This year’s vernal equinox takes place this Saturday morning at 9:37am GMT – officially marking the arrival of spring for the Northern Hemisphere.
The equinox marks the point when the Sun appears to shine directly over the equator and daytime and nighttime are nearly equal lengths.
After the vernal equinox, the Northern Hemisphere will start seeing more hours of daylight than darkness each day.
The astronomical event, which has been celebrated for centuries, is seen as heralding new beginnings and the renewal of the natural world.
Stargazers in the Northern Hemisphere will also be able to enjoy views of Mars and several constellations on Saturday night without a telescope.
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There are two equinoxes every year – in September and March – when the Sun shines directly on the equator and the length of day and night is nearly equal. During equinoxes, we experience pretty average temperatures and equal lengths of day and night
The Red Planet will be visible in the southwest around sunset, in the V-shaped constellation of Taurus, according to Royal Observatory Greenwich.
The famous constellation Orion will be visible in the south on Saturday night just after sunset, as it travels across the sky and sets in the west around 11pm GMT.
Leo the lion rises in the east around sunset, travels across the sky throughout the night and sets in the west around sunrise, the observatory told MailOnline.
And for those who are up for camping out in front of the stars until Sunday morning, Ursa Major, the great bear constellation, is high in the north of the sky all night.
There are two equinoxes each year – one in March called the vernal equinox, and one in September (heralding autumn for the Northern Hemisphere) called the southward equinox.
‘This Saturday marks the vernal or spring equinox, one of two points in the year when the number of daylight and night-time hours are the same,’ Anna Ross, an astronomer at the Royal Observatory Greenwich, told MailOnline.
Orion is one of the most easily recognisable constellations in the world. The famous constellation will be visible in the south on Saturday night just after sunset, as it travels across the sky and sets in the west around 11pm GMT
Mars will be visible in the South West around sunset, in the V-shaped constellation of Taurus (pictured)
‘The Earth takes one year (or 365-and-a-quarter days) to orbit once around the Sun and it is tilted over slightly on its axis.
‘So for half of the year, the Northern Hemisphere is tilted slightly towards the sun, meaning we have longer daylight hours and hotter temperatures.
‘For the other half of the year, we are tilted slightly further away from the Sun so we have longer nights and colder weather. It’s this tilt that gives us our seasons.
‘There are two points in the year where the Earth’s tilt is at its most extreme relative to the Sun.’
While the vernal equinox marks the point at which the Northern Hemisphere enters spring, the Southern Hemisphere enters autumn.
For the Northern Hemisphere, the vernal equinox kicks of the countdown to the summer solstice – the longest day of the year and the start of summer – which this year will be on June 21.
Solstices – which are essentially the opposite of the equinoxes – occur when the planet’s geographical pole in the Northern or Southern Hemisphere is most greatly inclined towards the Sun.
‘There are two points in the year where the Earth’s tilt is at its most extreme relative to the Sun,’ said Ross. ‘These days are known as the solstices.
‘On these dates, depending on which hemisphere you live in, you will either experience midsummer with the longest day of the year or midwinter with the longest night.
‘In between both of these extremes, we get our spring and autumn months, with the exact midpoints being the equinoxes.’
The vernal equinox, which has been celebrated for centuries, is seen as heralding new beginnings and the renewal of the natural world
Tomorrow marks the start of ‘astronomical spring’, which is one of two definitions of when the seasons start and end.
Astronomical spring is different from meteorological spring, which always commences on March 1 and ends May 31.
Meteorological seasons are based on the annual temperature cycle and are more rigidly defined by the months of the year.
The Met Office explains: ‘These seasons are split to coincide with our Gregorian calendar, making it easier for meteorological observing and forecasting to compare seasonal and monthly statistics.’