Tag: comets

Comet Update 7/31/2020

7/31/2020 Comet 2020 F3 is now receding back into the distant reaches of the Solar System.  As yet, however, it is still closer to the Earth than the Sun and closer to the Sun than the Earth is.  This should make one appreciate just how rare and fleeting is the opportunity to see these events with “Eyes Only”. 

In point of fact, I – your humble narrator – did not actually see this comet without the use of binoculars.  And even then, it was only a fleeting glimpse – out of the corner of my watering eye (1).

“Above the planet on a wing and a prayer
My grubby halo, a vapour trail in the empty air
Across the clouds I see my shadow fly
Out of the corner of my watering eye
A dream unthreatened by the morning light
Could blow this soul right through the roof of the night”

That was on July 24th when a rare cloudless Northern sky presented itself and I was awake at the proper time.  I attempted to show this to all the immediate   family.  For the record, it is painfully difficult to describe how to point the binoculars to another person, despite placing the student in the recently vacated footprints of the Astronomy Nerd and the use of tree branches as reference points.  And even when it works, the family member is underwhelmed by the dim little streak that is seen.

Figure 1:  The “Standard” graphic updated for July 30, 2020.  Green series: calculated for distance alone.  Blue series: Daily average of Observations (COBS)

In  figure 2, below is seen the orbital configuration of the comet as of July 31st.  The comet – known by the mundane press as ”NEOWISE”   (which is the name of the space probe that discovered the comet, modified by its extended mission prefix) is actually named only “C/2020 F3”

Figure 2: Orbit Diagram of C/2020 F3 as of7/31/2020

A Norwedian collegue and reader was also able to spot the comet – despite being so far North that he had to wait until a half-hour before Midnight for the sky to be dark enough.  As he pointed out, that left him with about one hour of observation time until the sky woould be brightening again.


Spotted it now with a Nikon 10-22×50

Still hard, but knowing where to look is key.


I have searched for a definition of “Wola” and can only come up with a Polish district:

“First mentioned in the 14th century, it became the site of the elections, from 1573 to 1764, of Polish kings by the szlachta (nobility) of the Polish-Lithuanian Commonwealth

The Wola district later became famous for the Polish Army’s defense of Warsaw in 1794 during the Kościuszko Uprising and in 1831 during the November Uprising, when Józef Sowiński and Józef Bem defended the city against tsarist forces.”

I would continue to search, but I am busy now making Uber commerce at an accelerated rate to fund the difficulties chronicled in Uber Ally   – where I owe an update to my Norwegian colleague. 

This Comet update is also overdue and I hasten to publish same.

Hasta Luego,


Comet Update 7/19/2020

Comet 2020 F3 is creeping up in the post-sunset sky.  On July 14, I may have seen it dimly through the distant haze – in moments when the nearer and opaque clouds drifted out from in front.  In those 20 seconds, I saw what could be the nucleus of the comet through a pair of binoculars.  Any hint of a tail was not to be seen.  But, the sky map doesn’t show anything else in that part of the sky that would be bright enough to show through the haze.

I don’t call out family or friends for these desperate attempts at observation.  Mostly because – when asked to point out this astronomical wonder – I am forced to say,

“See that cloud over there?”

“Yes, I see it.”

“The comet is behind that cloud.”

“How do you know?”

“Because that’s where the sky map says it should be.”

“I mean, how do you know for sure?”

“…I don’t.”

That’s why astronomers have been considered lunatics – for centuries.  You may think I’m joking, so look up a Danish fellow named Tycho Brahe.  (Teak – oh  Bra-hay)

Figure 1:  The “Standard” graphic updated for July 19, 2020.  Green series: calculated for distance alone.  Blue series: Daily average of Observations (COBS)

Figure 2:  Sky map as found at the July 14 link on the previous update.

Figure 3: Sky map as modified by your humble narrator to reflect actual field conditions.

On the next day, July 15, the forecast was for clear skies after sunset, but I made the Rookie Mistake of not setting an alarm and slept through the opportunity.  Astronomers have to set their schedule by when the observation presents itself. 

