The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1882-11-15
The Transit of Venus Ina December
Next.

The relative distances apart Of the bodies
constituting our solar system are known.
but the actual distances are not. 1t is
known, for example, that the distance from
the sun TO the planet Mercury bears GER
tain proportion to the distance from Mcr-
curry to the earth, but for want Of an accu-
rately-measured unit applicable TO celestial
distances the distance apart in miles OF the
planets cannot be ascertained with prcci-
sion. The unit actually employed is the dis
lance from the earth TO the sun, which Is in
doubt by several millions OF miles. Natu-
rally, astronomers are much concerned to
correct the standard unit OF the heavens
TO the last attainable degree OF accu-
racy, and rs observations OF the transit
OF Venus across the suns face supply
means OF ascertaining, within half mil
lion OF miles, its true length, they look
with much interest to the transit TO occur
on the 9Th OF December next, after which
date none other will occur till June 8, 2004.
Transits of Venus usually occur in Paris.
the two transits OF pair being separated
by only eight years, but between the near
est translts Of consecutive pairs more than
n century elapscs. As the transit Of 2004
Is the first of a pair, there will be another
June 6, 2012. The immediate object in
view in making observations OF transits Is
to determine the solar paIallaX-that Is to
say. the difference OF position OF Venus on
the face OF the sun as seen simultaneously
by two observers occupying widely sepa-
rated stations. Observers on opposite sides
OF the earth would. during transit,
see at the same instant the planet as
a dark spot passing across the solar disc.
but it would not occupy the same position
20 both observers. This difference of posi-
tion is precisely what astronomers wish TO
measure, and, this being known, it will be
easy, with the known ratio OF the distance
between the earth and Venus, and Venus
and the sun, TO deduce the actual distance
from earth to sun. The phenomenon Of
the parallax, or something analogous to it,
is familiar one within every individuals
observation. Let the reader close one eye
and look at his finger held up between the
eye and any small object across the room
Now closing that eye and opening the othel
the object before looked at will appear f
have shifted its position. The degree L
which il appears to have changed its posi-
tion is the paraltaX. The solar parallaX, a
reckoned by Encke, is S.57 seconds. +. J
Stone in 1865 put it at S.9l seconds. TIL,
greater the distance of the sun the smaller
of course, it will be found TO be ProfesSo
G.. A. Young gives $50 seconds, which vii
indicate mean distance OF the sun from
the earth OF 92,SSJ,O00 miles. As the Inca
value OF one second applied to the -un's sur
face, as dcduccd from the parallaS given b.
Professor Young, is 1903 miles, the differ
ence of position of Venus dulings, transit
n seen by observers separated adiStanc
equal to half OF the diameter Of the earth
would amount TO 500 ca miles. TIE Unite,
States Government will have obSeryin,
stations 1T Washington at Fort Thorn
New Mexico; Cedar Keys, Florida: Sal
Antonio, Texas, Santiago de Chill: in New
Zealsnd; at Santa Cruz, Patagonia. and Il
the Cape of Good Hope. The Germal
Government has statiGls at Aiken, s. C.
Hartford, CcnH.; Bahia Blanca, Ar2eutia
Repubhc, and Pnta An mas, on the Strait
OF Magellan. Well-equipped obscrgatoric
Throughout E1repe will devote themselve
10 the transit. abe English and FTenc
governments win have stations abroad a
the Cape oS Good Hope, Ia. The Bernnidas
in Florida, The NVeat Indies, in the AEgeu
tine Republic, ii New Zealand. .an,
Australia, n.pt TO mention ,UnerouS sta
tions occupied by private p4rties.- BaYi
1sore Sun.