When is the first day of spring in 2019, how’s the equinox date decided and does it change each year?


As flowers start to bloom and the sun brings back its warm rays, spring must be around the corner.

But when does it actually start? Here’s our guide.

The spring brings a welcome change in the weather after the chills of winter
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When is the first day of spring in 2019?

How you define the start of spring depends on whether you follow the astronomical or meteorological seasons.

Traditionally spring begins at the vernal equinox – which next year falls on March 20.

Summer does not officially start until the solstice on June 21.

Weathermen follow the meteorological calendar, which defines the seasons differently.

It says spring starts on the same date every year – March 1 – and runs until May 31.

Spring will arrive on March 1 or March 20, depending on your preference of seasonal calendar
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How is the equinox date decided and why does it change each year?

There are two equinoxes each year, around March 20-21 and September 22-23.

They are when day and night are approximately 12 hours each everywhere on Earth. The word comes from the Latin for equal night.

After the spring or vernal equinox, days are longer than nights in the northern hemisphere, and vice versa in the south.

The equinoxes are the only two days of the year when the north and south of the planet get the same amount of sunshine.

Astronomers can calculate the precise moment of equinox when the Sun appears directly over the Earth’s equator.

In 2019, the vernal equinox falls at 9.58pm GMT on March 20. The autumnal equinox is at 7.50am GMT on September 23.

The time gets later by just under six hours from year to year because the orbit of the Earth around the Sun is not exactly 365 days.

An extra day in Leap Years keeps the calendar in step with the seasons, but it means the date of the equinoxes can vary by a day or so.

What causes the seasons?

While day and night are caused by the Earth spinning every 24 hours, the seasons are due to our year-long orbit around the Sun.

The Earth’s axis of rotation (a line through the centre from pole to pole) is tilted by 23.5 degrees from the plane of orbit.

It means for half the year the northern hemisphere gets more daylight than the south, and it is the other way round for the rest of year.

In our summer months, the north of the planet is tilted towards the Sun, which appears high in the sky, and the days are long.

In winter we are angled away from the Sun. Days are short and the Sun appears low in the sky.

In spring and autumn, the tilt is sideways to the direction of sunlight.

The amount of sunlight reaching our part of the globe affects the weather we get at different times of year.




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