As a lifelong Astronomy Nerd (perhaps not at birth, but not long after) I cannot help but notice how Planetary Science has advanced over the last half century. To say that much has been discovered is a ridiculous understatement. This theme of Solar System Astronomy can also be noticed in my other Categories (Comets, Planets, Asteroids, Urban Astronomy, Science and occasionally even in Going Walkabout, Energy, One Climate Fact and Humor*.
*These are the collections behind those icons on my homepage atGoingwalkabout.blog.
As related below the body now officially named 486958 Arrokoth was indeed described and analyzed at the 50th Lunar and Planetary Science Conference in 2019.
Prolog – March 2019
As expected, the LPSC has revealed much greater detail about the Kuiper Belt Object 2014 MU69 (A.K.A. Ultima Thule)
The flyby of this Kuiper Belt Object was declared a 100% success by the Principal Investigator Alan Stern. The closest approach was at about one fourth the distance as the previous KBO encounter with Pluto. This is not surprising when the new target is comparable to a small mountain on Pluto. That, and the fact that the velocity of the probe is about seven miles per second (yes, per second) complicates the task. Other compounding circumstances were the light level comparable to a moonlit night on Earth, a spacecraft design that does not allow continuous contact and a download rate that is agonizingly slow. As discussed earlier these were design trade-offs that made a long, difficult exploration effort possible – and quite successful – on a limited budget.
At the time of the Special Session at the LPSC, it had been 80 days since the encounter and considerable data had been received. However, more than a year separates us from the completion of that transmission. The state of knowledge at this time was summed up by the PI in the first presentation and those items are presented below along with details filled in by the presenters that followed.
Post-flyby Observations
An earlier comparison to a “snowman” shape were based only on a 2D view. Both the bodies that makeup this contact binary are thinner in the third dimension. The larger one (now popularly called “Ultima”) is actually shaped more like a thick hamburger patty. The smaller body (Thule) is more nearly spherical, but still visibly “flattened”. This is not unprecedented. There is a moon orbiting Saturn called Hyperion that has a similar shape to Ultima’s.
As promised, the resolution now available is greatly improved. The panel below is a stereo “cross-eyed” view. It takes a bit of practice, but it is possible to focus the left eye on the right image and vice-versa to get a clear and vivid 3-D view that appears between the two. Sit up straight and view with no tilt on the image. Hold your head very still and adjust by tilting slightly right or left. It should resolve into a clear and quite impressive 3-D image. I find it works best, with minimal eye-strain at about 2 feet (about 60 cm) away.
Figure 1: Raw images of the contact binary MU69. These are from the LORRI instrument and therefore lack the red coloring or the previous, low resolution image. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
Other observations:
The crater on the smaller body (Thule) is seen to be quite deep. It may be an impact feature, but no one has dared to unambiguously claim so. Other craters may have been caused by faulting, perhaps during the merger. None of the few craters seen can definitely said to be caused by impact.
A comparison was made to Phobos, the greater moon of Mars, and its biggest crater named Stickney. The two bodies are roughly the same size. Phobos is one of the darkest objects in the inner solar system and in that sense, also very similar to Thule. See Figure 2 for a side-by-side images.
Figure 2: Left: MU69-B (Thule) and Crater “Missouri” Right: Martian Moon Phobos and Stickney Crater
Credit: NASA
Sidebar
Phobos and the lesser moon of Mars, Deimos were discovered by American astronomer Asaph Hall in 1877. Hall was about to abandon his search for Martian moons, but was convinced to struggle on by his wife, Professor Chloe Angeline Stickney Hall.
Somewhere in the vast body of writings by Issac Azimov (and almost certainly somewhere in the shelves and piles of ancient paperbacks I still possess – and have forbidden my wife from recycling) is told the anecdote about a presentation wherein the speaker related this story and hoped – that when Phobos was ultimately imaged – a major feature might be named for the mathematician, suffragist and abolitionist who would not let Hall give up the search in which he ultimately succeeded. When the presenter (who may well have been Azimov, himself) admitted his ignorance of her name, an attendee stood up and shouted, “Angeline Stickney” (for she did not use her first name). And, in the fullness of time, it came to pass that the crater that dominates the surface of Phobos is so named.
