Bright Polar Caps and Blunt Cusps

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 airrising 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.