The Idaho world. [volume] (Idaho City, Idaho Territory) 1864-1918, 1874-01-15
Written for the IDAHO WORLD. ]
THE TRANSIT OF VENUS.
BY ID. G. STRONG.

BY d. G. STRONG.
observed by young Horrox, an English Astron-
omer. Dec. 4. 1889. Two hundred and thirty
FIVE years ago. Two other transits June S,
176l. and June 3, 1869. have occurred since.
The fourth will take place Dec. 8, 1874. AL
ready the various governments of the civilized
world are fitting out large and expensive expe-
ditions of scholars and artists, to proceed to
those localities whence the observations can be
had, and watch, with care, this phenomenon
The nature and Importance of this occurrence
deserves some attention. If we look up into
the starry heavens on clear night, we see n
deep vault or back. ground Of blue. in which
the heavenly bodies seem to be- fixed, and the
whole revolving from east to west upon an I'M
aeinary axis, the northern extremity OF which
is situated 40 from what is familiarly known
as the pole star. Now, if we pass plane
through the centers of the earth and sun at
right-angles to this celestial axis, we will bisect
the celestial sphere, into Northern and South
ern hemispheres. The orbits OF all the planets
instead of lying in the place OF the echptic are
more or less inclined to it. The consequence
is. half the time they are on one side OF this
plane. and in their passage, cut it in opposite
parts of the heaven, these intersections are de-
nominated the nodes Of the planets. and line
connecting them is called the iine Of the nodes.
The nodes of the heavenly bodies are distribut-
ed around the ecliptc, but the nodes oi each
planet remain the same for all tine-thus, II
the node line of Venus be projected the ascend
ing node would be found to take place some
where in the constellation of Gemini-and the
descending sonewherein Sagittarus. and here,
and here only, this planet makes It's transit up
and down. To an observer on this modal line
outside, ot the planet the transit would be vlsi
bic every 235 days. The earth does pass either
| of these consultations every 800 days, nearly
Suppose now. Venus aud the earth on this line
af the same fime-th-re will then be n transit
of Venus This was the case Dee. 4, Io59
Having the periodic times al these planets, i
is easy to calculate hen they will again be II
the same relative position. Since the carli
masses these conscientious in the months q
December AMI June-thr transit OF Venus mus
always take place in one or the other ot these
mon,hs-ih, interval between two transits n
the same node is found to be either : or 23'
wears The reason Of this is that eight revolti
tions of the earth correspond very nearly 4
thirteen of Venus. but 235 Of the earth NOR
nearly I, 3s1 of Vcnus-at which time the.
will b. in very nearly the same relative posi-
,ion in the heavens, and consequently. \enu
will cross the suns dice every 2a5 days
The following shows the time for the iou
transits next to take place:
1s7i-December 8. 1S52-December d.
oOoi-June T. 2012-June D.
The Importance Of the transit of Venus he
in the fact that il furnishes the most reliaoI
data for determining the distance Of our cart
from the sun: and since this constitutes tn
!. base line of all our surveys of the heavenl
. b,dies. an error in this occasions similar error
: in all our tables
The following diagram will aid us IN "nde
standing the mathematical calculations base
uror this phenomenon: