Evening star., 1925-10-11
OF HEAVENS.
STAR CATALOGUE, NEARLY READY
Astronomers Busy for Years Measuring Radial We
locities of Stellar Bodies to Determine Path and
Speed Our Sun Is Travelling Through Space.

2,6OO in all, has been but a means
to an end. 20 find out how fast and
in what direction the sun. with the
earth and she rest of the solar sys-
tenn. is moving through space: For
many Years 1t has been known that
the sun is moving toward a point
near the bright star Vega. in the con
Stellatlon of LJra. At first it might
seem herd 20 see the relationship be.
tween the promiscuous motions Of the
stars and the path Of the sun. but
1t is not SO difficult as it seems. If
the stars are moving in all possible
directions and We measure the!,
Telocities. there should be just as
many moving one way as another in
all parts Of the sky. provided the
earth is standing still. But If the
sun and the earth with it is itself
moving rapidly in d certain direction.
most Of the stars in the direction we
are going will seem to be APPROACH
ing. while the greater number Of stars
in the direction from which we come
will seem to be receding. In this
way, Or. Moore has found that the
sun is moving through space with the
speed OF about IL miles per second
Heavenly Twins Listed.
Nor has this been the only appli-
cation Of the measures OF the stellar
spectra. as over a thousand spectre
scopic binary stars. or doubles
have been found from the plates
These are pairs of stars that ,revolve
around each other, but are so close
that even the highest powers of the
telescope do not reveal their duplic-
ity. The spectroscope does, however,
Tor when one member of the pair is
moving from us the lines are dis
placed in one direction. At the same
time the other member is moving to-
ward US. and it displaces the lines in
the other direction, the result being
that the lines appear as double when
the line joining the stars is at right
angles to a line to the earth. When
the two stars are in line with us
the spectrum lines appear single, and
from the alienation of single and
double lines the time the stars REQUIRE
TO revolve around each other may be
determined.
Nearly 5000 Discovered.
However, not all binary stars are
observation-disclosures are far enough
apart to be seen as double with the
telescope. and It Is these that DR..
II. G.. Aitken. associate director, who
Is in charge Of the observatory In thu
absence Of DR.. Campbell, is studying
and measuring with the 3S-inch tele-
scope.
8. W. Burnham, at one time with
tho Lick Observatory and later at the
Yerkes. Observatory. was one Of the
first to catalogue these stellar twins,
and upon his death, his papers and
books were turned over to the late
DR.. Eric Dooiittie of the University
Of Pennsylvania as the leadins
authority then on the subject. When
Prof. -Doohttle died. Burnhan1's re-
suits, az well as his own, were given
to DR.. Aitken, who Is now engaEed in
an extension to Burnham's catalogue,
which will be published by the OBJ
servatory within q year The i'm
portance OF these doubles is shown
by the fact that star out of Is
in the sky can be seen as double with
the 36.inch telescope. Altogether
this observatory has been responsible
for the discovery Of nearly 5000 OF
them.