Telescope Reviews: What if Venus had a moon?

This is not a question, and there is no graphics art in it, but it's more the result of the musings I have while I drive to the office in the morning:question:, or look through a telescope. :o

I hope some will find it dream provoking, if not thought provoking, and perhaps will give some ideas to you astro-artists.

Often it is wondered what life would be on earth without the moon. Or farther away from the sun. Or from another viewpoint in the Milky Way.

Has anyone wondered why Earth alone in the Inner Solar System has a large satellite? Mars has Phobos and Deimos but hey are "just" asteroids.
One could wonder, when for millenia Astronomers and theologians alike have wondered at the perfect roundness of the Moon, and devised from it conceptions of the world with the "upper" world being perfect and the "lower" world (Earth) bein imperfect. If Earth had been orbited by a low flying potato shaped body, things would have been quite different.

If Venus had a moon, we should suppose the system would look a lot like the Earth - Moon system : so close to the sun, it would be unlikely to have a moon forming far from the planet like in the outer solar system. (The Lagrange point where Earth's and the Sun's gravity balance each other is 1000000 km away from Earth ; for Venus it is 400000 km). We should expect it to be a little closer to the home planet - let's say 200000 km.
That would mean that at greatest elongation, Cupid would be 16 arc-minutes from Venus, or half the Moon's diameter as seen from Earth; probably good enough to see with the naked eye. The pair would be a blazing sight: a little like a close conjunction of Mercury and Venus.

In a small telescope, things would get quite exciting. The pair would be seen as a pair of cescents and the danse would certainly be an endless pleasure for celestial mechanists and casual observers alike. When Cupid would be between Venus and the Sun (being in the crescent phases as seen from Venus), Venusshine might be seen on Cupid's night side. It would be a test of an Earthbound observer to notice Venusshine on Cupid, lost in Earth's twilight and in the glare of Venus.

Mutual events of Cupid and Venus would also offer a spectacular signt. With Venus's axis being straighter than Earth's and Cupid closer to its home planet, they would be more frequent. Eclipses of Cupid would combine the effect of Lunar eclipses from Earth with the sideway view: we would see a crescent being obscured and not a disk. The colors on Cupido would provide an insight on Venus's athmosphere. And when Cupid creates an eclipse of the Sun on Venus, an Earth observer would see an elongated shadow creeping on the side of a crescent. Before telescope times, observers might have seen a diminishing of Venus's brightness, like when witnessing Galilean Satellites mutual events with a backyard telescope.

What observing Cupid with a large backyard telescope would reveal is a trick question. Would its surface markings be with low contrast, like on mercury, making them impossible to view from an earth-based telescope? Or would surface features like the lunar maria be visible as subtle markings, like Mars seen from Earth? In this case Cupido would be the only satellite with the moon to reaveal surface markings from Earth. In all likelyhood, Cupid would like the Moon always show the same face to Venus, but Earthlings would be able to see its hidden face. Would Cupid be a dead world like the Moon? Being small like the moon, but close to the Sun, Cupid would be scorching hot but dead (just like Mercury). If Cupid had been closer to Venus, maybe it would endure the same kind of tidal heating as Io. Maybe it could have had volcanoes. They would probably not be visible from earth, but perhaps their plumes would tell them away.

Scientific implications of such a state probably would have saved Giordano Bruno's life. Humans would more likely have admitted earlier that their planet was one in many, and thus not the centre of the world, in a Solar system with an Earthly twin. Eclipses of the sun and moon would have been understood earlier. Calendars would have been more sophisticated. If the orbital period of Cupid's orbit was in some kind of "resonance" with the Earth Year, it would allow for better calendars than those based on phases of the Moon. Copernicus and Galileo would have needed to find another scientific revolution to start. Galileo would not be remembered more than Asaph Hall (quizz: who is Hall? He discovered Phobos and Deimos, the satellites of Mars). Nasa would be less excited about the outer Solar System's satellites, with one to study firsthand, and one that could serve as a springboard to such a strange planet as Venus.

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Matt
CI700 mount with various scopes on top.