Saturday 21 March 2015

The 2015 March Equinox.

The March Equinox fell on 20 March this year. The Earth spins on its axis at an angle to the plain of the Solar System. This means that the poles of the Earth do not remain at 90° to the Sun, but rather the northern pole is tilted towards the Sun for six months of the year (the northern summer), and the southern pole for the other six months (the southern summer). This means that twice a year neither pole is inclined towards the Sun, on days known as the equinoxes.

How the combination of the Earth's equatorial plane (red circle) and the plane of the Earth's orbit (green circle) creates the Solstices and Equinoxes that we observe. Ohio State University.

The equinoxes fall each year in March and September, with the March Equinox being the Spring (or Vernal) Equinox in the Northern Hemisphere and the Autumn Equinox in the Southern Hemisphere, while the September Equinox is the Autumn Equinox in the Northern Hemisphere and the Spring Equinox in the Southern Hemisphere. On these two days the day and night are both exactly twelve hours long at every point on the planet, the only days on which this happens.

See also...

A total eclipse of the Sun will be visible from the Faroe Islands and Svalbard on Friday 20 March 2015, with a partial eclipse visible from the rest of Europe, West Asia, northern Arabia, North and West Africa, Iceland, Greenland and (briefly) Nova Scotia, Newfoundland and Labrador and parts of eastern Quebec. 

The Quadratid Meteor Shower is one of the brightest meteor showers of the year, often producing over 100 meteors per hour at its peak, which falls on the night of 3-4 January each year, and is predicted to peak at 2.00 am GMT on Sunday 4 January 2015. The...

The planet Mars will reach its perihelion (the closest point on its orbit to the Sun) at 8.27 pm GMT on Friday 12 December 2014, when it will be 1.38 AU from the Sun (i.e. 1.48 times the average distance between the Earth and the Sun, about 206 400 000 km). Mars has a significantly eccentric orbit, varying in distance from the Sun from 1.38 AU at perihelion to 1.67 AU (1.67 times the average distance between the Earth and the...

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