More Points about 2014MU69 / Ultima Thule
Bright spots tend to be in low zones. Troughs and mounds are clearly discernable.
The merger of these two bodies into one was determined to be a “gentle one”. In the distant realm of the Kuiper Belt, and especially among the “Cold Classical”, objects that find themselves near each other tend to be moving with the same velocities. Willian McKinnon described this method of simulating the velocity of merger: “Walk into a wall”.
No satellites were detected. Nor was there any detectable atmosphere.
This may be because any satellites there might have been would have been ejected from orbit during the “merger” process.
It is my (your humble narrator) own interpretation (2021) that this system once consisted of five or six main bodies – all orbiting in the same plane – that were slowly accumulated onto the larger of the two. And then the accumulated “hamburger patty” (whose shape indicates the co-planar rotation IMHO) and the smaller body finally merged. Tidal stresses in orbiting bodies tend to slow down the mutual rotation – thus bringing them all together.
The period of rotation has been pinned down to 15.9 hours.
What’s Next?
The New Horizons spacecraft probably has enough fuel to re-direct to another Kuiper Belt Object. There is not yet a target body known to be in reach and Ultima Thule was found at the limits of the Space Telescope capability. It is expected that the probe’s own long-range imager (LORRI) will be the instrument to find the next destination. It is estimated that one more target will be the last possible. There is no hurry, however, since the probe will be in the Kuiper Belt until 2027 or so.
As a lifelong Astronomy Nerd (perhaps not at birth, but not long after) I cannot help but notice how Planetary Science has advanced over the last half century. To say that much has been discovered is a ridiculous understatement. This theme of Solar System Astronomy can also be noticed in my other Categories (Comets, Planets, Asteroids, Urban Astronomy, Science and occasionally even in Going Walkabout, Energy, One Climate Fact and Humor*.
*These are the collections behind those icons on my homepage atGoingwalkabout.blog.
This is a summary of what I knew about this fly-by of 2014 MU69, going into the Lunar and Planetary Conference (LPSC) of 2019. I subsequently wrote a “post conference” summary and many editions and deletions later, the foreshortened, simplified result appeared in Ad Astra Magazine: STILL SEEKING NEW HORIZONS: Ad Astra – Summer 2019 page 48.
A great deal of the detail that I included in this preliminary draft was left out of the final product. The length, format and tone were, of course, the choice of the editor. Since this early pre-conference composition contains but little of the final result, I take the liberty of presenting it in my own publication (again Goingwalkabout.blog.)
I will also be adding original commentary and explanation, so I reckon that it is original material by any definition. My intention is to also present (later) the post-conference story – partly in original form – which contained quite a bit of detailed and interesting information that did not fit Ad Astra’s “tone and format”. Not to criticize Ad Astra, you understand, but only to display my own interest and enthusiasm for richer detail. And, I want to present some of that in my own publication, free to read (and – alas – to write for) though it may be.
Before the Lunar and Planetary Science Conference in 2019
New Horizon Fly-by of Kuiper Belt Object (486958) 2014 MU69 (a.k.a., Ultima Thule)
By Steve Campbell
February 2019
After a successful fly-by of Pluto in July 2015 (to read more, please see Sneaking Up on Pluto, Part Iand Part 2), the New Horizons space probe followed up with another encounter on New Year’s Day 2019. This target was a much smaller body known as 2014 MU69 and frequently referred to by its nickname “Ultima Thule” (and subsequently “officially” called 486958 Arrokoth – as of late 2019)
The first opportunity for publication and presentation of those results will be the Lunar and Planetary Science Conference and will take place between March 12th and March 18th, 2019. The limited data transmission capability from New Horizons had the result that less than 1% of encounter data had been received when the LPSC abstracts for presentations were due. As one abstract’s introduction states,
“Therefore, many new, quite substantial results not available at the time of this abstract submission will be presented in the actual review talk.” (4)
Pluto and MU69 are both Kuiper Belt Objects. I will now explain what that means.
