Scientia Press

Immanuel Velikovsky argued famously, based on his interpretation of ancient sources, that Venus had emerged from Jupiter as a comet, interacted with the Earth and Mars in the second and first millennia B.C., and then finally settled into a nearly circular orbit of the Sun.

Here are three new lines of reasoning that tend to support this theory:

      1.  Instead of the various unpersuasive suggestions that Velikovsky and others have proposed for how a cometary Venus could have emerged from Jupiter, we should consider the possible consequences of the immense gravitational field of Jupiter, which pulls into the giant planet a stream of asteroids and comets such as Shoemaker-Levy 9 in 1994. 

A plausible scenario would have a dark, cold proto-Venus, coming from the outer solar system and invisible to observers from Earth, impacting the periphery of Jupiter, then managing to exit from the other side of the gaseous planet.  We can term this the Peripheral Passage (PP)  of Venus through Jupiter, and we can assume that the impact released a great deal of light that would have been visible to observers on Earth. This could account for the curious stories of the ancient Greeks, that Athena (Venus--eventually Aphrodite replaced Athena in this role) was born from the head of Zeus (Jupiter), and of the ancient Hindus, that Shukra (Venus) emerged from the mouth of Shiva (Guru or Jupiter).

A calculation of the relative areas of the ring defined by the outermost 10 percent of the radius of Jupiter and that defined by the innermost 10 percent reveals that the outermost area is 19 times as large as the innermost one.  This means that a proto-Venus could have impacted near the periphery of Jupiter and therefore in an area where the gas/liquid hydrogen (Jupiter has no surface; under increasing pressure, the atmosphere blends into liquid hydrogen) was much thinner, the distance to emergence on the other side considerably shorter, and the gravitational pull of the core smaller.  If a proto-Venus impacted in the outermost 10 percent ring at a speed somewhat faster than 59 km per second--the impact speed of Shoemaker-Levy 9--then it could very conceivably have emerged soon thereafter from the other side, glowing and at a speed above the 59.5 km/s escape velocity.  Or it could simply have grazed the giant planet.  Other factors could have affected its speed, including Jupiter's equatorial rotational velocity of 12.6 km/s and low density (1/4 of the Earth's). 

This proto-Venus would have been large and dense enough to maintain its integrity in the gravitational, magnetic, and thermal environment of Jupiter, though its surface would melt and some would be shorn off and become its giant tail.  This Venus would therefore possess a set of elements different from those of Jupiter itself.  And its momentum upon impact would permit it to achieve PP without generating immense new heat during acceleration from zero and thus risk meltdown. This scenario would also resolve the paradox that Venus is old (the proto-Venus) and yet its surface features appear young (shaped by its experiences after the moment of impact into Jupiter).  A similar pattern may be associated with Jupiter's moon Ganymede, whose surface and interior were remodeled by intense heat, presumably from its own PP of Jupiter--but Ganymede lacked sufficient velocity to escape from Jupiter's gravity and so ended up orbiting the gas giant.

The Peripheral Passage explanation would overcome the three chief objections--escape velocity, elemental composition, and heat generation--to the assertion of Velikovsky that Venus emerged as a comet from Jupiter.  The issue of the Jovian origin of Venus has been one of the main criticisms of Velikovsky's theories in general (it was #1 on astronomer Carl Sagan's list) as well as a key reason for denying validity to ancient accounts, many in mythic form, as sources of astronomical, climatic, and geological information.  These objections held particular importance because the whole theory depended on the reported emergence of a comet-like Venus from Jupiter, which seemed outlandish and not credible to critics.  Now that this emergence can be seen to have a commonsensical, scientifically plausible explanation, the credibility of the ancient observers--who after all were eyewitnesses--must rise accordingly, and therefore their other stories must be examined more carefully as potential sources of important information.   

          2. It is possible that the Black Drop (see 2004 photo below) observed during the transits of Venus across the solar disk is in fact the residual tail of the comet/planet. On ingress from the solar limb, the Black Drop stretches out behind Venus; on egress, it appears in front of the planet. During transit, it is not visible. A residual comet's tail on Venus could be shifted by the solar wind from trailing the planet at ingress, to standing away from the sun during transit (thus only the disk of Venus would appear), and finally to preceding the planet at egress.

The Black Drop is usually ascribed to various optical effects. One 18th-century observer said it made the planet look "like a nine pin". Drawings by observers make the Black Drop appear exactly like a small tail. The effect was originally thought to be related to the atmosphere of Venus, but the Black Drop was subsequently found to be too large. Mercury, which has no atmosphere, also has a Black Drop when transiting the sun; and it is clearly visible from a space-based telescope, so this effect is not an artifact of the Earth's atmosphere. This suggests that either the Black Drops of both planets are caused by some extra-atmospheric optical effect or that both planets possess remnants of comet tails. Presumably, the motion of the planet would make the tail (Black Drop) shorter at egress than at ingress, which could be measured; it is possible that skewing of the tail could be detected in transits that cut very obliquely across the Sun; and there might be some way to detect the tail as it stands away from the surface of the planet during transit. Or a sensitive telescope might detect a residual tail even when Venus is not transiting the Sun.

A recent explanation based on a Mercury transit observed from an Earth-orbiting telescope is that the effect is caused by the combination of the point-spread function of the telescope and "solar limb darkening".[1]

According to the comet tail hypothesis, the solar limb darkening is not a cause of the Black Drop but an effect of the residual comet tail. 

In 2012 Venus will transit the Sun for the last time in this century, affording an important opportunity to study the Black Drop to determine whether it actually constitutes a mini-tail of the sort associated with comets.  In addition, investigating the chemical composition of the Black Drop, if indeed it exists in the form of a mini-tail, could show whether its chemistry differs from the carbon dioxide and sulfurous content of Venus's atmosphere--and whether it contains hydrocarbons or other elements found in Jupiter. 

Findings from an investigation of the Black Drop may also help resolve the question of the Ashen Light, faint luminescence on the night side of Venus first reported in 1643.  Since the Ashen Light appears in roughly the same location opposite the incoming solar wind as would a comet tail, it may be caused by chemical reactions within a residual tail of Venus.  Presumably the strong glare of the solar orb prevents us from seeing the Ashen Light during transit by making the Black Drop appear blacker than it would otherwise be.  Both the Black Drop and the Ashen Light appear to have become harder to detect over the years since the early telescope astronomers spotted them.  This would be consistent with the diminution over several centuries of a residual comet tail. 

          3.  Lastly, a new interpretation of iconographic evidence also deserves attention. [2]  In the photograph below from Abu Simbel of Pharaoh Ramses II and his consort Nefertari appear what look like the comet Venus and its two-pronged tail in Nefertari's headdress, and the smaller Mars with its two imperfectly round moons and its own tail, presumably borrowed from Venus during an encounter with it, in the headdress of Ramses II. 

What is the age of this sculpture?  How could the ancient Egyptians have seen the moons of Mars with the naked eye?  How could these headdresses be explained other than as depictions of Venus and Mars during approaches to the Earth? [3]

 Notes

1.  Jay M. Pasachoff, Glenn Schneider, and Leon Golub. The black-drop effect explained. In: D.W. Kurtz, ed. Transits of Venus. New Views of the Solar System and Galaxy. Proceedings IAU Colloquium No. 196, 2004, pp. 242-53

2.  My thanks to Gary Gilligan for this.

3.  For related interpretations of ancient graphic evidence, see Why Topless?  Why the Snakes? and The Great Serpent Mound Was an Effigy of Venus.  For the underlying planetary science, see The Outer Solar System Origin of the Terrestrial Planets.