The shortest day of year

The shortest day marks the point when the days start to get longer and the nights shorter, and has profound cultural meaning around the world and throughout history.

The shortest day, winter solstice and midwinter are the colloquial terms used to describe the 24 hours around an annual astronomical event which usually occurs on December 21 to 22 each year.

In the Southern Hemisphere this is the Northern solstice, the time at which the Sun is at its northernmost point in the sky, which usually occurs on June 20 to 21 each year, and marks the point when the days are longest and nights shortest.

Worldwide, interpretation of the event has varied from culture to culture, but most northern hemisphere cultures have held a recognition of rebirth, involving holidays, festivals, gatherings, rituals or other celebrations around that time.

shortest day of the year

The Earth’s position during the September equinox.

UT date and time of equinoxes and solstices on the earth

event Northward
equinox
Northern
solstice
Southward
equinox
Southern
solstice
month March June September December
year
day time day time day time day time
2010 20 17:32 21 11:28 23 03:09 21 23:38
2011 20 23:21 21 17:16 23 09:04 22 05:30
2012 20 05:14 20 23:09 22 14:49 21 11:12
2013 20 11:02 21 05:04 22 20:44 21 17:11
2014 20 16:57 21 10:51 23 02:29 21 23:03
2015 20 22:45 21 16:38 23 08:20 22 04:48
2016 20 04:30 20 22:34 22 14:21 21 10:44
2017 20 10:28 21 04:24 22 20:02 21 16:28
2018 20 16:15 21 10:07 23 01:54 21 22:23
2019 20 21:58 21 15:54 23 07:50 22 04:19
2020 20 03:50 20 21:44 22 13:31 21 10:02

Why is it called equinox?

On the equinox, night and day are nearly exactly the same length – 12 hours – all over the world. This is the reason it’s called an “equinox”, derived from Latin, meaning “equal night”.

However, even if this is widely accepted, it isn’t entirely true. In reality equinoxes don’t have exactly 12 hours of daylight

The September equinox occurs the moment the sun crosses the celestial equator – the imaginary line in the sky above the Earth’s equator – from north to south.

This happens either on September 22, 23, or 24 every year. On any other day of the year, the Earth’s axis tilts a little away from or towards the Sun. But on the two equinoxes, the Earth’s axis tilts neither away from nor towards the Sun, like the illustration shows.

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