Various bright and dark features appear in the polar regions of Venus from
time to time. The South Pole seems to be more susceptible to these phenomena
than the North Pole. These features are recorded right up to the present day
and remain largely unexplained. At times the polar regions of Venus are
brighter than the sunlit portion of the planet. Space probes have confirmed
the extremely high temperatures on Venus and we now know that the
polar
hoods cannot possibly be due to ice.
The polar regions receive less light than any other portion of the planet.
So what is the cause of this exceptional brightness? Scientists currently
claim that aerosols high in the atmosphere of the polar regions are the
cause. Why should the Venusian poles be so extremely variable in brightness?
And why is this phenomenon so random?
Apart from becoming especially bright the polar regions an disappear
altogether. Instead of the polar regions (cusps) ending in a sharp point as
one sees on the Moon, they can become “blunted” and rounded. The tips then
disappear altogether. On 28th December 1789, 31st January 1790, and 25th
December 1791, J. H. Schroter noticed the blunting of the southern cusp. He
also saw detached points of light beyond the blunted cusps. The southern
cusp of Venus is blunt more often than the northern one. This might indicate
that a southern hole is larger than a northern one.
In 1963 Dale Cruikshank wrote:
“Observers of Venus often note that one or
both cusps are abnormally bright compared to the remainder of the disk.
(Dr.) James Bartlett contributed a very worthwhile paper on his statistical
analysis of his own observations, those of Owen Ranck, and those of a group
of ALPO observers lumped together. For the present time we will call these
anomalous brightenings ‘cusp caps’, though this terms suggest a physical
interpretation that is unproved…”
One interesting fact that Dr. Bartlett
noted is that often (35% of the time) the cusp caps appear at both poles at
the same time. This suggests a common link. Why would the weather at both
extremes of the planet produce aerosols at the same time? What is the
connection between the two? The one connection could of course be through
the centre of the planet. Could it be that a certain excitation of a central
Sun could cause air to flow out of Inner Venus and to then simultaneously
create bright polar caps at the same time?
The Horns of Venus
South Pole
Both Venus and
Mercury go through Moon-like phases, as befits planets closer
to the Sun than the Earth. Venus, however, does not present the telescope
user with a uniform, mathematically precise phase. Sometimes the polar
regions (cusps) of Venus “extend” into areas where the Sun’s light cannot
possibly be falling. These extensions of the Venusian cusps are called the
“horns” of Venus. These horns are often much brighter than the rest of the
crescent. The horns may project farther than the laws of optics allow (i.e.
beyond 180 degrees at “Half-Moon” phase).
North Pole
Collars and Depressions
Sometimes a notch or indentation is seen just below either cusp. This notch
or indentation seems to be nothing more than the polar collar. However, when
it is seen in conjunction with the “horns”, it can give the horns a “hooked”
appearance. Patrick Moore, who disputes the existence of blunt cusps, has no
problem seeing the polar collar. He notes that he can only see it when the
polar caps are at their brightest. Moore has a tendency to write off many
phenomena as contrast effects. The real problem may be more complicated than
that. The collar might be more easily visible when the polar caps are
bright, simply because the bright background helps to highlight the dull
area around the polar Hole.
Perhaps the bright cusps are back-lit by light
from a central Sun? Perhaps this happen when the misty conditions inside the
planet clear up a little and more light manages to reach the upper polar
atmosphere? Perhaps the polar collar is also affected by winds blowing over
the edge of the hole as well? Such winds may raise dust and one might only
see this dust as it goes out over the rim of a hole.
The depression which many have seen over the past century may be related to
the blunted cusps. These phenomena seem to be very rare. It may be a long
time before a satellite captures a close-up image of it. What if the
depressions which astronomers saw on Venus are real? What if they really saw
depressions in the Venusian clouds. Why do I think that there may be a hole
underneath? Let us compare the planet to an orange.
