Los Angeles herald., 1910-05-17
VAGRANT 100000
MILES AWAY TO-DAY
Tail Thinner Than Laboratory
Vacuum, Declares Director
of Lick Observatory

SAN JOSE, May 16.-Director Camp
bell of the Lick observatory today
gave out the following:
"Halley's comet was 80 degrees long
at daybreak this morning, both as
photographed and as observed by the
naked eye. This corresponds to a
length of 100000 miles. The nearest
point of the comet was 100000 miles
from the EARTH
Tuesday morning it will be nearly
100000 miles away; Wednesday morn
ing a little over 100000 miles, and
Wednesday evening the earth will be
passing through its tail. The present
diameter of the tail at the point
through which the earth will pass IS q
little over 100000 miles. The two
bodies will have a relative velocity of
about 43 miles per second, and the
time required for the passage, If pres
ent dimensions remain unchanged, will
be six or seven hours
AFTER SUNSET
Astronomer Aitkens' observations
on the positions of the head of the
comet yesterday and this morning leave
little doubt that the sun will have set
for California observers before the
head begins to transit the disc of the
sun.
"The tails of comets usually lag be-
hind the straight line drawn from the
sun through the heads for some comets
but little and for others several de-
grees. The exact time that the earth
will enter the tail is accordingly un-
certain by several hours.
1T is true that comets are the most
mysterious bodies in the sky and that
many important questions concerning
their origin and constitution remain
unanswered. We do know, however,
that the tails are so highly attenuat-
ed that the most perfect laboratory
vacuum is extremely dense in compari-
son. 1t is probable that both minute
solid particles. and isolated gas mole
cules are present in the tails, the prop
critics of solid particles to gas mole
cules varying in different comets. 1t
seems to be a conservative estimate
that there is not more than one par
ticle or mOlecule, microscopic in size,
on the average per cubic yard.
EARTHs BLANKET
"The earths atmosphere will form
a perfect protecting blanket against
all possible constituents of the tail.
There is absolutely no cause or eX-
cuse for anxiety as to injurious eff
fects upon terrestrial life, animal or
vegetable. The earth has passed
past centuries, and such an event is
of great scientific interest, not attend
ed with the slightest danger.
1T is very unfortunate that the
moon, nearly full, will interfere with
optical observations of the phenomena
attending our passage through the tail.
If the moon were absent, there is lit
tie doubt that we should be able to
see the night sky family illuminated
by that part of the tail which pro-
jects beyond the earth. Because of the
possible and probable tagging of the
tail, there is a chance that we may
still be In the tail the latter part of
Wednesday night, and that some evi-
dence of its presence may be seen in
the short interval between moon set
and dawn Thursday morning.
at is not expected that the event
will be attended by a meteoric display
to any extent. There will probably be
no more meteors observable on Dednes-
day night than on other nights.
Astronomers of the Lick's observa-
tory have been credited in newspapers
with the opinion that the telegraphic
service will not be affected We have
not expressed such an opinion. 1t would
not he surprising if telegraphic trans
mission We're interfered WITH as is
the case when strong aurOrae are
present in the sky. 1T is not impossible
that delicate appara tus viii be able to
detect magnetic variations due to the
presence of electrified cOmetary par
tcles in the highest strata Of the
earth's atmosphere. There might even
be an aurorae Of considerable inten-
sity. due to the electrically-c charged
particles visible to the eye or made
apparent by observations Of its spec
truu0 "