Author: Going. Walkabout

Uber Alley – Frozen Palms

Published April 18, 2021

Many of you in the Road Trip Interest Group*  live in Houston and experienced “The Freeze” of February 2021.  One thing you cannot have failed to notice is the dead palm trees that are sprinkled like brown confetti in every part of the Houston.

*My email list for article alerts.  Go to “Contact”, put Road Trip in the subject line and include your email address.  You’ll get a Blind CC message with a short description and link once every couple of weeks, max

Figure  1:  Variations of this scene are repeated thousands of times across the Greater Houston Metropolitan Area.

   The devastation is frequently in commercial zones, especially at Tropical Wannabe bars and restaurants.  I do not dispute that these trees do supply a pleasant view while partaking of libation.  However, it has become obvious that such plants are not appropriate for the climate, even though they may persist for years.   This place may have been vacant at the time.  I doubt if insurance would pay off for the landlord.  Such trees are an asset in a patio bar and the cost to remove them will be substantial. 

Precious few of these plants will survive, but I have seen a few, especially where the plants and trees were close to buildings or where the residents had actively protected the subjects.

A good example can be seen in figure 2, below.

Figure 2:  These houses are a few blocks apart in the same neighborhood.  Note the vivid difference in outcome.  I take the liberty of warning young folks that the “drop-light” strategy requires incandescent light bulbs – NOT LEDs!   Such attention to the trees in figure one would obviously be impractical. 

There is a big stand of (dead) palms at I45 South and Broadway.  A sad sight, but magnificent in its scope! I’ll try to get by there for a photo-shoot.

I too, worked hard to protect our crop of Aji Amarillo Picante.  Alas, all was in vain!

Hasta Luego,


Near Earth Asteroid 2021GW4

Published April 11, 2021

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.

Ex Sciencia, Trivia


Urban Astronomy April 6, 2021 (about 0630)

Published April 5, 2021

The Earth has gone around the Sun again and Jupiter is in the morning sky once more.  The Urban Astronomy Cursor (AKA, The Moon) is again indicating that planet around 6 to 7 AM.  Shortly thereafter the Sun rises.  Readers will remember that the “last time around” Jupiter and Saturn were close neighbors.  Now more distant, they are. You will find Saturn at a 45 degree angle up and to the right from Jupiter.

The waning crescent Moon points out Jupiter and Saturn.

Harrison Schmitt – Geologist & Lunar Astronaut

Published March 9, 2021

I have seen this impressive speaker at the Lunar and Planetary Science Conference at least twice.  He strikes me as near to a “genius” as is possible for a human being.  I seem to remember that someone said, “Genius is one percent inspiration and 99 percent perspiration.  Certainly that will describe this Apollo 17 Astronaut and the first Geologist to stand on the Moon. 

As the video linked will reveal, he spent his time traveling to the moon looking back to analyze the weather of the Earth as it receded from the Moon-bound spacecraft.

I was not at this particular LPSC conference, but I am glad to have the video to appreciate the talk given by Schmitt, who never fails to impress, whenever I have seen him in person.  Among other subjects, Schmidt discusses:

  • Refined navigation – just a few orbits before –  that allowed a precision landing.  
  • Very plain, abundant and visible evidence of the lunar landing from Lunar Orbiter satellites decades after the landings – including rover tracks, footprints and long-lasting American flags that still cast shadows.
  • Body work on the Lunar Rover and why the lunar rover could not get stuck. 
  • Engineering challenges for future Moon work including space suit design and “roadwork”.
  • Sampling techniques and results including the famous “Orange Soil!”.

Figure 1:  Harrison “Jack” Schmitt December 1972 (left) and March 2017 (right)

After that is a lot of arcane Geological detail and the average viewer may be forgiven for fast-forwarding.  My readers, however, are above average and should be interested.

After that are the questions and that is required viewing, readers! 

Schmidt is very good at explaining this stuff.

No description of Lunar Geology* would be complete without a reference to Eugene Shoemaker, who was the premier enthusiast on that subject and would have been the first Geologist on the Moon, had it not been for a medical disqualification.  The first question to Schmidt (around 59 minutes) was about Shoemaker and the reply was, “I wouldn’t be here were it not for Gene Shoemaker”.  Schmitt was working for Shoemaker, who encouraged him to apply for the Moon program.

*The proper term in Selenology, but that term is rather obscure and awkward.

The very next question is about Helium 3 – of great interest to this reporter – that almost certainly is to be found on the Moon.  This is a substance that does not occur naturally on Earth and could make Fusion power practical. Video should appear below:

Schmitt was about 82 at the time of this lecture and had not lost his quick wit and sense of humor – nor his pitching arm (near the end).

Uber Alley – The Artyard

February 22, 2021

A lot of Houston passes me on my random-walk car journeys around the City and the surrounding lands.  The new phone has refused to allow me to transfer photos off of it as a USB device with another drive letter – like the previous phone did so handily.  So, I resort to a ridiculous method of sending emailed attachments to myself on the phone and receiving same on the computer.  It works.

I have passed this art storage area once and missed the chance to take photos.  I found it again and I know where it is now.    Probably they have security cameras, but I have decided not to publish its address because the place looks vulnerable.

The abstract conductor very much resembles an abstract cellist I have seen on public display near Jones Hall, I think.  The Charlie Chaplin – stretch version – seems to be about 20 feet tall.

 The many busts in this second photo resemble some similar art you might see off US 59 southbound .  I saw a block-sized green low-rise building near here, with bars on the painted-out windows, that was labeled as “Studios” – I don’t think they meant apartments. That may be associated with this place.  Are these works produced on speculation (and awaiting sales) or were they commissions that are not yet emplaced?  No idea.

Hasta Luego,


KBO 2014 MU69 – Post Conference

Foreword January 2021

   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 at

   This is the sequel to my earlier post Kuiper Belt Object 2014 MU69

   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


  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.

See NASA video about MU69/Arrokoth

Ex Sciencia, Trivia,


Kuiper Belt Object 2014 MU69

Published Jan 16, 2021

Kuiper Belt Object 2014 MU69

Preface (January 2021): 

   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 at

   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

   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 I and 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).

REX: (Radio Science EXperiment) Measures atmospheric composition and temperature; passive radiometer.

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.


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.

To Be Continued…


  1. New Horizons Spacecraft:
  2. Voyager Memory and Data Rate:
  3. New Horizons Mission: Dawn and New Horizons Missions Sept. 3, 2015 Lunar and Planetary Institute, Lunar and Planetary Institute September 3, 2015   NASA’s Exploration of Ceres and Pluto: An Update, Dr. Paul Schenk
  5. Planetary Radio: Countdown to Ultima: Alan Stern and New Horizons 12/26/2018
  7. Tholins:

Near Earth Asteroids – 2021 AH

Posted January 4, 2021

Other Near-Earth Asteroid Stories (Click and scroll down)

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.  😉

2021 AH

Hasta Luego,


Urban Astronomy – The Scale of the Solar System

Posted Dec. 29, 2020

I read regularly at (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.


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!

Hasta Luego,