The sun., 1894-05-13

~n. Gee. T,-s 80 Lees :. Ars.-v-s.
rrn.-. Pr-iss wss SEES - SsA

", ,or ANYBODY to take the vsry slight
-. .eded 10 q nd Arcturus. for who would
.-..b 70 see what Is. perhaps. the greatest
.on.,i.ed In the visible unlYsrss1 SUP
80. s,sryoody knows the nGGrs OF the Dip
r.r" ia the SKY. At this seasen about @ p NJ
s,,s.rly overhead in the north. It's handle
,.,g,o the east andJts upturned bowl tot the
-, o,tbs m sridian. Follow the curve OF the
I..tl. 20 the snd and extend Il with similar
-~,.,r, for . distance somewhat exceeding
,hs ssn,ire length " the Dipper and you will
"a ,-.tr-us There IL not the slightest dan
.,ofinlsstnR or mistakinR IL. for there is no
,,aric that rart OF the SKY possessing ore
og,r,sr o. the brightness OF Areturus. soft
,.dat.h tinge Distinguishes its light from that
A. Ali OF its fainter neiRnbors. This reddish
hp. which believe to be variable. has pc
,uli.r .tsnidcanee. as We shall see.
rns stat.ment will be found in some Of the
ali .ehoobooks that Arcturus IL probably one
Al the nearest: OF the stars. AZ matter OF
,,.t i, 10 one OF the most remote Of thoes
-bo.s distance Is measurable. II must be sd-
nittsd that the few measures that have been
made are very diseordant. aud in what follows
lanai assume the correctness OF the results
oht.ln.d by DR.. Elkin. The measurement OF
,ha distance Of q star is . vsry beautiful
,rob,.n. and the tundamen principle 10
,.,,sctl IN sim pie II depends on the revelation
ot IN. earth aroupd the sun. On the LIST Of Jam
nary the earth Is about la. .OOo. 900 miles from
N. place IL will occupy on the 1st Of July. be-
s.us. on those two dates IL 10 At opposite points
a, ne orbit and the distance across the orbit IL
lsiOCO 900 miles. The diameter OF the earths
ortit thus serves the purpose OF surveyors
b.s. Inc Il 10 plain that the direction In
which q star Is seen cannot be exactly the
,sms from both ends OF that line unless the
.taY, distance IL so immense that the diam
.tsr of the earth's orbit bears no measure
shls ratio TO It, Most OF the stars are
40 distant that that ratio cannot be asesr-
tanned but there are = few whose ap-
parent places are appreciably different
when viewed from the extremitiss OF our
isiVU0 900 mile base hns. According 70 DR..
Elkin the position OF Arcturus Is thus shifted
TO the amount Of .o1S OF . second OF arc. and
thi, ts called its parallax. How exceedingly
delicate the methods en- ploy cd in measuring
,uch aluantity must be can. perhaps. be un-
dsrs:ood when II is stated that .01s Of second
o, arc 10 equal to the apparent distance be-
tween the heads OF two pins placed one inch
spart and viewed from distance OF 1SO milesl
Having ascsrtained the psrsllaI OF . star
the next step Il easy one Multiply the
earth's distance from the sun e3.OOO0O0
miles. By the number POD. .26S. which IL .
na,hs N stical constant that shall not here
undertake to explain. and divide the result By
the paral!ax OF the star. The auotlent will BE-
the stars distance in miles. II We apply
this rule In the case OF Arcturus We have
le.1s2.0+5. 900 900 .oes. 100 oso. 600 900
nilea In round numbers. one thousand mil
lions OF millions OF miles. or about IL. 100000
times the distance Of the sun from the earth
Tho reader may Iot down In his notebook the
number 100000. .ooo.o leaving OF the
less significant figures We have used above.
and IL will always enable him to ascertain the
Approximate distance In miles OF star whose
parallax II given. this number being used as .
dividend. and the psrallax. expressed In the
form Of q decimal fraction. as . divisor.
Now having found what Areturus's distance
IL. another simple calculation will enable Us
to compare the actual amount OF its light with
that Of the sun; in other words. to say how
much greater . sun than ours IL Is
Various estimates have been made from
time TO time Of the light which We receive
from certain Of the brightest stars eompare2
with that received from the sun It is proba-
big fairly accurate TO say that the sun sends
Us about IS. 600 oOo. 900 times - much light
as Arcrurus does; In other words. that it would
take twenty-five thousand million stars. as
bright ss Areturus.to make daylight on the
earth
But - everybody knows. the intensity Of
light decreases with increase OF distance. II
We were twice far away from the sun - We
are We should get only ons-auartsr - much
light from IL a. ws do II We were three time a.
far away We should get only on ninth - much
Light the Light varying inversely as the square
Of the distance. Situated where We are the
sun givss Us enormously more light than
Arcturus does: but We have Just seen how
snormo ously further away than the sun Arc
turus 10. Let Us suppose. then. that the earth
could be removed to point half way between
the sun and Arcturus. In that ease those two
shining bodies would be on equal terms 50
far ss distance was concerned Which, then.
would give the greater light to the earth ?
Areturus uaqusstionably. The real distance
Of Areturus is II. 400. 900 times the real dis
tAnes OF the sun: but at point half way be
tween them the suns distance would be 5. 70o.-
900 times greater that it now Is while Arc
turuss distance would be diminished one-hali |
But since light varies inversely as the square |
Of the distance increases. the suns light would
Be diminished the square Of ;. 100000. or 3D. |
40 900 900. 600. while that Of Areturus would |
be aGAdruplsd Now. glAneinE back We see that |
In the present position Of the earth the suns |
light exceeds Areturus's light in the ratio of |
$4,000 0Oo. 900 to one: but With the earth half |
waI ostwsen them the suns light has dimin- |
hAsd. as a result OF increased distance. b.
$4,000 900. 900 times, and Areturuss light |
has Increased. through decrease Of distance.
four tlmsS MultiDlYing together these two /
nunLers and dividing the product by 1900
ouUOOO We get 5. .l9S. whieh:is the number Of |
times thAt the light Of Areturus exceeds the
sun At an equal distance; so that Areturus Is
really As far as radiAting power goes. equal TO
Bliss such SUES as ours,
Does the neat Of Arcturus exceed that OF the
sun in the same ratiol Very likely IL does
II, then, We were near to that giant star a.
ss are TO The sun should be not only
eintst. but burned up. The frame OF the
earth itself would melt an ttiissolVs and burst
into cloud Of ferJ VaDoES II We suppose
hAtths Intensity Of the radiation Of ArctuFAs
b The SANE Gs that OF the sun. per unit % sur
lace, Arcturus must DO about seysntJ-tWo
unes as great IN diameter as the sun. and
STOUT $4,000 times as large in volume Its
eAne'er IN miles il. on that supPO-
G'!on, no less than 2.35O. OOo. Imagine
~ me llansts ol our solAr sIstsm L