Established Member
Venus spins at its equator at a mere 5mph, compared to the Earth's 1000mph.
If one could see through its clouds, what would see from Venus' surface i.e. how would the Earth, Moon, Sun, Mercury Mars and stars appear to move during a Venusian "day"?
And during a Venusian "year"?
Order of Kilopi
There is a partial answer here: http://www.universetoday.com/47898/l...-day-on-venus/
Order of Kilopi
Do you have any reason for anything more complex than the obvious answer of "they would move slower and backwards"?Originally Posted by wd40
I can't think of any other way they would be different except (of course) thier positions.
Established Member
Various applications will provide a view of the sky as if you were standing on a given planet's surface, such as Venus. One of those apps is Luminous, for either iPhone or iPad.
Established Member
How would the thought process of a thinking Venusian have evolved with such a day?
On Earth, the sun crosses the sky in c12hours ie 15 degrees per hour. This sight helped formed the Geocentric view of mankind and its history which held sway for 250,000 years, everyone convinced that they were 'special' at the center of the universe at the focus of a Creator's attention, until the 'actual' state of affairs was demonstrated only quite recently.
On Jupiter, with its 10 hour day, a Jovian would see the sun cross the sky at a whopping 36 degrees per hour; presumably he'd feel even more 'special'.
But at an imperceptible fraction of a degree per hour, presumably an early Venusian would have evolved a totally different philosophical outlook on the universe i.e. his Cytherocentrism would be weaker than a Jovocentric's?
Last edited by wd40; 2012-Jun-12 at 07:38 AM.
Order of Kilopi
I really have no idea why you think the speed of rotation would have any effect at all. Wouldn't a more important issue be the cloud cover, for example? Depending on the thickness of the atmosphere your view outside would be quite clear or not so clear.
I'm intrigued. How do you know how people felt 250,000 years ago? From writings or audio recordings? How do you know the view was geocentric and not village-centric?
As above, so below
Moderator
Not only that, geocentrism surfaced after the heliocentric model, which was proposed e.g. by Aristarchos of Samos a few centuries before CA, and I think the Pythagoreans were also in favour of this model.
Only when the christian church became more and more important the geocentric model became "dogma".
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Order of Kilopi
I doubt it. We have been charting the movement of planets among the stars for thousands of years. We have been charting the movement of constellations for thousands of years.
With that in mind, people would have soon seen that the sky changes throughout the year and noticed that they go "across" the sky in the same way.
Established Member
At the risk of thread wander - can you point me to a more detailed history on this? The "standard" view for astronomical history has Aristarchus' ideas being argued down, most cogently for lack of observed annual parallax or distortion of constellations, and a deliberate choice for a geocentric view (or at least geocentric calculations, since for a long time astronomy was though to be capable of nothing beyond saving the appearances"). Ptolemy wrote the Almagest over a century before Constantine's conversion gave Christianity acceptability in Roman territory, and it seems devoid of any hint of heliocentrism despite its otherwise overarching reputation.
Order of Kilopi
I would not expect Aristarchos to have come up with a heliocentric model without some sort of orbital or heavenly spheres model already in place in the collective lines of thought, as opposed to a merely 2-dimensional plot of the planets' looping motions across the sky. During the first baby steps into developing real scientific theory, I would expect a geocentric model to be an obvious common-sense default position. To our everyday senses, the Earth is a large stationary platform while the heavenly bodies appear to be small objects passing overhead perhaps no higher than the tops of the clouds.
In principle, observers could work over many centuries from a local village-centric or farm-centric line of thought and empirically derive a good ephemeris for the planets by watching their looping cycles of motion across the sky and keeping good records. They could assume a flat Earth and not even be bothered with where each object is or what it is doing while it is out of sight. That would be similar to deriving tide tables for a particular port, which was done before anyone knew what was causing the tides physically.
Administrator
As speculation on the thought processes of hypothetical Venusians with a hypothetical clear sky do not seem to have "straightforward, generally accepted answers", I moved this thread from Q&A to Astronomy.
Moderator
Maybe my memory is a bit off, I would have to look it up.
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