The morning call., 1891-08-31

power that can be well used during the
present apposltion will be seven hundred
diameters; but let HE give word OF caution
here to those who may Imagine that BY Wis
lting Mt hamilton on sufficiently good
night they would be shown
JUPITER
With such power. 1t is true that II they
particularly asked for that power their re-
quest would be granted, for there are no
more obllging and gentlemanly men OH the
face Of the earth than the astronomers at
the Lick Observatory; but what | wish to
say is that the power that would be put in
for the entertainment of visitors, unless
special reQues. for another was made.
would be the lowest power Ghree hundred
dIameters) no matter how good the see
ing" The reason for this is that there
is pleasing fiction maintained by
astronomers chat is, 1t is pleas
ing to themselves) that no one unused to
looking through telescope can see as much
in one as trained astronomer, whereas the
reverse is very often tho truth, provided
only the observers attention be directed In
the right way. For instance, l was able
from the very start to see six of Saturn's
satellites with the six-inch equatorial OF the
students observatory at Berkeley, While
IN the University of California, and trained
astronomer, can only see four. Yet the
telescope in question is strictly flrst-class
one, and the satellites are not very difficult
objects to my eve. In order, therefore, TO
main tain this fiction astronomers are IN the
habit of only letting visitors look with very
low powers with which they could not see
very much no matter what their eyesight.
But there Is another way for person
interested in astronomy to study planetary
detail than by looking through telescope,
and that is by carefully examining drawings
made by astronomers. In them we have
spread out before us all that trained
astronomer could see, and whose eyesght,
however weak, was helped by the fact that
he knew just what 10 look for. Furthermore
we can look just as long as we please, and
many of the drawings were made on very
fine nights which cannot be had for the ask
Ing. i cannot do better than advise anyone
who is interested in this matter, and who
has friend that is member of the Astro-
nomical Society of the Pacific, or who has
access TO the U. G. Library, to borrow
copies of those publications of the Astro-.
nomical Society which contain drawings of
Jupiter and to carefully look them over.
One series made by Mr.. Keeler with the
great telescope is very fine. Another series,
by Mr.. Barnard with five and 0ne-half
inch telescope. is exceedingly interesting,
especially the drawings made in 1880, which
show surprising amount of detail, much
more, in fact, than
CAN BE SEEN THIS YEAR
With six-inch telescope.
THE satellites of Jupiter are very fascin-
atiDg objects to observe as they continually
pass and repass before or behind the
planet. Their phenomena are occultatiOns
or disappearance behind the planet; re-
appearances from occultations; eelIpSes or
disappearances In the laneTs shadow,
which stretches out behind him for Sc. 100000
miles; their transits across his disc, and
the transhs of their shadows. These last
are quite beautiful and easy to see, the
shadow appearing as a round bla ck dot.
which slides rapidly across the.disc. Some
times TWO shadows are on the disc at once
The transitS Of the satellites themselves are
much more difficult to see, especially those
of the first satellite. In July this year l
examined the planet with the siX-inch re-
tractor of the students observatory at
Berkeley. and on night very nearly, II not
quite, as fine as | have ever seen either
there or at Mount Hamilton. looked par
ticularly for the first satellite, while it was
transltlng but 1t was quite invisible until
its edge began to project OFF the planet.
have no doubt that, had the planet be en- at
an altitude OF co. or 70' instead of 40,
could have seen the satellite.
LAS so much has been written and said
about the great red spot, will pass 1t by,
merely saying that ii is rather palmer this
year than for while past and is easily OBJ
servable with siX-inch telescope. The
adjective red is certainly miSnomer
now, the red color of the dark equatorial
belts being much more pronounced; its real
color is pink.
"a word more as to the best time to visit
course the best time should be about Sep
tember 9th, as the planet will then be at
opposition; but at that time he will not
cross the meridian until midnight, and so
cannot be seen to any advantage at ali early
in the evening about s in the evening"
when visitors do their looking through the
great telescope. The best nights, therefore,
will be those of October oath and 31st, par
ticularly the latter. Jupiter being on the
meridian about i'll the evening. OF course
if the night was bad one satisfactory
view could not be had; but it is during the
summer and fall that the best astro-
nOmical weather is experienced at the Lick
Observatory. Even with a power of 800
Jupiter would present most beautiful and
interesting sight in the great telescope, for
his disc is large enough to take in Saturn
and all his rings. l would also advise any
one going to the observatory especially to
see Jupiter to ask to see him through the
twelye-inch and siX-inch telescopes also,
for only by so doing could they get an ade-
quate idea of the superiority OF the great
telescope over all smaller ones. l am more
or less acquainted with astronomers and
have no doubt they would be perfectly will
ing to grant such a request provided the
work of the observatory permitted.p