continental U.S., this equinox comes at 10:21 a.m. EDT, 9:21 a.m. CDT, 8:21 a.m. MDT or 7:21 a.m. PDT.
  3. "Equinox" comes from the Latin words equi meaning "equal" and nox meaning "night." Though this implies that there will be equal length of day and night, that is not exactly what happens as the light is still defined by the atmospheric refraction of sunlight.
  4. One fact is that although the day and night will not be equal, the days will now get shorter until the winter solstice in December.
  5. The astronomical season is different from meteorological seasons. For meteorologists, fall in the Northern Hemisphere begins weeks before the September equinox. Portland Press Herald says this is because meteorologists depend on seasonal temperatures, not the position of the sun.
  6. According to Space.com, during an equinox, the chances to see the aurora borealis increases. Janet Green, a physicist at the National Oceanic and Atmospheric Administration (NOAA), told the site that the times around the equinoxes are when geomagnetic storms are strongest, resulting to frequent aurora displays.