The Kuiper Belt
As of the 1930’s, the Solar system had been thought of as divided into the realm of the planets and the distant Oort Cloud. Dutch astronomer Jan Oort deduced this spherical “halo” of objects by studying the movements and behavior of long-period comets. A third zone between those two was later postulated to explain the many “short-period” comets that tend to be near the planetary plane and have periods of 200 years or less. Since the discovery of Pluto it had been suspected that a torus of such small bodies existed. It was named for Gerard Kuiper (1905 – 1973) who was a Dutch-born American astronomer and planetary scientist of great distinction. In an appropriate coincidence, Jan Oort was one of Kuiper’s teachers in Holland in the early years of the 20th Century.
Subsequent discoveries of Kuiper Belt objects (now in the thousands) have led to a more detailed division of zones within and near the belt. KBOs are distinct from comets only because they are so far from the sun that they do not produce the comas or tails.
Centaurs: These are KBOs orbiting in the zone of the outer planets, thought to have been scattered there from the Kuiper Belt by the gravitational influence of (primarily) Neptune. From there they may be further thrown sunward by the other giant planets.
Resonant: This applies to a KBO whose orbit crosses that of Neptune. These will not be thrown sunward further since their orbital periods are such that they always find themselves far from Neptune. Pluto is the prototype Resonant KBO and has an orbit that takes it around the sun twice for every three orbits of Neptune.
Cold Classical KBOs: These are KBOs that stay in the zone outside Neptune’s influence and thus avoid being re-directed by that planet. The “Cold” qualifier refers to the fact that these orbits are not inclined to the orbits of the planets and are near-circular.
Hot Classical: Similar to the “Cold” bunch, but these KBO’s have elongated orbits that tend to be substantially inclined.
Scattered: As you might expect from the name, none of the restrictions applied to the other categories apply to this bunch. These are the population that wind up as Centaurs or short-period comets.
New Horizons Probe
The idea of a Pluto exploration was not as a “flagship” mission like the Voyagers (Grand Tour) or the Cassini Saturn orbiter. Its goal was to target a fly-by of Pluto directly, but also to carry on into the Kuiper Belt and visit other, as yet undiscovered bodies. The budget was a shoestring compared to many previous missions and while the instruments were advanced and powerful, many compromises were made to balance the launch and timing of the mission, the way data were collected and transmitted and the cost and reliability of hardware. The vast distance to Pluto was compounded by the fact that the multiple gravity-assists enjoyed by the Voyager probes, were not possible. Only Jupiter was reasonably positioned for the “slingshot effect” — and that only for a limited time.
The result was a small spacecraft, launched away from Earth by the most powerful rocket available, adorned with extra strap-on boosters and outfitted with a third stage to achieve a record-fast trajectory.
The probe pointed its instruments by rotating the whole spacecraft – meaning that all data collection was done while the antenna that would transmit to Earth was pointed off at deep space. The images and data for the entire fly-by of Pluto and later 2014 MU69 had to be recorded and “played back” later when instrument-pointing was no longer in operation and contact with Earth could be restored. Payload considerations limited the size of the high-gain antenna, and hence, the data transmission rate. As with Pluto before, the entirety of the MU69 fly-by data will not be on Earth until well over a year after the fly-by (August/September of 2020). Besides the slow data rate, there was an additional delay because the probe had slipped behind the Sun, as viewed from Earth, in January.
Figure 1: The New Horizons Probe. Credit: NASA
The instruments are described here as quoted from the New Horizons web site (1):
“The New Horizons team selected instruments that not only would directly measure NASA’s items of interest, but also provide backup to other instruments on the spacecraft should one fail during the mission. The science payload includes seven instruments:
Ralph: Visible and infrared imager/spectrometer; provides color, composition and thermal maps.
Alice: Ultraviolet imaging spectrometer; analyzes composition and structure of Pluto’s atmosphere and looks for atmospheres around Charon and Kuiper Belt Objects (KBOs).
LORRI: (Long Range Reconnaissance Imager) telescopic camera; obtains encounter data at long distances, maps Pluto’s farside and provides high resolution geologic data. SWAP: (Solar Wind Around Pluto) Solar wind and plasma spectrometer; measures atmospheric “escape rate” and observes Pluto’s interaction with solar wind.
PEPSSI: (Pluto Energetic Particle Spectrometer Science Investigation) Energetic particle spectrometer; measures the composition and density of plasma (ions) escaping from Pluto’s atmosphere.
SDC: (Student Dust Counter) Built and operated by students; measures the space dust peppering New Horizons during its voyage across the solar system.”
The alert reader will note that the same antenna (REX) that returns data to the Earth is also listed as an instrument. It was used to measure the changes in an Earth-NH transmission as the signal was eclipsed by Pluto’s atmosphere and surface and the same situation was also measured at Charon.
The data capacity of the probe is only 8 Gigabytes. While that is not impressive in today’s realm of technology, it must be remembered that New Horizons was launched in 2006. And, as is typical in spacecraft design, the technology designated for use in the probe was “frozen” some years before that.
To put that in perspective, available memory for the Voyager probes (Launched in 1977) was actually on a ½ inch, 8 track magnetic tape with a total capacity of about ½ Megabyte and a top baud rate of 56kilobits per second (2). Since the technology was frozen five years before launch, it was some, 17 years out-of-date by the time Voyager 2 flew past Neptune in 1989.
2014 MU69 (AKA Ultima Thule)
The New Horizons space probe was a resounding success as it flew by Pluto. The long-patient team of planetary scientists were then eager to find new targets. After all, the probe was still in good shape, with enough fuel to change its direction somewhat and find more distant targets in the Kuiper Belt. There was, however, no known object in a suitable position to arrange that.
Extensive observations by ground-based telescopes found more KBOs but none within reach of the probe. So, a Hubble Space Telescope survey was commissioned by the New Horizons team and found three valid candidates – of which 2014 MU69 was targeted. (5)
Before the encounter this KBO was examined by telescope observations and distant examination by the spacecraft itself, whose battery of instruments includes a telescope (LORRI), which while not nearly as powerful as the major observatories on Earth, it had the advantage of being very much closer.
There was also a campaign of occultation observations to characterize the shape of the body and assist in targeting by precisely measuring the orbit. This is a time-tested method to characterize the shape and refine measurement of an asteroid by precisely timing the disappearance of a star that is expected to pass behind the target. The “shadow” of such a small body – itself, so very far away – is about the same size as the KBO to be measured. It is nonetheless miniscule and fleeting on the face of the Earth and is best measured by teams of observers, spaced appropriately – in this case about 4 kilometers (2.5 miles apart). They must travel to the expected path of said shadow, bring their own portable equipment and deal with weather, geography and bureaucracy. Four such occultations were observed with varying success and were, taken together, sufficient to pin down the rate of movement of MU69 and to indicate that the KBO was either a pair of close-orbiting bodies or an elongated shape, possibly a “contact binary”. For results, please see figure 2, below.
Figure 2: Results of occultation observations indicated a close binary, elongated shape or a contact binary nature of the KBO. The latter proved to be true. Credit NASA
So, rather ironically, to pin down the parameters needed to make the fly-by a success required the efforts of observers – all the way back on the Earth – mostly armed with 16-inch telescopes and other equipment that (the author estimates) could be purchased for the price of a late-model used car.
Characterization
The orbit of MU69 around the Sun is so nearly circular that the difference is less than 5 percent. This would seem to indicate that this is a primordial object, formed where it is found now and not a displaced asteroid that might have been ejected from the inner solar system, for example.
Because it is a Classical KBO, the two bodies making up the object are thought to be formed where they currently are and gently captured into a binary system where they eventually merged to form a “contact binary”. Even at this early stage the KBO is being referred to as “pristine”.
In other words, this is not something that was formed elsewhere and then cast out by gravitational interactions the outer planets. Nor was it altered much since its formation.
The spectral analysis revealed that the composition is similar to Pluto. That “dwarf planet” has been altered a great deal by differentiation as a planetary body, by an acquired atmosphere and by interaction with it large satellite, Charon.
Distant, low resolution images sent to Earth by the probe — just before the encounter – pictured the target planetoid as a close binary. The initial images (at better, but still lower resolution) pictured MU69 as a “contact binary”. That is, two planetoids so close in orbit around a common center that they are in physical contact. Please see Figure 3.
Figure 3: MU69 Credit: Nasa
The KBO is much darker than all the images herein indicate. Those pictures are “stretched” to show the difference in brightness. The true colors range from dark red to really dark red. The red color is contributed by nitrogen-rich organic compounds called tholins, which are described by the following quote from NASA
“…in the late 1970s, scientists made an organic substance in the laboratory that matched the reddest asteroids. The substance’s color spectrum ranged from yellow to red to black, and was termed “tholin” by Carl Sagan in 1980. Scientists measured and modeled the optical properties of tholins, and found that the tholins matched the observed red color of the majority of the most distant asteroids.”
The New Horizons probe has been determined to be approaching from almost a “pole-on” direction. This will limit the imaging of the other side which is mostly unilluminated at this point in the KBO’s orbit around the sun.
A great deal more data, images and analyses were presented at the Lunar and Planetary Science Conference in Houston on March 18 – 22, 2019.
It happened yesterday and you missed it completely! An asteroid passed way inside the moon’s orbit – about 5 Earth diameters away. Called 2021 AH, it was discovered only this (new) year! These things can sneak up on us all unbeknownst, sometimes.
It is bigger than the building you park your car in, and probably made of solid rock. It is traveling at a speed that would make its impact the equivalent of an atomic bomb.
Don’t worry, though. It missed by 41,641 miles – a bit more than five Earth diameters.
And if I tell you that this happens like every six months or so, I am sure you will be comforted and re-assured. 😉
I read regularly at AmericanThinker.com (AT) and they have published a few of my articles and blog posts. (that last one is not mine, but from some other author with a similar name) In a recent AT article What I Learned from the Christmas Star by Mark Deutschle that author wrote:
“…we were looking at Jupiter and Saturn, which are over 700 million miles from Earth.” That is an oversimplification that implies that those planets are actually near to each other. They are not. They only happen to be in the same part of our sky.
Also, in a conversation with my Number-One Son about science fiction, and actual astronomy, he asked me how the batteries were charged on the probe that landed on Titan (the large moon of Saturn). The answer (They were not charged, they died after a few hours.) surprised him. Why not solar panels? Because Saturn is (on average) about ten times as far from the sun as Earth. (You might have read this in my article called A Nice Place to Visit, But…)*. That means that the sunlight received at Saturn is only one percent as intense as we get here on Earth. Add the cloudy atmosphere of Titan and less than 1/10th of one percent (1/1000th) makes it to the surface of Titan.
You might think that the son of an Astronomy Nerd would know all this. It might surprise you to learn that my son does not listen in fascination to my every word. If you, indeed are surprised, I have a premonition that you are, as yet, childless – or at least “teenagerless”.
*I have written another article, along those lines – meant for actual profitable publication. If you are an editor and have any interest, let me know through the “contact” tab in this website and I can send a link and a password for you to read same.
I wrote all that so I could tell about the Scale of the Solar System. Since distances of other planets vary due to their orbits and the Earth’s orbit, the way to keep this clear in your mind is summed up with one distance – 93 million miles (close enough) which is called one astronomical unit (AU).
Then remember these numbers: 0.4, 0.7, 1, 1.5, 5, 10, 20, 30 and 40 – which are the distances from the Sun to each of the planets in Astronomical Units.
If you want to know the distance in miles, multiply each of the nine numbers by 93 million.
So:
The Earth is right now on the opposite side of the Sun from both Jupiter and Saturn. The distance from Earth to Jupiter is 6 AU’s and to Saturn is 11 AUs. The distances in miles are 465 Million and 1023 Million. The average of those two is 744 Million. So, Mr. Deutschle rounded that average down to 700 million and said “Both were farther”. In fact, Saturn is over twice as far as Jupiter and the maximum distance involved with those three planets is over a billion miles
Below is a Solar System diagram (from JPL Small body dataset browser) of the sun and planets that helps to visualize the Christmas day configuration of these three planets. In this oblique view, you can see the actual situation
Deutschle’s point in his article was that the Universe is large and majestic. So, to appreciate the Solar System even more, we can say (since Neptune is 30 AUs from the sun) that it is 60 AUs in diameter – or Five and a Half Billion Miles. You might think that the popularity of the word “billion” started recently – with the National Debt. Not so, neighbors! Astronomy Nerds were in “billions” territory more than a century ago! In fact, we knew the distances to some stars were in light years early on and the very nearest is Proxima Centauri at 4.24 light years or 1.31 Parsecs or 268,400 AU’s or 25 Trillion miles. We got to Trillions long before any of those corrupt, big-spending politicians!
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.
