The times. [volume] (Washington [D.C.]) 1897-1901, 1900-09-05
JUPITER STILL A MYSTERY.
Little Yet Known by Astronomers
About the Planet.

By far the largest and most perplexing
marking on Jupiter is the great red spot. ;"
| 1t is roughly estimated to be 30 600 miles
| long and 1900 miles wide. is pointed at
| both ends, and lies parallel with and Just
| south OF the southern equatorial dark belt.
! AS II by some mysterious power of repul-
| sion it has created a deep indentation in
the margin of the belt. SO that a wide
boundary Of brightness is interposed be-
tween the edge of the cavity and the spot
When the great red spot was discovered
in 1878, it had fairly we'll defined outline
and salmon pink hue. During the next
two years it gaineG in distinctness, and its
color deepened to hrick red. Then it be-
gan to fade. From that time to the pres
ent its visibility aBd tint have undergone
many fluctuations. At times tht. spot has
almost entirely disappeared. an then it
grows in distinctness. When Uear the
minimum of visibility it appears only as
a very faint ring of pink, the central por-
ton being white or grey. Tiere are per-
ceptibie differences, too, in the ease with
which the two ends can be distinguished.
In 1896! the spot almost completely dis
appeared. Stanley Williams we'll
known English amateur, reports in the
Observatory" for July that within the
last few months there has been a distinct
revival. Its color is now a salmon pink
and Is almost uniformly distributed, al
though the front end seems to be little
paier than the rear. Mr. Williams adds
that, whereas in 1898 the spot appeared to
have gained on the adjacent cavity In the
southern belt and to have fallen behind in
1899, il is now in about the normal posi-
ton.
Two or three years ago observers called
attention to the fact that the equatorial
bright zone possesse'i a rich orange yellow
no
white. In 1899 the southern dark belt had
deeper reddish hue than the northern.
but now the conditions are said to be re-
versed. The color VI Dotii is that of iron
rust Similar differences between, the two
Clark belts N the plentitude of small dark
or white spots. protuberances from the
edges. diagonal riffs and other minutiae
are observed from year to year, and it has
been suspected that there are variations in
the rotatioral velocity OF certain regions.
but on this point there is no agreement
among the authorities. 1t has also been
asserted that In these manifestations of
activity there i, periodieity like that in
the abundance and size of sunspots.
The nature OF the great red SPOT, which
is just now increasing in visibility is vet
mystery. Jupiter is believed to be in a
state half way between that of the earth
and the sun. Since It was detached from
the latter In the formative period of It's
history il has cooled down a great deal.
of course. yet it is PROBABLY still molten
mass. Partly because it is at only a red
heat and partly because il appears TO be
pretty we'll clothed in Clouds it is thought
that 1t has ceased to shine by its own
light.
Mr.. Maunder expressed the opinion a few
days ago that if the vapors that enyeIop
the planet could be swept away Jupiter
would exhibit a surface of Uniform red
ness like that of the big spot And Mr.
Barnard remarked in 1892. Just after a
temporary revival in distinctness, that the
phenomenon seemed to MIN to be a shifting
of an everything but very thin veil There
vas disposition fifteen or twenty years
ago to suppose that the spot was new
born continent lifted up above the levsl
Of the adjacent territory by some internal
force. But if. as Mr.. Williams thinks, the
spot shifts its position. that theory would
be untenable. On the other hand if one
imagines that ne is merely looking down
through a hole in the clouds, it will be
necessary, as Mr.. Maunder has pointed
out. to explain why that framework
mains so nearly stationary and so I'M
changeable in form. For the present the
problem is insOluble.