Happy Autumn(Or Spring if you live in the Southern Hemisphere).
Today, 23 September 2015 is the day the earth has its equinox. This happens twice annually. 21 March 2015 was the last equinox. For the Northern Hemisphere, the September equinox means the first day of autumn, and the first day of spring for the Southern Hemisphere.
What happens? The Earth’s equator is at a point where it’s centered with the sun. Because of the earth’s position to the sun, most areas of the earth will get rough 12 hours a daylight. Equinox comes from the Latin for “equal night” referring to relative parity in daylight hours vs hours of darkness.
The North Pole will see the sun for the last time at 12:00PM on 23 September 2015. After that, darkness until March. For the South Pole, from this day until March, there are 24 hours of daylight.
This video will provide a hands on explanation of the equinox and how it works: