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.
If the sky is clear, you will find Jupiter Venus the Western sky just after sunset (1). If you manage that, have a look near overhead at Mars (2), the Moon (3) over to the East and for Extra Points, the (4) Constellation Orion. Please see revised chart for March 4, ’23, at 6:30 PM,below
The comet brightness fell suddenly just as the sky cleared off. I should say that this sort of behavior is to be expected of comets. As the approach closer to the Sun, gasses evaporate straight from solid to gas (“sublimation” it is called) and the expanding cloud reflects more light than the chunk of rock and ice alone. These gasses get blown away by the Solar wind, and the comet dims again. If this did not happen, the comet nucleus would simply reflect sunlight and its “light curve” would look like the green dotted trend I calculated. I added the observed brightness for Feb 4 – which happens to fall near that curve.
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.
The comet is now well-within visible range – but it will take considerable snakey-eyed concentration to pick it out. More importantly, there will be clear skies on Friday night. I put together this chart with instructions. Print it out and follow instructions. If you need light to see the chart, close one eye while you turn on the flashlight. Or, use an eye-patch to keep night vision in one eye while consulting chart. Professional Astronomers do this, while making corny pirate jokes. 😉
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.
See Mars and Jupiter in Close Conjunction, Sunday, May 29 – around 5:30 AM Central Daylight Time
Sky Chart from Heavens-Above.com May 29 at 5:30 AM CDT (UTM -5)
You can print out the chart and hold it with East at the bottom while facing East – to match up the planets with the chart. Cloudy weather is probable, so check in the days before and after, just in case.
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.
See Venus and Jupiter in Close Conjunction, Saturday, April 30 – around 6 AM
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.
Comet 2021 A1 – Leonard Dec 20, 2021
Leonard is even brighter – in fact much brighter – tonight. The current magnitude of Leonard is +2.3 (the smaller the number, the brighter – the comet was +4.6 yesterday and Saturn is +0.23 – VERY bright by comparison) so in the city, the Comet is visible and would be still better seen with binoculars.
You may have heard the expression “by an order of magnitude” – well this is over two orders of magnitude – OK?
Once again, do not use telescopes or binoculars to view the Sun – blindness will result! I said “after sunset” so you should be OK if you listen to me. 😉
As is usual in these cases, the comet gets brighter not only because it gets close to the Earth. It also gets brighter because it gets closer to the Sun. The third brightening influence is the material that the closer sun vaporizes. That stuff makes a cloud around the comet and is it also partially blown away by what is called the Solar Wind – in a comet’s tail.
Figure 1, above shows the location to view, which is conveniently close to Venus, which is the brightest thing in the sky. If you can see the Planet, you should be able to see the comet – although you may need those binoculars to do so.
The sky is currently “mostly clear” (look-out-window method) in Houston at 3:22 PM. Sunset is at 5:26 PM. These next few days are literally the last chance to see Leonard, as it is on a hyperbolic orbit – which is a nerdy way to say that it will never return to the Solar System. (Please see figure 2 below)
For readers not in the Houston area, just look for Venus (and Jupiter for orientation) and use the chart in Figure one above to find the comet. We are lucky to be able to have the two brightest objects in the sky (now that the moon is not around in the early evening) as our reference points.
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.
Comet 2021 A1 – Leonard
There is another “Eyes Only Visible” comet to be seen in the Southwestern sky, just after sunset. The current magnitude of Leonard is +4.6, so in the city, it is only just visible and would be better seen with binoculars. Once again, do not use telescopes or binoculars to view the Sun – blindness will result! I said “after sunset” so you should be OK if you listen to me. 😉
As is usual in these cases, the comet gets brighter not only because it gets close to the Earth. It also gets brighter because it gets closer to the Sun. The third brightening influence is the material that the closer sun vaporizes. That stuff makes a cloud around the comet and is it also partially blown away by what is called the Solar Wind – in a comet’s tail.
Figure 1, above shows the location to view, which is conveniently close to Venus, which is the brightest thing in the sky. If you can see the Planet, you should be able to see the comet – although you may need those binoculars to do so.
We have had very cloudy weather here in Houston (today, Dec 19) is “Mostly Cloudy” at 4 PM, changing to “Cloudy” around Sunset at 5:26 PM. Tommorow at Sundown the prediction is “Mostly Cloudy” and the comet will have moved slightly relative to Venus. These next few days are literally the last chance to see Leonard, as it is on a hyperbolic orbit – which is a nerdy way to say that it will never return to the Solar System. (Please see figure 2 below)
Figure 2. Comet Leonard is diving through the Solar System, never to return.
For readers not in the Houston area, just look for Venus (and Jupiter for orientation) and use the chart above to find the comet. We are lucky to be able to have the two brightest objects in the sky (now that the moon is not around in the early evening) as our reference points.
Once again, we – on Earth – will be passed by a Near-Earth Asteroid. This time on April 12th. Don’t worry! Its nearest approach will be about 38 thousand kilometers (23,800 miles). For reference, the diameter of the Earth is about 8000 miles. The size of this is a rock that you could hide a Ford Expedition behind.
Near Earth Asteroid…Date……….Miss Distance…..Velocity (km/s)…..Diameter (meters)……
Figure 1: Parameters of Near-Earth encounter with 2021GW4
Figure 2: Orbits of Earth, the Moon and 2021GW4. These are calculated without the Earth’s gravity effect on the asteroid’s orbit. The red line suggests what might happen in reality.
The question on everyone’s lips is always what will happen IF this asteroid were to collide with the Earth. It will not do that, OK?
People just love to imagine catastrophe and asteroids are their greatest opportunity. So, I have developed a macro to calculate such a disaster given the mass of the asteroid and the relative velocity of that asteroid with the Earth. Now, there are many variables (also referred to as “parameters”) that effect such calculations and I have made many assumptions – based on “average” values of density – and so forth. So, if you calculate a different number, please let me know – and show your work!
With all those disclaimers, I will say that the asteroid’s impact – if its course were to coincide with the position of the Earth (which WILL NOT HAPPEN, by the way!) – would generate an explosion equivalent to 1.3 kilotons of TNT. This is calculated by the Kinetic Energy using the estimated mass of the NEA and the velocity from the table in figure 1.
For reference, the bombing of Hiroshima yielded an explosion estimated at 12 to 18 kilotons. For an extreme example the “Tsar Bomba” detonated by the Soviet Union in 1961 yielded about 50 Megatons (50,000 Kilotons). So, we have already done far more damage on our own than this particular object could heap upon us.
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?
“…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! 😉
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.
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 theHeavens-Above.commap 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.
GoingWalkabout.Blog 