As Shakespeare wrote, “It is the stars, the stars above us, govern our condition.”

Shakespeare also wrote, “The fault, dear Brutus, is not in our stars, but in ourselves”. 

So, I have no excuse for not setting the alarm.

July 16-19, 2020    9:00 PM  See that cloud? The comet is behind it.

In a message from my long-time reader and cousin:

My friend is in OK right now. I gave her all the info last week. I just got this message:


It was so awesome!!  I was so excited like a kid walking into Disney World!! 
It took us awhile to see it but it has to be very dark and we were out in the country..
The tail was very clear and all the stars around it just highlighted the beauty…”

My reply:

I am happy to hear that someone has seen this comet.  It is starting to dim now as it recedes from the Sun.  It has yet to make its closest approach to the Earth, but any brightening by proximity is more than canceled by a more distant Sun and a calming of gas and dust emissions due to less Solar heat and radiation.

Sky maps (from  Spaceweather.com): July 18, 19, 20.

And a 3 ½ minute exposure by James W. Young – also from spaceweather.com

Figure 4 Three and ½ minute exposure (tracked – or the stars would smear) by James W, Young – from Spaceweather.com

Clear Skies!




COBS:  https://cobs.si/analysis

Comet Update 7/3/2020


Comet 2020 F3 is still in one piece and still brightening.  As in the previous update it is rounding the Sun in the fast, sharp curve that includes the Perihelion (closest approach to the Sun).

See Figure 1, below

C2020_F3_Orbit_July 2
Figure 1:  Orbit of Comet 2020 F3 generated by JPL Small Body Database Orbit Diagram Widget.  Augmented and annotated by your humble narrator.

Spaceweather.com features a four-day movie of the comet’s appearance in  the LASCO instrument onboard the Sun-watching SOHO probe.

There were at some observations, after the comet left SOHO’s field of view.  Seven are now documented in the COBS database as bright as magnitude 1.0  – comparable to the brightest stars in the sky.

See it also in the now “standard” graphic for my updates- below.

Figure 2:  The Standard Graphic.

After the SOHO data (red circle) are “conventional” telescope observations and you might think that a decline is happening.  Don’t take that to the bank, because these observations are from telescopes looking just above the horizon and just before dawn.  That is a lot of atmosphere to look through and a lot of twilight interfering.   Estimates of brightness of the comet might be inexact.

Note that:

The “Calibrated Prediction” (green dots) has about July 17th as the peak brightness.  That is based solely on the distances (Sun to Comet to Earth) and assumes that the comet reflection characteristics never change.  That is – of course – never true of comets when they warm up near the sun – emitting gas and dust chaotically.  So, why do the “prediction”?  Because then we know how much of the brightness variation may be attributed to distance alone.  We can take that effect out to study the changes in reflection characteristics…including periodic variations that must be due to rotation. 

If this sounds like an “inexact science” – good!  All Science is inexact!   However, a good Scientist can give you some idea of just how inexact his science is.   😉

Challenging the Dawn

Oscar Martín Mesonero of Salamanca, Spain, also saw the comet in morning twilight.  See his photo below (also from Spaceweather.com)

Figure 3:  Mesonero’s photo of C/2020 F3

The comet is here seen as more-or-less “head on” and seems to vaguely show a bifurcated (two part) tail.  That is not unusual as gas particles may be ionized and affected by the Sun’s magnetic fields and solar wind.  The dust particles tend to stream out behind the orbital direction of the comet’s path, while still blown around by solar wind.  Sometimes the two line up as viewed from Earth, other times, not so.

Hasta Luego,


Comet Update 5/19/2020

Comet 2020 F8 has dimmed from its last outburst and is now just barely qualified to be “eyes only visible”.  I call it that only in the abstract since I have attempted to spot it several times with binoculars without success.  I live on the west side of Houston and the place where the comet is theoretically visible is in the northeastern sky – which is awash in city-light at best – just before dawn.  My carefully chosen location is down south on a road that leads to Brazos Bend State Park where I was a volunteer telescope operator at the George Observatory.