By the way on the date of this post, you should go out shortly before sunset and look for the Jupiter/Saturn Conjunction in the Southwest sky. Don’t look at the Sun, OK?
By the way, on the date of this post, go out shortly before sunset and look for theJupiter/Saturn Conjunction.
So far, I have used the moon as a cursor to point out the planets Venus, Mars, Jupiter and Saturn. This is four of the five “eyes only” planets and since Mercury is so elusive, we have pretty much run out of subjects. There is other stuff in the sky, of course and we might just as well look at those.
As stated in my prolog for this series, the night sky is a mystery to city dwellers and they might find stars interesting. Why – you may ask – would I be interested in points of white light that never change? Long ago, people were interested in stars because they clearly documented the progress of the seasons. If you are a subsistence farmer (and most people were) you had a vested interest in knowing when to plant and when to harvest your crops.
As these farmers – and later astronomers – studied the stars, they came to know that they are not all the same color and they actually do change – at least some do. Furthermore, a few of the stars are not actually single points of light, but are surrounded by luminous gas and dust. Some look like single stars but – under closer observation – are actually double or triple stars. Some are clusters of stars with likewise interesting traits.
So, this time I’ll send you out to look at the moon and then direct your attention at the constellation of Orion. The date is December 28, 2020 and time is 2100 (nine PM). This is Houston and US Central Standard Time, but around this date, if you can find the moon, after sunset, you should be able to find the constellation. Orion is known for its three bright stars in “Orion’s Belt”, as well as its two brightest stars, Betelgeuse* and Rigel. You will see them labeled on the skymap, below.
*You may wonder how to pronounce this. As a young elementary school student, I did too. Nobody around the elementary school knew either and I called it, “bet” (wager) “tel” (as in telephone) “geeze” (as in geezer). With accent on the wager.
Nobody had the knowledge to say otherwise until a college Astronomy professor corrected me. The word sounds just like “Beetle Juice”.
Steve: Sorry, I didn’t know!
Prof: It’s OK Mr. Campbell, nobody does at first.”
Obviously, I was not the first ten-year old Astronomy Nerd.
As you see, I have marked Orion with an arrow from the moon to Orion (that I have apparently drawn with a blue crayon). Also, please note the “A” that I have placed to point out an object to be discussed later.
I will also post a time-lapse photo I made of this region of the sky. It shows about half of Orion. I could show you the whole constellation, but this picture was photobombed by a passing helicopter. You can see that the aircraft had a constant white light and a flashing red one. I could probably take pictures every night for a year and not capture something like this – that happened by accident alone.
This 10 or 20 second exposure was taken in early 2020. Of the three stars in Orion’s Belt, you see two, below the big yellow “2”. I have pictures with all three, but no helicopter. The big yellow “1” annotates Betelgeuse, the red-hued star that is the brightest of all in the constellation and referred to as “Alpha Orionis” – meaning the brightest star in Orion. The big yellow “3” shows you Rigel, the second brightest star in Orion (Beta Orionis).
“Hold on there, Laddybuck!” you are saying, “I can clearly see that Rigel (Yellow Three) is much brighter than Betelgeuse.”
At that particular time, it was, indeed. Betelgeuse is a variable star and pulsates – not as extremely as that red helicopter beacon, but at least enough to make you all say, “Hold on there, Laddybuck!”
And, in fact this particular dimming of Alpha Orionis was unprecedented. Please see chart below:
Betelgeuse Brightness 1965 – 2020
As you can see, Betelgeuse’s drop in brightness was the most severe in many decades. There was actual serious speculation that Betelgeuse was collapsing. When red supergiant stars (of which Betelgeuse is one) collapse, the result is a catastrophic explosion called a Supernova. Is Betelgeuse headed that way? If so, the “Conventional Wisdom” is that – because the star really, really big and is so close to our Solar System, a Betelgeuse Supernova might easily be visible in the daytime…perhaps for months.
I looked up some more recent data and found the answer…Maybe – but not immediately.
Betelgeuse Brightness 9/2018 – 5/2020
You see that the brightness has recovered completely.
However, who is to say that this unprecedented drop will not be repeated? It may take some extreme oscillations to trigger the Supernova.
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.
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.
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.
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.
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! 😉
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! 😉
GoingWalkabout.Blog 