The March Equinox will occur at 4.15pm GMT today on 20th March 2018. This means it will be an equal night as the length of the day and night is the same in nearly all parts of the world. The March Equinox also known as the Northward equinox or Vernal equinox is when the Northern Hemisphere tilts towards the sun, thus meaning the world gets longer days. In the Southern hemisphere the March Equinox is known as the autumnal equinox and is the beginning of autumn and end of summer.
In the Northern hemisphere, the March equinox marks the beginning of spring and the end of winter. When it comes to astronomy it is the zero point of sidereal time, and the right ascension.
The length of the tropical year is decided by the March equinox and there are small variations in the length of the average tropical year with the mean length lasting 365 days, 5 hours and 48 minutes.
The First Point of Aries is the point when the Sun crosses northwards over the celestial equator. However now this point is actually in Pisces and by the year 2600 it will be in Aquarius.