You may ask why I did not use that telescope to view the comet.  It is that the public viewing program at “The George” was suspended late last year for renovations to the observatory and museum facilities.  It was all set for a grand re-opening when the current disruption concerning the Communist Chinese Xi Jinping Virus began.   

My attempts at viewing the comet took place on mornings this past week when skies were allegedly clear.  None were successful – due mostly to the aforementioned urban skies. The path of the comet is from the southern extreme of the Solar System – crossing into the northern skies – where it is now found – and exiting back to the south.  Because it is closer to the Sun now, it can only be seen in the early morning.  Later this month it will appear in the evening sky just after sunset.  More on that later.

The diagram in Figure 1 shows the current positions of the comet and Earth.  Mercury and Venus are seen but not labeled.  I dotted the comet’s path when it occupies the southern part of the Solar System.  With a considerable imaginative effort (and taking into account the direction of Earth and the comet), you can understand why it only appears in the early morning sky now and will appear just after sunset later. 

Figure 1: Comet’s path through the Solar System. Orbits of Mercury and Venus are shown but not labeled.

Figure 2 is the updated light curve and shows the decline in brightness.  Since it has now passed its closest point to the Earth, we could expect it to dim – if it were not still approaching the Sun.  The Sun will illuminate the comet more – and heat it, which may induce another outburst of brightness.  

Or…it could fall apart and disappear.  No guarantees, you understand. 😉

The observations are being “handed over” from southern hemisphere observers to those in the north.  That gap near the 15th is a result.  There were single observations each day, but so far from the norm that I did not bother to plot them.

Figure 2. Predicted “distance only” brightness and actual observations

Hasta Luego – Steve

Comet Update 4/30/20

Comet 2020 F8 is now visible with “eyes only”.  But not from the Northern Hemisphere.  I hasten to explain that the “crosshairs” appearing (below) on the brighter stars are artifacts of the telescope construction – diffractions caused by the mounting bracket of the secondary mirror.

Figure 1:  Taken by Gerald Rhemann on April 27, 2020 @ Farm Tivoli, Namibia

This is when the comet was at about magnitude 6.3.  As of this writing, 2020 F8 is showing at magnitude 5.3.  You will recognize the graph below as my calculation of brightness change due to total distance (Sun/Comet/Earth) with the average daily observed magnitude.  I warned you that comets can’t be predicted with simple models like that and now you see what I meant.

Figure 2.  The “distance only” prediction and the observed (daily average) brightness

Again, the differences are due to eruptions of gas and dust, making a much more reflective target.  The comet now qualifies for “eyes only” visibility.  It is still something for which you would need to take a trip outside your sophisticated urban environment.  But don’t even bother because – except for my readers in the Southern Hemisphere – it is still below the southern horizon.  I am working on some sky charts for Lima, Peru. But that still requires a road trip to a dark sky.  There may be something for you city dwellers later.

Figure 3

Update May 5: In Lima, the comet is in the Eastern sky just before dawn (unfortunately looking right across the well-lit city) at about 25 degrees altitude. The sun will be rising soon so here is the standard warning: Do not look at or near the Sun with binoculars or a telescope! Blindness may result.

There is also a meteor shower this morning, coming out of the West East and streaking across toward the city ocean.* Also, look for Mars, Jupiter and Saturn together in the Southeast. There are conflicting weather reports. One says mostly clear. If that works, “Sigrid, te quito la bruma Limeña!”. Otherwise – same as usual.


Use the reply window below for questions. If you don’t see the reply window, click on the title at the top of the article to make it appear below.

Hasta Luego,


Comet Update 4/26

Comet C/2019 Y4 has broken into pieces that are scattering and fading in brightness despite being closer to the Sun and Earth.  I will include a Hubble Space Telescope photo here:

Figure 1

It will not be a “Great Comet”.


