Category: Urban Astronomy

Urban Astronomy – Conjunction in December

Posted December 2, 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. 

Background: Occultations

Jupiter and Saturn were already close together in November.  Now they are bound for near-occultation in December.  An occultation is when one astronomical body passes in front of another.  It happens quite frequently with the moon passing in front of stars and sometimes planets.  Occasionally planets and asteroids do so.  Long ago, before space telescopes and sophisticated image processing, these occultations were used to characterize the shape and size of asteroids by distributing observers across the planet to time the disappearance and reappearance of stars as the asteroid passed in front of same.  To understand this, imagine the shadow cast by asteroid across the face of the Earth.  The durations observed by various locations measures the shadow precisely.  This was done in the case of near-Earth asteroid Eros and its shape was determined to be something like a fat cigar.

Much later, Eros was visited by a space probe called NEAR (Near Earth Asteroid Rendevous).  You see below that the shape was confirmed.

Near Earth Asteroid Eros: (remember, I said “something like…”)

Explanation

I told you all that because it is interesting.  But that won’t happen with Jupiter and Saturn.  Rather, they will be so close in the sky that it will take near-perfect vision to see them as two objects.  Once again, I will use the moon as a sort of cursor to point out this event.

On December 16, 2020 at 6PM (this is Central Standard Time in Houston) you will see – low in the Southwestern sky –  a thin crescent moon near the pair of planets that will appear only a fraction of a degree apart.  Please remember that your thumb at arm’s length covers about one degree of sky.

Illustrations

An image of what you will see from The December 2020 Great Conjunction  By Graham Jones, appears below. 

A sky map – from Heavens-Above.com –  like those I’ve shown before, appears below:

Epilog

Keep watching over the following week – you will not have the moon as a landmark, so, remember where Jupiter and Saturn were on the 16th and look there again. On December 21, the two will be about one tenth of a degree apart.  This close an approach of the two planets last happened on July 16, 1623.

Hasta Luego,

Steve

Artist’s conception:   https://www.timeanddate.com/astronomy/planets/great-conjunction

Heavens-Above (Houston):   https://heavens-above.com/main.aspx?lat=29.7382&lng=-95.6329&loc=13811&alt=0&tz=CST

Heavens Above (Oslo):     https://heavens-above.com/main.aspx?lat=59.9133&lng=10.739&loc=Oslo&alt=0&tz=CET

Averted Vision

Posted November 25, 2020

Urban Astronomy

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. 

Prelude

Astronomers have known – for centuries – a secret that reveals the true nature of God! Doubt me if you must, but listen to what I have to say and see if you do not agree.

These astronomers, from centuries ago until now, have all either learned by experience or have been told of an odd thing called “averted vision”. 

Explanation

This situation comes about because vision is ruled by the light detecting nerves in your eye. There are two types, “rods” (low-light sensitive and color insensitive) and “cones” (color sensitive and high resolution but 40 times less sensitive to light in general)

The center of your field-of-view is just lousy with cones and that’s how you read small fonts and so forth.   Your peripheral vision (“in the corner of your eye”) is loaded with rods that detect light quite well, but are not particularly descriptive about it.  It is described in more detail at Sky at Night Magazine

So, over the centuries astronomers learned to look away slightly in order to see more of what they wanted to see. Sounds a bit silly, does it not?

Quotes

Lyrics from Pink Floyd’s Comfortably Numb:

“…When I was a child
I caught a fleeting glimpse
Out of the corner of my eye
I turned to look but it was gone
…”

You will notice that this short quote pretty much describes what I have been talking about.  The rest of the lyrics have been interpreted by others quite differently as you will see at that link above.

Discussion

So, what of this claim about the true nature of God?  This is the first clue I had that God is the biggest (of course) Practical Joker in the Universe. 

Imagine this conversation:

God: Do you want to see that better?

Mortal: Well…yes, I do.

God:  Don’t look at it!

Mortal:   Say What?!

God: You heard me!

(a pause)

Mortal:  Hey, wow!

God:  Told ya! (chuckle)

Some will tell you that this is just “Evolution”.  Others might say that it is God’s Will.

And at least one man asked, what’s the difference?* It was Pope John Paul II – who had no problem with “Evolution”.

*About Life in general, not just averted vision

Epilog

Somehow a small planet created beings capable of asking how they came to be there. It is the only such place we know of.  This even though we have actively looked for extra-terrestrial life and/or intelligence – with steadily increasing range, accuracy and sensitivity – for about a Century.

Say, perhaps all of Life is God’s Practical Joke on the Universe!  😉

Hasta Luego,

Steve

https://www.skyatnightmagazine.com/advice/how-to-master-the-art-of-averted-vision/

https://songmeanings.com/songs/view/2832

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

Urban Astronomy – Mars in October

October 19, 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.  😉

Urban Astronomy

    I used the moon as a pointer for Saturn and Jupiter last time.  On October 29, the moon will be over by Mars in the evening sky.  I include a sky map for that date at 20:00 (8 PM) – from Heavens-Above.com” – below. 

Skymap from Heavens-Above.com  

 The moon will be near full at the time.  Mars happens to be near its closest to the Earth right now, as well.  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.

