It’s the autumn equinox at 8:21am on 23rd September, but what is it ?
The Earth sits on a 23.4 degree angle tilt and as a result, the northern and southern hemisphere either point towards or away from the Sun depending on the time of year.
When the northern hemisphere points towards the Sun it is summer here in the UK and when it points away it is winter.
Twice a year during the Earth’s orbit neither hemisphere directly points towards or away from the Sun, resulting in a equal amount of daylight and darkness, this is called an equinox.
So on September 23rd the autumn equinox will occur, daylight and darkness will be equal duration, after that night’s will become longer than days.
— Simon Proud (@simon_rp84) September 23, 2015