Omaha daily bee., 1896-11-07
StorI, In sIpht.
nNNs NNNM LONG.
Enrth's Fate VIII Ultimately Hc TINT
of Venus nnd Mercury.

!
rotate on their axes. each In the same timc
in which It rcyolvcs around the sun, must
be understood, says the Philadelphia Rec
ord as simply confirming observations made
by Schiararelli at Milan nearly twenty
years ago, In the case Of Venus, and ten
years ago In the case Of Mercury.
Tho rotation period Of neither OF these
planets has ever been considered as salts
tacturily determined in all OF our textbooks
! OF astronomy; that Of Venus Is given as
| probably about twenty-three hours.
twenty-five minutes. and that OF Mercury
as twcnty-four hours. with the same pro-
NiSo as to certainty The diEculty In de-
Gliding this matter Of rotation arises from
the fact that both planets present to us
disks that are practically spctcss There
are upon them no well-deflncd markings. as.
there are upon Mars and Jupiter which en-
able the astronomer to see how fast they
are turning on their sNCs or whether they
are turning at all. Indeed, were II not for
their ever-changing phasos-for both Venus
and Mercury emulate Cynthia" as Calico
said of the former In his famous anagram--
neither of these planets would be particu-
larly interesting as a telescope object.
The first determination OF the rotation
period OF Venus was made in 1867 by tho
elder Cassni, ana was based upon obserVa-
tons upon a certain bright spot which hc
detected near the southern horn when tho
planet was In crescent phase. The con-
cluStun At which Cgssini arrived was that
the planet turned on its axis once in about
twenty-three hours. SuhscquCntly-in 1926
-Bianchni thought he could distinguish
three seas in the equatorial regions OF
the planet and one near each pole and from
observations upon these spots ne obtained
a rotation period Of twcnty-four days and
eight hours The younger Cassiui showed,
however, that the observations Of Bianchini
could be made to harmonic with those OF
his father and that from both combined a
Period Of twenty three hours and twenty
one or twenty-five minutes could be OBJ
tanned. Shroetor next attacked the problem
near the close OF the last century taking "a
his marker a peculiar bluntcd appearance
presented at times by the southern cusp OF
the crescent, an appearance which he at
lrlbuted to Il shadow east by a lofty noun
tain supposed TO be on this part of tho
planets surface. Shroctcr concluded that
the period OF rotation was twenty three hours
twonty-onc minutes. Finally. in 1876, Ia
Woo, AT Rome. determined the period deli
rttoly NlammuIiunl da tWOniy-thrrp hours
."entE-onc minutes, twenty-five seconds.
one would suppose in view OF the SUBJ
Slantial agreement Of the several determine
uons given above. that this matter might be
considered as fairly well decided The fact
is that In all OF these observations there was
admittedly a great deal OF uncertainty, az
well ms In the conclusions based uDOn them
assuming the observations Themselves to be
trustworthy The observers were no doubt,
ungousciousy biased In working up their
observations and drawing their conclusions
by the expectation of finding tho day of
Venus 10 be, like that OF Mars about tho
same length as the carth's. Yet II is easy
10 see that the aspect Of a planet parlicu-
larry If 1t presents no very stril,ipg features
viii be the same from night to night whether
the planet has made in the Intervening
twonty-iour hours 4 complete revolution on
its axis or has not rotated at all. That this
was tho true Interpretation to be put upon
these observations, namely, that they indi-
Gated that the planet MAS practically sta
tionarE on It's axis during the whole twenty
four hours, was the conclusion reached NV
S,hanarolli. as the result OF his own OBJ
Scfvaions, made between the months OF No
Nomber 1877, and February l'1S Like
bianchini. Schiapareli observed the dark
ish spots on tho planets disk which, faint
as they are for ordinary observers and under
ordinary conditions OF seeing he was able
to make ont, through the clear skies of Italy.
with sufficient dlstinc;nnss 10 feel certain of
their Identity Tho conclusion at which
Schiaparelli arrived was that the rotation
takes place in 225 days. which IN also the
period OF the planets revolution around the
sun Furthermore, he found that tho
planets axis Is very nearly perpendicular
10 The plane OF the ecliptc, not being in
clined TO it more than about - degrees al
though tho preceding observers had made its
inclination about ~ degrees.
A. this time Schiaparcll had not estah-
llshed his reputation as the most keen-eyed
OF living astrOnomurg-thCse observations
as well as his discovery Of the canals Of
Mars, made about the same time, were
made with a telescope Of eight inches
IN aperaturc-and astronomers We're not gem
orally tnclircd to accept conclusion which
seemed to separate Venus i'm so remarkable
a manner from her sister planets. In 1890.
however. his discovery was confirmed nv NJ
Perr0tin at Nice. VI. pcrrotin concluded
from his own observations that the period
OF the planets rotation did not differ more
than thirty days from it's slGercal period.
being cThere between 1915 and 925 daye
IiErDNpry to I.
rcc1nllFmed by the astronomers at Flag
stan.
Schiapareli's observations upon Mercury.
which led him to a like discovery rryardu,.
that planet, were made between the year,
ISL ana 1sS9-the most OF them in 1SB2-S3.
rms discovery is now confirmed for the
first time.
It would SEEM then. 10 be now fairly we'll
established that these two planets circle i'm
their ORBITS with one hemisphere turned
continually toward the sun. while the other
Is never iiumlncd by that body but 1,
involved IN perpetual night. Remarkable
as this state OF things is, it is not wholly
unaccountablc. and the fact that these
planets rcyoyc about lie sun m this ;yay
has moro direct intercs. for us-or. rather
for our very remote poslclity--than appcars
on IT'S lace, for IL Is n fate which the
mathematical astronomers declare will
sooner or later hcfall the earth. 1t is be-
lieyed to haTc been brought about by what
Is known rs the tidal action" Of the sun
SI'' HHlile S''i' OF utllDn Wnlcn, CNgrted by
tho earth apon the moon has so slowed
down the movement Of the moon upon Its
axis That 1t now rotate5 In tho Same limo
that 1t takes to circle its orbit around the
earth. This has been effected by the friction
OF the tides raised upon the moon by tho
carth's attraction In bygoEc ages either
while the moon was stil molten body or
whilo 1t still had oceans upon its surface
This action is reciprocal. The moon Is sun
posed to be still engaged In slowing down
the eartlrs rotation upon its axis by means
OF the tides, which 1t Is continually drag.
ging round me earth In direction from
east 10 west contrary to the earth's daily
mathematical astronomers, when the carth's
day will be month In length--.when II VIII
turn on It's axis with the moon as though
tho two bodies were bound together by
rigid bar of steel The sun as well ms the
moon raises tides upon the carth's rotation.
which must result in the end. II the end
Is far enough remote In time, in making the
day coincide with tho year az appears al
ready to have become the case upon Venus
ana Mercury.
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