Vermont phÅ“nix. [volume] (Brattleboro, Vt.) 1834-1955, 1895-09-06
A Lunar Eclipse.
The How and why of Tuesday Nights
Show Event in the Heavens.

The How and why of Tuesday Nights
Show Event in the Heavens.
The total eclipse of the moon Tuesday
night was observed under unusually fav-
orable circumstances, and the event makes
the Boston transcripts very ineligible
explanation of the phenomenon of inter
est: In order to get vivid idea of the
reality underlying the appearances, we
must imagine our moon as a globe, 2163
miles in diameter, revolving about the
earth at distance varying between 22l,-
600 and 253, 900 miles, plunging with We
locity of 1000 miles an hour into the i'm
mense, dark, cone-shaped shadow which
the earth is made to project into space
away from the sun. In the present eclipse
the base of this cone is a circle of the earth
nearly 5000 miles in diameter, and its
height is 1854, 900 miles, its point or vertex
being more than 100000 miles beyond the
moon. At the distance of the moon land
the moon happens to be in apogee and al
most at its grestest possible distance) 252,-
400 miles, the breadth of the shadow is 300
miles, and it takes the moon two hours and
fifty minutes to traverse it. The axis of
the shadow being in the line joining the
centres of the earth and sun sweeps
over the plane of the earth's motion once
every year. This plane is called the plane
of the ecliptic, because eclipses always oc-
cur in it, If the moon also moved in this
plane it would be obliged when full to pass
through the shadow about once every
month and be eclipsed; but on account OF
the inclination of its orbit, it crosses the
plane in two points only, called respective
| ly the moons ascending node and descend
ing node. In the course of the calendar
| a., = ,I,,I
Joining the nodes either two or three times
at intervals of something less than six
months. Generally when this event takes
place the moon is somewhere else in its
orbit and escapes observation. If, how
ever, as in this case, when the moon ar
rives at the node it finds the shadow is
there too, it must pass through it. This
explains not only the occurrence OF lunar
eclipse but also why it is there can be only
two or at most three lunar eclipses in a
year, and then separated by intervals OF
about six months. AS the moon requires
but two weeks to travel from one node tC
the other and the suns relative motion
during that interval is small, an eclipse o.
the moon is very often preceded or follow
ed by an eclipse of the sun. AS this eclipse
is nearly central it is both preceded anc
followed by solar eclipse, Aug. 20 an(
Sept. IS respectively. In the former cas-
the moon is a little above the ecliptic, an(
hence the eclipse is visible only about tn
north pole, and in the latter case the moor
is below and the regions of visibility are il
the Southern Pacific ocean in the vicinit
the South pole,
1t is a curious fact that the moon doe
does not usually entirely disappear iron
view when totally eclipsed. Its face re
mains more or less feebly illumined, an
its more prominent markings are seen will
out difficulty. The hue of the central POI
lions of the disk is variously described
different eclpses as "dusky brown,
"deep-red coppery chocolate" chocolat
red "cherry red" and "pinkish." Tn
5 edges exhibit shades of blue, green or pu
q pie, probably the, complementary colors b
contrast with the central tint. The entil
r appearance is occasionally ghastly in I'll
extreme, and the moon is so ashy gray
! to look "sick and troubled"