New-York tribune., 1900-04-15
THE ROTATION OF VENUS.
NEW LIGHT OBTAINED ON A MUCH De
RATED PROBLEM.


which is just now such a conspicuous and lovely
object in the evening skies and which should
continue to gain slowly in brilliancy until the
close of May.
Two opinions have been entertained as to he
length of a day Venus. or, in other words, the
time required by her for one complete revolution
on her axis One theory is that Venus always
presents the same side to the sum- just as the
moon does toward the earth. If this notion be
correct. her day and year are Identical To be
sure with one side always directed toward the
centre of the solar system there would be no
alienation of light and darkness. The dark
regions would remain dark and the light ones
light But a single axiaI revolution would be
executed once with every complete circuit of
the planets orbit, which requires about two
hundred and twenty-five days. or seven months
and half.
The other theory IS that Venus rotates much
more swiftly, accomplishing a revolution IN a
trihe less than twenty-four terrestrial hours
The estimates of different astronomers do not
agree precisely. but the majority adopt 23 hours.
II minutes and some odd seconds The elder
and younger Cassinis. De Vico and Schr0ter
have been advocates of the short period theory
whereas until recently Schiaparel was almost
alone in holding to the long period Observa-
tions made by Perciva Lowell at Flagstaff
three or four years ago led him to declare ms
adhesion to the great Italians theory
Before mentioning the latest contribution to
the discussion it may be pointed out that the
evidence which these men have all relied was
the faint markings sometimes seen on the sur
face of the planet. Night after night or day
after day at the same hour the planet presents
exactly the same appearance in this respect.
But such phenomenon could be explained
equally well by either of the foregoing assump-
In hPr rot ne testimony that
now offered is of a new kind-that IS,
applied to Venus The Russian astronomical
spectrosCOpist BelOposky. of Pulkowa, has been
using a spectroscope on the planet. and has
photographed the spectra observed y con-
densed cable dispatch says that he has con-
cuded from a study Of these photographs that
the rotation period is short From this phrase
it may be inferred that he adopts the view of the
Cassinis De Vico and Schr0ter and rejects that
| of Schiaparelli.
The scientific world will await a confirmation
of this verdict by some other astronomer who
employs the same means before accepting it as
final But BeOpOlsky is a recognized authority
in stellar spectroscoDy and the kind Of evidence
on which he relies is less equivocaI and ambig-
uous than that heretofore presented y spectre
scope not only indicates the chemical cOnstitu-
ton of celestial bodies but also the OF their
| motion toward and away from the observer
| Splendid work, for instance, is now being done
by Professor Campbell at the Lick Observatory
in measuring "veIocities in the line of sight"
and this computation is based on the amount of
detection side the other Of the nor
mai position of certain lines in the spectra of the
stars under scrutiny Again, by observing the
| difference between the behavior of the spectrum
| of edge of the tthe advancing) and the
! other (the recedinS) it has been possible To OBJ
| tain new information regarding the suns rOta-
| tion. Similarly. Professor Keeler made ex-
! quisite and famous examination of the
| inner and outer edges of Saturn's rings whereby
/ he was enabled To say positively that the ring
| could be a solid object because the move
| ments were not simultaneous
! 1t appears that the Russian SpectrOScopist has
! improved the opportunity furnished by the pres
| ent close approach of Venus to US to obtain
| -spectrogrdms'' Of her edge, and by noting the
amount of shifting of the lines from the position
/ which they would occupy if Venus were notion
/ less has secured a fresh clew to the rapidity of
! the rotation of the planet which most closely
| resembles the earth in size. and which, except
| for the moon and asterOid is our nearest
/ neighbor in the skies. 1t looks if Venus had
! days and nights, after all. and days and nights
/ of the same length as the earth'S.