The Charleston daily news. [volume] (Charleston, S.C.) 1865-1873, 1872-08-28
MOTIONS OF THE STARS.

From the Popular Science Monthly.]
1t seems utterly incredible that astro nomers
have learned not merely whether certain stars
are recedlng or approaching, but have actu-
ally been enabled to determine respecting this
kind OF motion whL they cannot determine
respecting the more obvious thwsrt motion
viz, the rate at which the motion takes place.
This Is rendered possible by what ls known of
the nature of light. II q star ls approaching,
the light which comes to us from 1t will have
Its waves closer together than If the star
were at rest, and vice uerSa. Now, the dis
tance between the wave-crests Of light slg-
nI6es difference OF color, the longer waves
producing red and orange light; waves OF
medium length, yellow aud green light; and
the shorter waves producing blue, indigo, and
violet light. So that II star were shining
with pure red light 1t might by approaching
very rapidly be- caused 10 appear yellow, or
even blue or indigo, according to the rate OF
approach, while If a star We're shining with
the pure indigo light 1t might by recediug
very rapidly be caused To appear green or
yellow, or even orange or red. But stars do
with mixture Of ali tSs coiors Of the rain.
bow, so that the attempt 10 estinate stars
rate of approach or recession by It's color
wou,d fail, even though We knew the
starss real color, and even though STARS
moved fast enough TO produce color-chaoges.
The spectroscoplst hus, however, mucn
more delicate means OF dealing with lhe mat
ter. The rainbow-Llnted sIreak forming a
star's spectrum ls crossed by known dark
lines. aad these serve a. verltable mile-marks
fur the speclroscopist. II one of these lines In
the speclrum OF any star is seen to be shifted
toward the red end the observer knows that
the star is recehDg, and that swlitlyi IL
the shift la toward the violet end, he Knows
that the STAR IL swiftly approaching. NOW,
Dr. HuppIus had been able nearly
fnur wears ago 10 apply this method 10 the case
of the bright star Sirius, though his lnsttu-
mental means were not then sutlcient 10 rem
der him quite certain as 10 the result sui ne
was able to announce, win some uegree vi
confidence, that Sirius Is recedlnS a. raIe
exceeding twenty miles per secoad. IN oraer
that he might extend The method to other
stars ihe Ro,sl Society placed ut Ills disposal
bne telescopp, fifteen inches In aperture,
and specially adapted 10 gather as much
Iirht as possible with that aperture. Suit
able specIroscopic appliances were also pro-
yIded for the delicate work DR.. Hng2lne
was to undertake. 1t was but last winter
that the instrument was ready LOT Work; out
already DR.. Huggns has obtained the most
wonderful news from the STARS Win us alo.
He finds that many of the stars are travelling
Tar more swiftly Than had been supposed.
Arcturus. for example, Is travelling toward us
at ihe rate OF some fifty miles per second,
and as his thwart motion is fully as great, Qor
this stars distance has been estiDated.) the
ac,nal velocity with which he Is speeding
through space cannot be less than seventy
miles per second. Other stars are moving
with corresponding Velocltles.