The Atlanta constitution. [volume] (Atlanta, Ga.) 1885-19??, 1892-02-23
SEEN IN THE HEAVENS.
RECENT DISCOTERIES At THE LICK
OBSERVATORY
BY Edward S. Holden, Director-The Satei-
ties of Jupiter and Their Rotation Pc
riods-Somethins of Hercules.
Copyright 1892.
TUE"
Tho Satellites of Jupiter.


have been asked to give some account OF
recent investigation at tho Lick observatory.
The most generally interesting results recently
reached are those relating to the motions OF
the first and third satellites of Jupiter de-
duced by Professors Schaeberle and Campbell
from their observations of the past summer
with the great telescope.
The observations show that the first satellite
of Jupiter (the satellite nearest to the planeD,
is Of an ellipsoidal shape with its longer axis
constantly directed to the planets center,
while all the other satellites are essentially
spherical in form. The ellipsoidal shape may
very likely be caused by the immense tidal
forces exerted by Jupiter on its nearest attend
ant. The fact that the longest axis is always
directed toward the planets center shows that
this satellite revolves once about the primary in
the same time that it revolyes once on its own
axis The Same fact has also been shown by tho
same observers for the third satellite, though
in a very different way. long series OF draw
ings of the faint markings which are some
times visible on the very minute disc OF the
satellite has been secured and comparison OF
these drawings has shown that the third satei-
lite also constantly turns one face toward Jn-
p:ter, lust as our own moon constantly turns
one face toward tho earth. Such condition
of things in the system of Jupiter has long
been suspected ION more or less sufficient tes'i-
mony), but it is now established 1of the hrsV
time.
Markings have been seen on the other satei-
ltes also, but not sufficiently we'll prove that
they arc subject to the same law. The planet
is coming into a more favorable situation
wear by year. and it is very likely that 1t may
be possible to establish this law by actual OBJ
servation for each one of tho satellites Sepa-
rately. These results are of material imp0r-
lance in the theory of such bodies, and they
throw much light on the question OF tho age OF
the system of Jupiter. This is not the place
to do moro than announce the results OF OBJ
servation. Readers who carefor more detail are
referred to papers by Professors Schaeberlo
and Campbell in the publications of the Astro-
nomcal Society of the Pacific (No. 49,
The Cluster in Hercules.
During 1890 and 1891 this globular cluster Of
stars has been photographed several times With
the great telescope, with exposure varying from
seventeen to 10 minutes. 1t is impossible to
give representation of The cluster in this
place and a verbal description must suffice.
The cluster has long been known as one of the
most beautiful OF the g,obuar groups of stars.
1t is composed OF n mass Of very minute stars
closely packed together with outlying wisps
of stars on its borders. 1t is n beautiful OBJ
icct even in small telescopes, but it requires q
large telescope to show its manifold details.
One of its very remarkable features is a sys-
tenn OF three dark channels which meet ut a
point and form angles OF about 12O degrees
with each other, thus: