|
Spring
is almost with us. At times it may be hard to believe - dull damp
days and dark evenings. But at the same time the daffodils and crocuses
are already up and many species of tree are in bud.
At
the North Pole polar bears will be enjoying daylight for the
first time in six months, whilst at the South Pole penguins
will be saying goodbye to the sun for the next six months.
 |
| Richard
Angwin |
Therein
lies a dilemma. Does spring begin on the 1st of March, or is the
spring equinox the true indicator of its arrival?
For
the Met Office the answer is simple. Spring starts on the first
day of March. Statistically, it is much easier to calculate data
which begins and ends on the 1st and 31st respectively. So what
is the significance of the spring, or vernal, equinox?
Put
simply, this is the time of year (repeated at the autumn equinox)
when days and nights are of equal length and every point on the
Earth will, for that day, experience 12 hours of darkness and 12
hours of daylight.
At
the poles it is a date of even greater significance. At the North
Pole polar bears will be enjoying daylight for the first time in
six months, whilst at the South Pole penguins will be saying goodbye
to the sun for the next six months.
The
equinoxes occur because the axis of the Earth’s orbit around
the Sun is inclined at an angle of 23.5 degrees. At the winter solstice
the Northern Hemisphere is tilted furthest away from the Sun which
appears to be over the Tropic of Capricorn.
At
the vernal equinox the Sun’s apparent position is on the celestial
equator and it then continues its northward journey until the summer
solstice, at which time it reaches its greatest northern extent,
over the Tropic of Cancer.
 |
| Penguins
say goodbye to the light |
Whilst
there are no direct changes in the weather brought about by the
vernal equinox, it does have religious and cultural significance
attached to it.
It
used to be considered as the beginning of the Pagan New year, a
time of joy and celebration of the return of the Sun God from the
winter underworld. It has, of course, been incorporated into Christianity.
Easter Day is the first Sunday after the first full moon that occurs
after the vernal equinox.
One
rather curious misconception surrounding the vernal equinox is that
it is sometimes claimed that on this it is possible to stand a raw
egg on its end! This nonsense is popular on the other side of the
Atlantic. In case it should gain a foothold on this side, then yes,
an egg can be stood on its end on the date of the vernal equinox.
But then the same feat can be achieved on any other day of the year.
For
the record, the 2003 vernal equinox this year occurs at 0059 on
the 21st March.
by
Richard Angwin
|