Comet 2020 F8 is now visible in a small telescope or binoculars and will probably be – at the very least – visible without such aids very soon.  Below is a recent image from Universetoday.com

Figure 2

But, you won’t see it now because it is in the Southern sky and is being observed from New Zealand and Australia and other points in the Southern Hemisphere.  It will arc over the Northern sky soon.  In the previous update, I graphed the brightness to be expected due to distance alone.  You can take this as a prediction of 6.3 as the peak magnitude. But, we all know that is almost certainly wrong – because we don’t have enough information. I have added the daily average observed magnitude (orange dots) in Figure 3, below.

Figure 3.

The observations are, indeed following the prediction – somewhat.  The differences can be attributed to eruptions of gas and dust, but also to the comet’s rotation.  In college, I learned a method of analyzing sparsely collected observations to detect periodic changes.  It goes something like this:

We cannot monitor objects in telescopes with enough resolution in time to detect a periodic variation along one cycle of rotation or pulsation.  However, since we expect the oscillations to be more-or-less uniform over time, we can collect points from different oscillations, over an extended period and graph them as a single cycle. 

But this requires that we know the period of the cycle.  Astronomers have been historically starved for data and come up with some desperate solutions.  In this case, we can try every possible period of oscillation, put the resulting data on graphs, and pick the one that looks like we think it should for a single cycle.  In the olden days, this laborious amount of calculation could be out-sourced to graduate students or assigned as homework for undergraduates. If you want to imagine doing such calculations “by hand” go ahead.  Me, I don’t have to use imagination because I did it – a few times.

The observations have a time associated with them.  We establish a “zero point” and calculate a time value for each magnitude.  Then each observation time is divided by the trial period.  That leaves a fraction that is the position in the single “combined” oscillation we intend to graph.  Then we change the trial period and repeat – a lot.  Below is a “perfect” theoretical graph to be kept in mind while looking through all the trial graphs.

Figure 4.  Ignore the numbers, which are “made-up” anyway.  Concentrate on the shape.

And before you ask “why didn’t you use a computer at UT in 1976, Steve?”, I should tell you that in the 70’s, a computer with a tiny fraction of your telephone’s capability was a huge machine in a large room attended by several “operators” who scheduled calculations on that hideously expensive device for days in advance. The data and the programs (apps) were read in on punch cards and the output was printed on green-and-white paper.  What “memory“ was available held the simple operating system and your bare-bones program and input data for the time it took to complete the “job”.  Then your data and program were immediately replaced with the next job. No time was available for undergraduate homework.  

Now we have Excel spreadsheets instead of graduate students or IBM 360 “mainframes”.  The needed calculations and a graph on the screen for one trial period is accomplished in a split second with a single click.  The graph below was selected as “plausible” after 291 clicks.  This indicates a period of  four hours, 51 minutes. 

Figure 5

The points plotted come from 74 observations over 14 days.  I should mention that these were not the “raw observations” but were adjusted to remove the distance-related brightening (that green  curve in Figure 3).

This was the “best-looking” result, but there were other “candidates” at six hours, seven minutes and at eight hours, 10 minutes.  Nothing even close to “plausible” was found after that, up to and including a 30-hour trial period.

So, if you hear later that the comet has been determined to be rotating at a period like any of those – remember that you heard it here first!  Otherwise, well I was wrong.  Science has a long history of being wrong, so that’s OK.  The important part is to not insist on your theory in the face of contrary evidence and accept that you were wrong.  (Are you listening, Global Warming Devotees?) 😉

Use the reply window below for questions. If you don’t see the reply window, click on the title at the top of the page to make it appear below.

Comet 2019 Y4 4/14/20

April 14, 2020

The comet is breaking up!  I will attempt to imbed this image and its source.  Don’t be surprised if you see it more than once.

