The Jackson standard. [volume] (Jackson C.H., Ohio) 1847-1888, 1877-05-17
WHOLE NO. 1861.
fFrom the scientific Amureaul
Light and the Distances Of the Stars.


A correspondent writes aa follows;
One Of the New York daily papers
gives an account OF a recent lecture de-
liyered by a Professor Grant on astfono-
my. 10 Great Britain. and reports him 10
have said that some stars are % distant
from the earth that light. travelling AZ
the rate Of lS5 COO miles q second. would
take half a million of years 20 reach ua.
anu that consequently We would Observe
now what bad transpired on such stars
halt n million years ago. ]. not this last
statement entirely erroneou.9 Does not
the eye travel almost instantaneously
along The line Of direction OF any object
I within the range of either unassisted hu.
man or trl~scopie vision. aud do We not
accordingly see what - transpirins now
at any point within such ranFv7 Please
state whether this view or that imputed
To Professor Giant ir cofrrct
To point out the error in our cores
pnnd~nt's reasoning. We have only To- APP
l'ly u 10 the propagation oi nnund and 10
the ear. aud then W. mHy ak. almust In
the same word. Does not the ear
travel almost instantau~ously along the
line Of direction of any sounding ohirct
within the range OF either unassi-tsd or
a-sisted human hearing. and do we not
accordingly hear what y tran-piFing nov
~ any given point within such rans~Y
We mHy ak this with good reason. be-
cause the naiur,s OF the propagation OF
light sud sound arr identical the eye
being the organ Tor the PERCEPTION Of the
hrst. the ear that Tor the PERCEPTION of
the second. Now the tact ta that the
eye Tor the sirhi) travels 80 little toward
the. iuminou. Object .. the ear Tor tho
hearing) travels toward the sounding Oh
jet, bath org-ns merely rso~ivs imprrs-
stone from the luminous or sonorous
rays. lt is perfectly we'll established
that We see astronomical events later
than they occur. aud 10 was this fact
which taught us that light moves with
velocity OF $4,000 miles per second.
The eclipses of the moons OF Jupiter 70.
vealcd 70 Roemer. the crlsbfatsd Ger.
man astronomer. this fact. be found an
irregularity which no astronomical data
could account for. aud be observed that
the periods between these cclipses we're
longer when the distance between us aud
the planet was increasing. Shile. inverse
~. the periods became shorter when this
distance was diminishing lie found at
last. by close observation. that every
time that the planet vas. say 100000 600
miles further of. We see that eclipsss
happen nine minutes later than they do
y ben the planet y at lie nearest die
lance. A. nine minute. is $40 seconds.
~ have only % divide $40 into 100000.
40 60 find the velocity of light per sec
ond. which 10 very nearly lHj.Uu0 miles.
III hi- has been vsrth~d aitsrward IN vari-
"a. other ways, the velocity Of light has
been directly measured 10y the help Of
most ingenious aud delicate apparatus)
by Fuucault aud Fresnei. while the ab.
erration Of the hKrd stars. which con.
.ista IN an apparent displacement oi the
same. produced Is the yearly motion Of
the earth its orbit. fully corroborat-a
the scientific theory. IL b. therefore.
positive fact that wc scs the stars as they
we're at the time when the light which
reaches us now left them; aud we see
the sun ~ be Was s minutes ago. tho
nearest fixed star ~ u was "a yeaFs aFo.
and the pole star as u was % years aFo.
Dl the other starr, very tew are near
enough for us TO measure their distances.
bat most Of them are thousands Of times
further uf and therefore we sec them aa
they were thousands Of years ago. and
when ihr t'.l--cnpr reveals. iu the d~pihs
Di tnhuitr spsrp. stars thousands ui thou
.aud t.mrs further of still ws arr con.
yincsd that Hs their ltght can only reach
us in millions Of years. We see them hs
they we're millions OF years afo. Pet.
hsps ~ that remote period. In those un.
distancrs. blaming suns have
lss~n crrntrd Of which thr light has not
yst reached "a. aud invsrsrly those may
have. become extinct oi which the light
reaches "a nov; in the same way aa
Nhrn ih~ sound Of sun. exploding at
sf.at distance. reachss us. the real Ok.
,. ision isa thing oi the past aud may
have taken place 50. 60. or more seconds
briurr, according ~ the distance.