Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1858-12-23
Written fer the Green Mountain Freeman.
Astronomy--No. 6.

Written for the Green Mountain Freeman.
Astronomy---No. 6.
LATITUDE, LONGITUDE AND MOTION OF THE HEAVEN
LY BODIES.
From a casual observation of the starry
heavens, we should be led to suppose that the
stars had but one apparent motion, that from
east to west in twenty four hours, caused by the
real motion of the earth on its own axis, but on
closer attention we perceive another movement
in the starry armament SO small as scarcely to
be diDtinguishable in ou& day, but which, ina
week, presents sensible alteration in the posi-
tion Of the heavenly bodies. As a correct
knowledge of the apparent motion of the stars
is indispensable to any great advancement in
this branch of the science of astronomy, we
shall be pardoned for making the explanation
of them the subject of short article.
The most natural supposition Of the unlearned
would be that each constellation came to the
meridian at the same time every day, that is,
that each had its particular time for culmnat
ing and, like the sun, accomplished its daily
round in twenty-tour hours. Consequently,
they would suppose that if any star was to be
found on the meridian at nine o'clock in the
evening on certain day. it could be seen at the
same place and time throughout the year. Now
it is true that every star in the heavens come to
the meridian al nine o'clock in the evening, some
time during the yer, consequently, if any per-
son should uieU the meridian Of the heaUens
at nine o'clock for three hundred and and
sirty-fue Evenings in succession they oould
see every star Uisibe in the latitude Dhere the OBJ
seruation Dere taken. The same is true of any
other hour of the day and night.
This apparent motion of the stars is caused
by the motion of the earth in its orbit round
the sun, in manner which we will endeavor
briefly to explain. The earths orbit, like all
other circles, is supposed to be divided into three
hundred and sixty deg, and as the earth is
about three hundred and sixty6ve days in pas
sing round it, it is evident that it passes over an
area of about one deg in twenty-four hours.
Now if "a star as seen from the earth on a cer-
tain day, is situated deg east of the sun, it
: is evident that in twenty-four hours, the earth
having passed one deg. westerly, it would be
exactly opposite the sun, and consequently in
visible.
BY the same reasoning it is plain that on the
next day the same star might be seen one deg
s,est Of the sur, and in si1 mogths, the earth
having advanced to that point of its orbit be-
tween the sun and star, it would be exactly op-
poste the sun, rising just at sunset.
To illustrate: supposing that on the first day
should notice particular star at that time ex-
actly on the meridian at nine o'clock in the
evening; on observing it again the next eve
ming at precisely the same time, he will notice
that it has advanced past the meridian dis
tance SO small as not to be noticeable Aftel
the lapse of a week let him again view the sam'
star at precisely the same time it was first seel
on the meridian, and he will find that it ha
passed the eliminating point seven degrees
Now let him observe its motion for two or thre
months and he will find it to pass westerly un
til it has reached the same longitude as the sun
when it will rise and set with that luminary, re
naming visible for few days, when it ma
again be seen just before sunrise, a few degree
west of the sun.
Six months from the time the observation frs
commenced, the earth having passed half tn
circumference of its orbit, the same star wi
,1Do,x i tha frs
of December, or at nine o'clock, A. NJ, whe
), it will, OF course, be invisible. As the cart
passes around between the star and the sun, til
former will rise earlier each day, until finall.
>, on the first of December 1882 it will again
r, seen on the meridian at nine in the evening
r having apparently accomplished one revolutio
more than the sun in the same time.
:. As the whole circumference of the heavens
divided into three hundred and sixty deg ar
+ the stars by their apparent yearly motion pa
over the whole circle in twelve months it
- plain that in one month they will accomplish
g distance equal to thirty degs Now as by the
1T daily motion they accomplish whole revolutiC
in twenty four hours. in one hour they will a
ID complish one nty-fourth part of the who
distance or fifteen degs., and in two hours th'
4 will move over the same distance that by the
ID yearly motion they do IN month.
lg Consequently if we know what consolidate
OF comes to the meridian this evening at nine c
i'll clock, we can tell the exact time at which
In will culminate every day in the year, for it
evident that one month hence it will reach t
meridian two hours earlier than now, in ty
months four hours earlier, and so on throu,
ne the year.
,ir Having now explained the principal motto
IT. of the heavenly bodies, we will give the read
,c. few directions concerning the latitude a
ma longitude of the heavens, for which, in order
IS; facilitate the study of this science, imagina
.e1 circles have been considered as drawn in I
m. heavens, most of which correspond to and are
"a the same plan with similar circles, supposed,
ar similar purposes, to be drawn on the surface
u.s. the earth. The Axis of the earth we find
all Political Biographies to be an imaginary Ii
,ys extending through its centre north and soul
gs, about which its diurnal revolution is perform'
IS; An extension of this line both ways to the cC
m. cave surface of the heavens, forms the ATis
eed the Heavens; around which all the HEAVIER
the bedes seem to revolve, from east to west, OIL
g, in twenty-four hours. The extremities of &
md axis form the Poles of the Heavens.
on, The north star, which we have already poi
es- ed out, is situated about one degree and h
- . ~ a.4L .,oIo ,o +ho+ e;do which ;s on,