New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1910-05-20
WHY COMET WAS SHY
Too Transparent To Be Seen,
Says Professor jacoby.
ALREADY PASSED By US
Thinks Negative Views in Far
East Throw Light on What
Comet Really Is.

Harold 4 Jacoby, Rutherford professor
of astronomy at Columbia University, "hen
asked yesterday about ths reported failure
of astronomers stationed at Manila ana
Honolulu to see the actual transit OF Hal
ley's comet said:
'9The fact that they did not see the head
OF the comet in transit does no, prove tnet
it did not occur. think 1t merely means
that even the head OF the comet is so trans
parent that it could not be seen when pro-
jected against the bright disk OF the sun
This would fit in with our theory about
the constitution OF comets. This negative
result IS therefore Of importance, and not
70 be regarded as failure. We have never
had such a chance before to verify in this
way our ideas as to the lack Of density III
the comets. I think that is quite q De
Sirabie result
Referring to reports from the West Indies
and elsewhere that the comets tail was
seen in the eastern sky on Thursday morn
ing, Professor Jacoby said: IF the tall or
the comet or any part OF it was seen on
Thursday morning early in q position SINH
lar TO its former one, this observation sim
ply means that the tail, or part of It. was
really still in its old position.
That may sound almost too foolishly
simple a proposition TO state In other
words. at that hour we had not yet passed
through or by the tail. I think that the
next time we see the comet we shall ind
that the tail, if still visible, has gone
around US, Is predicted. That is to say,
when the comet becomes visible in the
western sky after sunset we shall see the
tail pointing away from the sun, as usual"
Asked. on what night we should probably
get the best view Of the comet. Mr.. Jacohy
said that, assuming q cloudless sky, the
excellence of our view Of the puzzling
traveller would depend on three factors
first, the intrinsic brightness of the comet;
second. the absence Of twilight in the sky,
and. third, the absence Of moonlight
The brightness of the comet is diminish
ing, he said, so that this factor is becom-
ing less favorable as the comet moves fur
Their from the earth night after night. But,
he added. the other two factors will become
more favorable because the comet will set
later each evening, giving an opportunity
to await the disappearance of twilight and
because the moonlight will also diminish
after the full moon on May %
cit follows that as these factors are act
ing in opposite directions we cannot fore
tell" said Mr.. Jacoby, 'the exact date
when the sum of their effects will be most
favorable. It would not surprise me if we
have better view on Saturday week than
we shall have this Saturday.
There is going to be q total eclipse Of
the moon on the 3d." continued Mr.. JAG
oby. Those who have noticed how badly
the moonlight interferes with observations
of the comet may have been looking for
ward TO this eclipse as an opportunity to
view the comet without moonlight. In fact,
statements to this effect have appeared in
some OF the newspapers. Unfortunately, at
New York the eclipse will not begin until
Just about the time when tie comet will
set, so we shall probably get little help
from the eclipse