Figure 1: Y4 is breaking apart


Before you write me to say, “Why didn’t you photograph the comet, Steve?” – this image is from a telescope with 8 times the light-gathering power of mine.  Add to that, the fact that they took 120 second exposures…twenty of them.  To do that they had to track the comet as it moved through the background stars that make the streaks you see.  Their telescope is guided by sophisticated computerized servos, while my ‘scope is on a mount made from a plywood box and is guided by “pushing with your hand”.  Then they stacked those 20 photos together to make this image.  These are professional Astronomers in a Swiss observatory while I am just a guy in a driveway in Houston.

The pieces are estimated to be spread out over more than two thousand miles.  This is not unprecedented and if you want to learn more try looking at this paper:  Split Comets   H. Boehnhardt Max-Planck-Institut für Astronomie Heidelberg

I warn you that this is what Literature students call “a bear”!  But my preliminary read tells me that the comet fragmentation could pre-sage a disappearance or it may be associated with sudden eruptions of activity that result in a brightening.  A long-winded way of saying “Anything could happen”, this is. 😉

There are many reasons a comet might break up but the main two in this case (in my humble opinion) are probably thermal stress and gaseous eruptions of sub-surface ice bodies.

Update: A recently discovered comet in the Southern sky has undergone an “outburst” and is already as bright as Y4. It is not yet in the databases, so no cool diagrams, yet. Details in the next post.

More Later,


Comet 2019 Y4 04/11/20

Homepage  5 Decades, 5 Comets

 By Steve Campbell     April 11, 2020

Comet 2019 Y4 (hereinafter called simply “Y4”) is still approaching the inner Solar System and still being observed.  It occurs to me that I have not posted an actual image of this comet, So, that will be figure 1:

Figure 1: This is Y4 as of March 21, 2020. It comes from a 16 inch telescope, see link below.

 I promised a diagram to explain Y4’s path through the Solar System.  To quote my previous comment:

“ I’ll include a diagram in the next update. But, for now, imagine yourself as very small and standing on an old-school LP record. The gaps between songs are the orbits of the planets. You are on the third gap and the comet is at the 4th gap but high above the LP. It will come in past all the rings and dive into the record inside Mercury’s orbit (1st gap) on May 30th. It will emerge on the bottom side and make a similar, but mirrored, exit path. It is moving at a tremendous velocity because it has been falling toward the Sun since about 1844. -Steve”

With this verbal imagery and the diagram below (figure 2), I hope the situation is well-explained.

Figure 2: The path of Y4 through the Solar System

I have plotted the position of the Y4 on March 13th and April 10th.  Those dates were chosen from the a magnitude chart because the comets was at the same brightness on both.  In the meantime, the comet has moved much closer to the Sun.   Please see the magnitude chart below and pick up the story below that.

Figure 3. Note the maximum brightness observed on March 13 the and April 10 are about the same at about magnitude 8.7

Comets don’t shine like stars, they only reflect the sunlight that shines on them.  Before I go further, please remember that magnitude is a smaller number for brighter objects.

If the comet were unchanging, then the fact that it is closer should mean that the brightness would increase from magnitude 8.7 to about 7.9 (just take my word for that:-).  Clearly, something did change, because the comet brightened too quickly and then dimmed again.  What happened is why comets are so unpredictable. 

The comet body, warmed by the sun will begin to “evaporate”.  Frozen gasses are vaporized and form a gas cloud around the “nucleus” and are blown away by the radiation from the Sun and the rush of sub-atomic particles called the “solar wind”.  That is what makes the comet’s “tail”.  The bigger ball of gas reflected more light and so the brightening. 

The dimming?  Maybe:

  • The vaporizing gas may have “unglued” the body of the nucleus and it started falling apart.
  • The stuff beneath the frozen gasses is darker rock and reflects less light.
  • The ice that was volatile at this temperature has all vaporized.

What will happen next?  Maybe:

  • The comet may fall apart completely and disappear.
  • Less volatile ices may vaporize when the comet is closer – and therefore hotter – and that will renew the brightness

That last option at least leaves open the possibility that the show is not over.

