Urban Astronomy -Venus in November

Posted November 1, 2020

The night sky is pretty much a mystery to most City Dwellers.  The glare of city light drowns out all but the brightest stars – and planets don’t do much better.  If you are interested, I can tell you where to look to see these far-off worlds.  If you were not interested, you would have stopped reading after the first sentence.  So, at this point, I know my audience.  😉

 Our story so far:  Your Humble Reporter has shown you Saturn and Jupiter and Mars in October – in both cases using  the moon as a pointer. This time the crescent moon will be the landmark for Venus – and possibly Mercury.   I include a sky map for November 12 at 6:00 (6 AM) – from Heavens-Above.com – below. 

Skymap from Heavens-Above.com  

   The moon is always near “crescent” phase when it is over by those planets, because they are always near the Sun.  I will pause now while y’all think about that! 😉 

 The sky map can be used by printing it out and holding it (or your phone, with the chart displayed) over your head.  You need to orient the chart with the sky, of course.  If you know where the North Star is, use that – or there are more than one compass apps for your phone to be downloaded for free.

    In the early-to-mid part of the Twentieth Century, it was thought that Venus might be a steamy jungle-covered planet – beneath the all-concealing clouds that made such speculations plausible. An alternate speculation was that Venus was covered with a vast ocean of soda water – created by absorption of the thick carbon dioxide atmosphere.  Carbons dioxide does not rule out life – quite the reverse!  Plants love the stuff!  Also, the exact composition of the atmosphere was not known until relatively recently (if you are as old as I am) 😉

All that interesting imagination did not come close to the real story, which is a crushing, thick atmosphere, dry as a bone and hot enough to melt Lead on the surface.

Still, Venus would be “A Nice Place to Visit”.  Well, not really nice…more like interesting – and deadly.

There is a more welcoming place on Venus, however.  This is an exert from my article “Habitability”  (as yet unpublished):

“So, if by “habitable” we mean: A natural environment where we could walk around “in shirt-sleeves” (as they say) while breathing the unaltered atmosphere: No, there is no such place beyond Earth.

Well, perhaps if we allow that we might have to bring our own air, but keep the “shirt-sleeve” aspect?  There are some interesting possibilities.  What’s needed is something like the atmospheric pressure that we tolerate here and that can actually be found at Venus.  Not on any surface, you understand, but high in the atmosphere.  [2]

At about 50 kilometers (30 miles) above the surface of Venus, the atmospheric pressure is about half that of Earth at sea level.  The temperature is roughly 27 °C (81° F).  This should be survivable while breathing air that you’ve brought with you.  The temperature changes with altitude as the pressure does and some combination of the two might be found where outdoor activity might be possible.  Details of what sort of oxygen/nitrogen (helium?) mixture to breathe at what pressures will have to be determined.  High-altitude aerospace engineers and deep-sea divers could probably work this out in no time. 

The alert reader will notice that this CO2 rich environment – with its Earthlike pressure and temperature (and sunlight) could well support unprotected plant life. There is no reason that a crop of fast- growing plants could not supply food, as well as the oxygen required for breathing and buoyancy. 

*Note that this “outdoor” activity will be limited to walking around on exposed decks in some sort of zeppelin – we had such vehicles in the early years of the previous century.  No great leap of technology there.  This hypothetical airship – suspended by balloons filled with any combination of oxygen or nitrogen – would float in the heavier CO2.  There is, however a haze of sulfuric acid in the carbon dioxide of the Venusian atmosphere that must be considered.”

Habitability – Steve Campbell

  Back to the viewing on Nov 12:  The elusive Planet Mercury may also be visible – about half-way between the Moon and the horizon.  Not for me, mind you, since I have the enormous, glaring Houston Metroplex to the East of me – but maybe for you.  Once again, you can change the viewing location on the Heavens-Above.com map to depict your own sky.

   Mercury, back in the “old days” was thought to be “tidally locked” (always with the same side to the Sun).  Mercury is in an elliptical orbit and it turns out that it is weirdly revolving in a 2/3 resonance that is also a stable response to tides.  They thought Venus was “tidally locked”, as well.  The truth about Venus is that its day is longer than its year.  So weird is this story that I don’t have time to explain it. This is another illustration of how Scientists are always right, except when they are wrong.  When somebody wants to talk to you about “Settled Science” read them this article! 😉

   Mercury’s rotation axis is almost perfectly oriented at 90 degrees to its orbit, which means that the craters at its poles are permanently shadowed from the Sun. Observations of those polar regions of Mercury have produced evidence of water ice in those always-dark craters.  So, the closest planet to the Sun has been proven to have water ice, as does the third planet (that’s us!).  Yet, the second planet is the hottest and driest (i.e., no water- solid or liquid but perhaps some gas). Again, nobody thought so until it was made obvious to them.

   Before we sent space probes to those planets in the 60’s and 70’s (as witnessed by your Science Nerd Humble – and Ancient – Reporter), we didn’t know this stuff and what we thought we knew turned out to be wrong.

Ex Scientia, Trivia!

Steve

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