Page 252 - Lokmanya Tilak Samagra (khand 2)

THE ARCTIC .REGIONS 39
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tion of one such circuit, whether of the sun or of the stars, will
s~rve as a measure of ordinary days, or periods of 24 hours,
during the long sunshine or night of six months. When about
180 such rounds, (the exact number will depend upon the diff-
erence in the durations of summer and winter noticed in the last
chapter ), are completed, the sun will again go down below the
horizon, and the stars in the northern hemisphere, which had dis-
appeared in his light, will become visible all at once, and not rise
one after the other as with us. The light of the sun had, so to say,
eclipsed them though they were over the head of the observer;
but as soon as this obstruction is removed the whole northern
starry hemisphere will again appear to spin round the observer
for the remaining period of six months. The horizontal motion
of the celestial hemisphere, only one lqng continuous morning
and evening in the year, and one day and one night of six months
each are, thus the chief special features of the calendar at the
North Pole.
We have stated that to an observer at the North Pole, there
will be a night of 6 months, and one is likely to infer therefrom
that there will be total darkness at the Pole for one half the
portion of the year. Indeed one is likely to contemplate with
horror, the perils and difficulties of a long night of six months,
during which n6t only the light but the warmth of the sun has
to be artificially supplied. As a matter of fact, such a supposition
is found to be erroneous. First of all, there will be the electric
discharges, known as Aurora Borealis, filling the polar night with
their charming glories, and relieving its darkness to a great extent.
Then we have the moon, which, in her monthly revolution,
will be above the polar horizon for a continuous fortnight, dis~
playing her changing phases, without intermission, to the polar
observer. But the chief cause, which alleviates the darkness of
the polar night, is the twilight before the rising and after the
setting of the sun. With us in the tropical or the temperate zone,
this twilight, whether of morning or evening, lasts only for an
hour or two; but at the Pole this state of things is completely
altered, and . the twilight of the annual morning and evening is
each visi~le for several days. The exact duration of this mornil:~g
or evening twilight is, . however, 'still a matter of uncertainty~
Some authorities fix the period at 45 days, while others make ii
last. for full two months. In the tropical zone, we see the first