Hasta Luego,


Comet 2019Y4 4/7/20

Update on C/2019Y4  April 7, 2020

(See all updates by clicking on the comets icon at the top of my home page)

Readers may remember that I wrote about this comet:

“As it nears the sun, it will brighten quickly.  It could become the brightest object in the sky.  However, it may just break apart and disappear.  See the text on figure  1 at This link

So, you were warned – and that last part may well be happening now.  Below is a collection of all photometric (CCD) observations of Comet 2019Y4 from March 7.  Below that is a graph of the distance from the comet to the Sun (orange) and from the comet to Earth (blue) for the same period.  The distances are in Astronomical Units – the distance from the Earth  to the Sun – about 93 Million miles

You see that:

* The comet was brightening until about April first.  Then it declined rapidly until today April 7th.

* In that time, it has gotten closer to the sun, which illuminates the comet better than before and closer to the Earth – where we should see it brighter than before – even without the additional illumination by the Sun.

* See the Conclusions below  the charts

  • One expects a comet to lose mass as it is blown away by the solar wind – that is what makes the “tail”. That would cause a dimming due to a smaller reflective surface and smaller “gas ball” surrounding.  This will be offset by brightening by being nearer to the Sun and Earth.
  • In this case, the dimming is faster than the brightening due to being nearer. The comet is probably wasting away quickly – on its way to disappearing for good.
  • But, I could be wrong. 🙂
  • Hasta Luego, Steve

P.S. If you have any questions please use the comments section (Leave a Reply) below and I will answer for all the readers who may have had the same question. Thanks SBC

Comet 2019Y4 April 3

April 3, 2020 – update on Comet 2019Y4

The weather has been even worse than usual for astronomy.  Don’t misunderstand – around here, there are just awful conditions for viewing at the best of times.  But cloudy weather has been unusually frequent lately.  The comet is still not very bright, in an area of the sky that is devoid of any bright stars for guidance and in a direction that is particularly afflicted with trees and city-light.  Nevertheless, I have attempted to spot the comet with binoculars several times – without success.

Attempting to photograph what could not be seen visually of Comet 2019 Y4, I am struggling with an unfamiliar DSLR (digital single lens reflex) camera.   Just the camera on a tripod and guessing at various settings of exposure, “film” speed, focus and aperture.  No, I didn’t see the comet.  I was barely able to detect any stars in the city-light washed-out sky.

One thing that stood out was some much more concentrated and colorful points of light.  I wondered what these could be since they were far to point-like to be anything in the sky that was not even properly focused.  Despite that these were intense and focused bits of light.

Figure 1: In the blue circle, a star. Doubt me if you must, but it is there – about half the diameter of that blue circle. In the red circle, an unexplained cluster of bright pixels

Figure 2: Zooming on a longer exposure frame, this is a star, blurred by incompetent focus and unstable air.

The bright spot in the red circle  of figure 1 – what could make such undeniable point-like events?  The answer came back – after considerable snaky-eyed concentration – these must be traces of cosmic rays.  As it turns out – I was right.  The lens of the camera has nothing to do with these images.  The high-energy particles pass through the camera body from any and all directions.  If at a low angle to the “chip”,  the image extends to an oblong shape, like the examples below.

Figure 3. Left: the example of a cosmic ray trace in a DSLR camera at the website found by googling cosmic rays. Right: Extreme zoom, on what I found on my DSLR during my attempts to photograph the comet.

The irony is that the comet, which is right here in the Solar System – along with stars that are in the visible “neighborhood” are so elusive, while cosmic rays, which may originate half-way across the universe, are showing up  clearly as “volunteers”

It has become clear that I will have to make a trip out to a dark sky location to see this comet.  That may take a while, so I will hone my skills with the binoculars and camera, in the meantime.

 Others are not so unfortunate in their efforts to see this comet. Collected observations of the comet show that it has dimmed in the last week.  Please see figure 4.

Figure 4. It can be seen that the brightness fluctuates, but is in a down trend in the last few days.

Hasta Luego,