Imagine the skin of the
orange to be its “atmosphere.” The Earth is 7,926 miles in diameter. 99% of
its atmosphere is contained in the first 30 miles of atmosphere. Now let us
scale this down to an orange 70 mm in diameter. Its atmosphere would then be
0.26 mm thick. The Earth’s aurora occurs at tremendous heights where there
is almost no atmosphere. The Earth’s aurora on such a little model would be
about 0.42 mm above the surface of the orange. An orange has a rougher
surface than a planet. The Reader should now appreciate how extremely thin a
planet’s atmosphere is.
The Venusian atmosphere is not much thicker than the
Earth’s. The planet’s atmosphere is akin to a thin “skin” covering the rocky
surface. Any depressions in that skin could never be observed from the Earth. Telescopes do not have that sort of resolving power to see
indentations so small. Nor could such depressions in the atmosphere dent or
deform the planet’s shape in any way whatsoever. 30, 50 or 70 miles is
utterly insignificant on a planet 7,700 miles in diameter. If such massive
depressions exist, then it can only be because the underlying crust is
itself deformed. Baum said that if the blunted cusp effect were real,
it surely indicates a tremendous drop in the height of the polar vortex.
And yet, if one looks at
those drawing one cannot help but doubt his reasoning. One is seeing
something so enormous – something far greater than a mere 30 or 50
miles. One can only be seeing an enormous dent in the crust of the
planet itself. In order to see something this enormous, and to have
the effect which it does can only mean one thing: the surface of the
planet has a dent in it hundreds of miles in depth. Such a dent
would be the deepest
crater or hole in the crust of any planet we know.
Astronomers have also seen streaks in the vicinity of the Venusian poles.
“From a close study of these surprising features
Baum drew certain
conclusions. The observed spots, especially the straight streaks, are not
superficial but permanent features as are certain polar features, notably
the dark band around the southern cusp cap. (Baum, like Lowell, regards the
south cusp cap as marking the actual pole); and from his study of the streak
system he considered that the rotation is very slow… He further considered
that the central spot from which the streaks radiated represents ‘an
enormous column of hot air’ rising from the sub-solar point and drawing into
it currents of colder air from all quarters of the disc, thus agreeing with
the conclusions reached by Lowell…”
Since the polar collar lies at the same latitude and remains in the same
position, it might be the result of a physical feature. The Venusian
atmosphere possibly rises and falls, and hence this polar collar may become
more visible when the atmosphere falls in height. If winds blow into and out
of Venus, it may be possible that dust storms add to the collar’s darkening.
It is hard to determine whether the collar is the rim of a hole which we are
seeing directly, or whether it is caused by turbulence from air going into
and out of a hole. But either way, the polar collar does lead to the
suggestion that we are seeing a physical hole beneath the polar clouds.
The Maedler Phenomenon
In 1978 Richard Baum wrote:
“One of the strangest observations ever recorded
of Venus was made by the renowned German astronomer Johann Heinrich Maedler
with a four-inch refracting telescope on April 7, 1833. At the time Venus
stood east of the Sun and was well placed for observation. In his Beitrage
(1841) Maedler tells us how on that evening numerous brushes of light were
seen to emanate from the illuminated limb of the planet, then a crescent,
and to diverge in a sunward direction… The brushes pointed towards the
fan-shaped, and invested Venus with the look of a broad multi-tailed comet…”
What could possibly account for this? …light from inside
Venus could have
caused this phenomenon. Maedler saw the light pointing sunward. This is the
opposite of what happens to a comet. A comet’s tail is directed away from
the Sun by the solar wind. Clearly, this explanation will not work for what
Maedler saw. His phenomenon could only have been caused if an Inner Sun was
quite a distance off-centre in the direction away from the Sun. Light from
an Inner Sun would then shine out through both Polar Holes at an angle,
pointing towards the Sun.
The light would be refracted by the hot, dense
atmosphere, and there would be a fan pointing towards the Sun from both
Polar Holes. Why hasn’t this happened again? Why doesn’t this happen more
often? In order for us to see this light it must be reflected off something.
When the light is refracted, it might often appear to us as a large oval
spot when it is not centered on a pole. We might see the oval because the
light is being reflected by atmospheric particles. We would never see the
light out in space because there is nothing for it to reflect off.