    When this reporter was young (an era also referred to as the Cretaceous Period), it was thought that Mars must certainly harbor life – at the very least, plant life – since it showed seasonal changes that were attributed to vegetation.  After a fly-by passage of the space probe Mariner 4 past Mars, it became apparent that Mars more closely resembled the crater-covered surface of our own moon.  Measurements of the atmospheric pressure on the Red Planet also made it quite unlikely that life as we know it – could survive on Mars.  Subsequent orbiters and landers have all failed to produce evidence of life on Mars.  The seasonal changes are now known to be dust patterns.  While the seasonal ice caps at the poles do contain water ice, they also are composed of carbon dioxide ice frozen out from the mostly CO2 (and extremely low-pressure) atmosphere.  Despite what many ill-informed Mars enthusiasts think, a human would need – for a walk on Mars – a space suit just like those used by Moonwalkers of the 1960’s/70’s.  Still, Mars would be “A Nice Place to Visit”

   Mars is where the moon is and about as bright as it ever gets.  Ya’ can’t miss it!

   Notice that Jupiter and Saturn are still hanging around at 8 PM – both are not far from where they were previously.  You should be able to spot them unaided,  but use the skymap, if not.

   Mars and the moon will be up all night, not just at 8 PM, so don’t try to use that as an excuse! 😉

Urban Astronomy

 

October 17, 2020 Introducing a new category

Despite this reporter’s career as a Geophysicist, he was an Astronomer by education.  These fields of study overlap when the Astronomy is “planetary”, since Geophysics involves the study of a particular planet to be found under the feet of a standing Astronomer.

  Your Humble narrator also has the habit of swimming – the only form of exercise he can manage to “stick to”.    If one can manage to show up at the pool early in the morning, a single-use swimming lane is to be obtained.  Large swimmers are particularly disadvantaged when “sharing” lanes – and said narrator is large. 

    Reporters are often instructed – by Editors – to refer to themselves in the third person (as above).  Since I am my own Editor here, I am now putting an end to that.

      If I can snag a lane in the outdoor pool, I am able to swim alone and in relative darkness, but even so there is considerable urban lighting with which to contend – not to mention the glaring lamps in the sides of the pool.  Nevertheless, the Astronomer/Swimmer takes note when there are visible stars and planets available for viewing.  

   A few months back, it happened that there were four planets visible from the outdoor swimming pool.  My natural tendency is to point things like this out perfect strangers.  However, some of the people around at this time of morning know me – by sight at least.  And we are all eccentric individuals, or we would not be swimming at 5 AM.  Since having four “Eyes Only” planets in the sky at once is a fairly rare thing, I pointed these out.  The average reaction was one of surprise.  They had no idea of what was over their heads.

The oldest Astronomer joke in the world is to promise to point out one more than the number of planets actually visible.  So, I promised five and pointed out four.  The punch line of this ancient bit of comedy relies on the audience to ask where the fifth one might be. Then the Astronomer replies,  “You’re standing on it!”.   Of course, no one asked about that fifth planet and the joke went flat.  Don’t you people have any curiosity?  Yes, it is an old joke, but none of them ever heard it before – because it is so old.

   Now, the interesting part about that stale humor – if you think about it – is the point it makes.  Specifically, that all those small round lights that this Swimmer is pointing out are actually massive worlds – a lot like the one we are standing on.  Some of them are stunningly larger, some smaller than our own planet.  Some are closer to – or farther from – the Sun.  There are places where “the world” is profoundly different from the “world” we experience.  With those thoughts, the human imagination is expanded beyond the mundane existence of day-to-day life.

  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 paragraph.  So, at this point, I know my audience.  😉

Some description of how far apart objects in the sky is needed, and “degrees” are another unfamiliar subject for Urbanites.  Extend your thumb and put it at arm’s-length and close one eye.  Now your thumb covers one degree of sky.  For Apollo 13 fans – this is why Jim Lovell was making the same weird gestures.  He was, in fact measuring the sky in degrees.

  Most Sophisticated Urbanites are also unfamiliar with compass directions.   The moon shows up pretty well, however.  So, I will use the moon to “landmark” where you Urbanites should look to find points of interest in the sky.  Those will be planets mostly, since at least four of same are bright enough to be seen in the City Glare.  The moon moves quickly across the starry sky, so pay attention to the dates and times. This first installment is for the night of October 22nd at 20:00 (8PM). 

Skymap from Heavens-Above website:  https://heavens-above.com/SkyChart2.aspx This link is calibrated from my patio. If you are near me, it will work for you. If not, you can change the location to your own house, with one of the links at left of the homepage.

At that date and time the moon will be near Jupiter and Saturn in the South-Southwestern sky.  Jupiter and Saturn are approaching a conjunction which will peak in December when the two planets will be within a tenth of one degree of each other – in the Earth’s sky, only.  They will actual be separated by about five Astronomical Units.  And – an AU is the distance from the Earth to the Sun (about 93,000,000 miles).

   All of my description, the thumb-and-one-eye-closed bit and the skychart are just illustrations.  This is Urban Astronomy – just look where the moon is!  😉