Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-06-08
Studying Stellar Bodies

urally with variability, for most of the
blinking stars are of enormous size.
Gradually, after Mira, other variables
were discovered. But by 1914 only Is
| were known, and in all the world there
were only five astronomers sufficiently
interested to watch them. Today some
1000 variable stars are catalogued and
reports total more than 10000 obServa-
lions annually.
Much credit for this modern recogni-
ton Of variableS must 60 to Prof. Ed
| ward G. Pickering, who early in his
| astronomical career gave attention to
these mysterious changelings. AS re-
suit of his interest which was made
especially effective through q photo
graphic patrol of the skies, more than
5000 Of the 1000 known variable stars
were discovered at Harvard. And they
have been most assiduously studied
there and followed through their fluc-
tuations year after year. Thus in 1911
Prof Pickering reported: During the
years 1906 to 1910 about 1900 observa-
tions have been made by astronomers
| connected with this observatory, of
which $4,000 have been made by Mr..
Leon Campbell"
Campbell Now Recording Officer.
It is interesting that this same Mr.
Campbell, whose prolific industry as an
observer came In for special mention
then, today is the recording officer Of
the Variable Star Observers. He is the
professional astronomer at Harvard to
whom the reports pour in from all over
the world. It is his job to supply OBJ
servers with celestial photographs and
the other data required for drawing
their star charts, to tabulate their re-
ports for publication, keep books on the
strange stellar mutations and supply re-
search astronomers throughout the
world with the annual harvest Of ANA
teur observations.
And why are the. researchers inter-
ested? Because variable stars more
and more are proving themselves to be
astronomical weathercocks to point
which way the cosmic winds are blow
ing. It was changes in Alg0 that aid
ed in the first measurement of the di-
ameter of a star. It was the study of
q group of variables in the small Mag
ellanic cloud that revealed the utility
Of Cepheid stars as indicators of dis
lance, and thus provided new yard
stick for plumbing the depths Of the
universe.
There are variables and variables-
short period, long period, or irregular
Those of short period, of which the
Cepheids constitute a select group, are
being studied intensively at large OBJ
servatories where there are powerful
telescopes and other instruments capa-
BILE of detecting and measuring their
rapid and slight changes.
The long-period stars-and the 1r-
regular ones, which are long-period,
too-are ideally adapted for amateur
study because of their more extended
time Of variation. Some require two
years to pass the cycle from brightness
to dimness and back again, though for
most OF them the period Is less than
a year. There are $50 of these long
period and irregular luminaries which
the American Association of Variable
Star Observers has accepted as its spe-
cial wards to keep night watch on.
The astronomical fellowship is scat
tered one. And it is to bring them to-
gether that these semi-annual meetings
are held. For while there will be for
midable astronomical reports and COM
4nittee assignments and much high dis
cussion in Maria Mitchelfs old home
stead next Saturday, the biggest reason
for getting together is "just for the fun
| of it."