This year the spring equinox falls on Tuesday, March 20, marking the first of warmer and longer days to come.

So what is it all about? Here's a short guide to everything you need to know.

  • What is the spring equinox?

At 4.15pm today the sun will line up directly with the equator allowing both the Northern and Southern Hemispheres to have almost the same amount of daylight, known as the equinox.

In the Northern Hemisphere the event marks the beginning of spring and in the Southern Hemisphere it signifies the start of autumn.

  • Why does the spring equinox happen?

The changing of seasons and daylight hours has everything to do with the Earth spinning on a tilted axis.

As a result the North Pole gets more light than the South Pole for half the year.

However, during the spring equinox the Earth hits a point during its orbit when neither the South or the North pole are tilted toward the sun.

  • When will the clocks go forward?

The changing of seasons means the clock go forward by one hour on Sunday, 25 March.

William Willett first campaigned for Daylight Savings to come into force in Britain but the bill was narrowly defeated in 1909.

During World War I Britain was running short of coal and Willett's proposal of bringing the clocks forward offered a timely way of saving on fuel.