Autun Equinox: What is the yearly event and why is it different to when the clocks change in the UK?

The official start of Autumn is here.

Each year, the Autumn Equinox signifies a major point in the calendar and the event this year is coming up this week. But what makes the equinox an important event, and why doesn’t it link up with the dates the clocks change in the UK to signify the end of British Summer Time?

What is the Autumn equinox?

Scientifically speaking, the Autumn equinox is when the sun appears to cross the celestial equator. More simply, equinoxes get their name from the Latin for equal night and describes the only two times in the year when the equator is the closest part of the earth to the sun.

Penshaw Monument sunset.

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    This means everywhere on the planet should get around 12 hours of daylight and the line between night and day, as seen from space, should go between the north and south poles exactly. This isn’t always the case though because of how we see daylight through the earth’s atmosphere.

    For six months every year, either the northern or southern hemisphere is pointing slightly towards the sun with the equinox being celebrated on the day it does neither. This tilt impacts the seasons with part of the world leaning towards the sun experincing summer.

    This is why the Autumn equinox is also seen as the start of Autumn in the northern hemisphere.

    When is the Autumn equinox?

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    Each year the equinox falls on one of two days in September, with this year’s event falling on Friday, September 23. The event will be at its peak at 1:04am.

    Why don’t the clocks change on the Autumn equinox?

    The main reason we have Daylight Savings Time is to make better use of the daylight available. Although Autumn officially starts following the Autumn equinox, the clocks change later in the year to ensure any light is able to be used.

    When do the clocks change in the UK?

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    Each year clocks in the UK go forward one hour at 1am on the last Sunday in March and go back one hour at 2am on the last Sunday in October.

    This Autumn, clocks will go back at 2am on Sunday, October 30.