The sun., 1890-07-13

Signor SCHIAPARELLI the italian astrono-
mer who has made more wonderful discov-
cries among the planets than all the other
astronomers of our day put together, has just
furnished now surprise, greater even than
his recent discovery that Mercury performs
only one rotation in the course OF revolu-
tion around the sun. He now asserts that
Venus. the brightest OF oil the planets that
| we see the twin sister OF the earth, which
is at present glowing with nightly increas-
ing splendor in the west after sundown, also
| turns but once on its axis In tho course Of a
revolution around the sun. In other words
there Is no alienation Of day and night on
Venus, as on the earth. The planet enjoys
perpetual day on one side of its globe, while
the other side is plunged In unendng night.
Astronomers have heretofore beloved that
the time Of Venus's axial rotation corre-
sponded almost exactly with that of the
earths, namely. twenty-four hours. This
was supposed to have been established by
noting the return Of spots visible on Venus
to similar position night after night; but
SCH1APARELLI shows that some Of these OBJ
servations have probably been misinterprct-
ed, and that Instead OF indicating q rota-
ton period oftwenty-four hours, they rather
| confirm his conclusion that the rotation Is
| performed In 224.7 days, which is the time
the planet takes to complete revolution
around the sun, or, in other words, Is the
length OF Venus's year. Venus is about 67,-
| 100000 miles from the sun, and its orbit Is
| more nearly q circle than that OF any other
planet. 1t follows that there is very little
variation in the amount OF solar heat falling
upon Venus at different periods OF its year.
! SCHIAPARELLI says the axis OF rotation is
nearly perpendicular to the plane of the
orbit. If that is so. Venus has no diversity OF
seasons such as the earth enjoys. It's equa-
tor forever burns with the ardent heat of AL
| unending summer, and its polar regions un-
| dergo no change OF temperature. Inasmuch
as Venus receives almost twice as much
light and heat from the sun, In consequence
OF its greater proximity, as the earth gets,
it must be pretty hot in the equatorial re-
gions on that side Of the planet which per-
petually faces the solar furnace.
If what the great italian observer says
about Venus's rotation is true, then the addi-
tional fact announced by him that the plan
cts axis is perpendicular to the plane OF its
orbit seems almost providential provision
of nature, for in that way 1t is rendered pos
plOlO AOI L1lO pOAoA ACklO4o W cIlJOy COu-
paratively mild climate, although the equa-
tor and the spaces corresponding to our
tropical and temperate zones may blaze with
uncomfortable heat. Ifthe axis OF Venus were
inclined like that Of the earth, the conse-
Quent variation Of seasons would plunge
the poles alternately into a day of fierce sun
shine enduring for seventeen weeks, and a
frosty night Of equal duration. The result
would be that life under such forms as 1t as
sumes upon our globe would probably
be impossible anywhere on the sur
face Of Venus, for the sunward
side OF the planet would be soorched
while the night side was frozen. But IT, as
SCHIAPARELLIs observations indicate the
poles Of Venus are not tipped now one and
now the other toward the sun, but remain
upright at right angles to the direction OF
the sun, then in their neighborhood the heat
may be tempered just as 1t is at the poles OF
the earth, in accordance with the law OF in
cidence OF the solar rays. or course the
cold. being unbroken, may be very intense
just around the poles themselves, and in fact
within few years past white spots have
been discerned on Venus, about where the
poles would be situated according to ScHIA-
PARELLTs idea; and these spots may be
caused by accumulations OF snow and Ice
there. But In somewhat lower latitudes an
agreeable mean might be found between the
consuming heat Of the equator and the gla-
cial chill Of the poles. The Imagination may
not go lar astray in picturing these inter-
mediate zones. on the sunward side of the
planet as the scene OF activities correspond
ing to those that mark the human occupa-
- kha lpI.
To be sure. the inhabitants OF even these
favored regions on Venus could not enjoy
the agreeable interchange OF day and night,
but would be perpetually shone upon by the
sun; but even here there are indications that
nature may have provided at least partial
compensation. All telescope observations
Of Venus testify to the binding brilliancy OF
its surface; and the most reasonable hypoth-
esis yet put forth to account for this phe-
nomenon is the existence Of an extraordl-
nary amount OF cloud in Its atmosphere.
Anybody who has watched sun-iIlumined
cloud knows how splendidly 1t reflects the
light; and. OF course In looking at the clouds
Of another planet We can practically see
only their sunny side.
II. then, as appearances indicate Venus's
atmosphere is largely filled with clouds, the
effect would be to screen Off the superabun-
dant sunshine, and perhaps render even per-
petual daylight far less obnoxious than we
might, at first sight. be- disposed to regard
1t There are reasons for thinking that tho
atmosphere OF Venus is most abundant. It's
depth has been calculated to exceed that OF
the earth by about one-thlrd, although
Venus Is slightly smaller planet than ours.
The existence OF watery vapnr in this at
mosphere has been clearly established by
spectroscoplc examinations OF the extent
or even the existence OF oceans on Venus we
know nothing by direct observation. but
since the planet possesses an atmosphere