A Journey in Other Worlds [79]
to some extent, with
previous records, a somewhat full abstract of them will be
useful: The object of general interest was the great red spot.
The outline, shape, and size of this remarkable object has
remained without material change from the year 1879, when it was
first observed here, until the present time. According to our
observations, during the whole of this period it has shown a
sharp and well-defined outline, and at no time has it coalesced
or been joined to any belt in its proximity, as has been alleged
by some observers. During the year 1885 the middle of the spot
was very much paler in colour than the margins, causing it to
appear as an elliptical ring. The ring form has continued up to
the present time. While the outline of the spot has remained
very constant, the colour has changed materially from year to
year. During the past three years (1884- '86) it has at times
been very faint, so as barely to be visible. The persistence of
this object for so many years leads me to infer that the formerly
accepted theory, that the phenomena seen on the surface of the
planet are atmospheric, is no longer tenable. The statement so
often made in text-books, that in the course of a few days or
months the whole aspect of the planet may be changed, is
obviously erroneous. The oval white spots on the southern
hemisphere of the planet, nine degrees south of the equator, have
been systematically observed at every opposition during the past
eight years. They are generally found in groups of three or
more, but are rather difficult to observe. The rotation period
deduced from them is nearly the same as from the great red spot.
These spots usually have a slow drift in longitude of about five
seconds daily in the direction of the planet's rotation, when
referred to the great red spot; corresponding to a rotation
period of twenty seconds less than the latter.'
"This shows," continued Bearwarden, "that as long ago as towards
the close of the nineteenth century the old idea that we saw
nothing but the clouds in Jupiter's atmosphere was beginning to
change; and also how closely the two English writers and Prof.
Hough were studying the subject, though their views did not
entirely agree. A white spot is merely a storm-centre passing
round and round the planet, the wind running a little ahead of
the surface, which accounts for its rapid rotation compared with
the red spot, which is a fixture. A critic may say we have no
such winds on earth; to which I reply, that winds on a planet of
Jupiter's size, with its rate of rotation--though it is
480,000,000 miles from the sun and the internal heat is so near
the surface--and with land and water arranged as they are, may
and indeed must be very different from those prevailing on earth,
the conditions producing and affecting them being so changed.
Though the storm-centre moves two hundred and sixty miles an
hour, the wind need not blow at that rate."
Later they saw several smaller spots drifting eastward, but
concluded that any seaworthy ship might pass safely through them,
for, though they were hurricanes of great violence, the waves
were small.
"There would be less danger," said Bearwarden, "of shipping seas
here than there is on earth; the principal risk to travellers
would be that of being blown from the deck. On account of the
air's weight in connection with its velocity, this would
necessitate some precaution."
The next object of interest was the great red spot. It proved,
as Cortlandt had predicted, to be a continent, with at that time
no special colour, though they easily recognized it by comparing
its outlines with those of the spot in the map. Its length, as
they already knew, was twenty-seven thousand miles, and its
breadth about eight thousand miles, so that it contained more
square miles than the entire surface of the earth, land and water
included.
"It is clear," said Cortlandt, "that at some season of Jupiter's
long year a change takes place that affects the colour of the
leaves--some
previous records, a somewhat full abstract of them will be
useful: The object of general interest was the great red spot.
The outline, shape, and size of this remarkable object has
remained without material change from the year 1879, when it was
first observed here, until the present time. According to our
observations, during the whole of this period it has shown a
sharp and well-defined outline, and at no time has it coalesced
or been joined to any belt in its proximity, as has been alleged
by some observers. During the year 1885 the middle of the spot
was very much paler in colour than the margins, causing it to
appear as an elliptical ring. The ring form has continued up to
the present time. While the outline of the spot has remained
very constant, the colour has changed materially from year to
year. During the past three years (1884- '86) it has at times
been very faint, so as barely to be visible. The persistence of
this object for so many years leads me to infer that the formerly
accepted theory, that the phenomena seen on the surface of the
planet are atmospheric, is no longer tenable. The statement so
often made in text-books, that in the course of a few days or
months the whole aspect of the planet may be changed, is
obviously erroneous. The oval white spots on the southern
hemisphere of the planet, nine degrees south of the equator, have
been systematically observed at every opposition during the past
eight years. They are generally found in groups of three or
more, but are rather difficult to observe. The rotation period
deduced from them is nearly the same as from the great red spot.
These spots usually have a slow drift in longitude of about five
seconds daily in the direction of the planet's rotation, when
referred to the great red spot; corresponding to a rotation
period of twenty seconds less than the latter.'
"This shows," continued Bearwarden, "that as long ago as towards
the close of the nineteenth century the old idea that we saw
nothing but the clouds in Jupiter's atmosphere was beginning to
change; and also how closely the two English writers and Prof.
Hough were studying the subject, though their views did not
entirely agree. A white spot is merely a storm-centre passing
round and round the planet, the wind running a little ahead of
the surface, which accounts for its rapid rotation compared with
the red spot, which is a fixture. A critic may say we have no
such winds on earth; to which I reply, that winds on a planet of
Jupiter's size, with its rate of rotation--though it is
480,000,000 miles from the sun and the internal heat is so near
the surface--and with land and water arranged as they are, may
and indeed must be very different from those prevailing on earth,
the conditions producing and affecting them being so changed.
Though the storm-centre moves two hundred and sixty miles an
hour, the wind need not blow at that rate."
Later they saw several smaller spots drifting eastward, but
concluded that any seaworthy ship might pass safely through them,
for, though they were hurricanes of great violence, the waves
were small.
"There would be less danger," said Bearwarden, "of shipping seas
here than there is on earth; the principal risk to travellers
would be that of being blown from the deck. On account of the
air's weight in connection with its velocity, this would
necessitate some precaution."
The next object of interest was the great red spot. It proved,
as Cortlandt had predicted, to be a continent, with at that time
no special colour, though they easily recognized it by comparing
its outlines with those of the spot in the map. Its length, as
they already knew, was twenty-seven thousand miles, and its
breadth about eight thousand miles, so that it contained more
square miles than the entire surface of the earth, land and water
included.
"It is clear," said Cortlandt, "that at some season of Jupiter's
long year a change takes place that affects the colour of the
leaves--some