The night sky is pretty much a mystery to most City Dwellers. The glare of city light drowns out all but the brightest stars – and planets don’t do much better. If you are interested, I can tell you where to look to see these far-off worlds. If you were not interested, you would have stopped reading after the first sentence.
The comet is now well-within visible range – but it will take considerable snakey-eyed concentration to pick it out. More importantly, there will be clear skies on Friday night. I put together this chart with instructions. Print it out and follow instructions. If you need light to see the chart, close one eye while you turn on the flashlight. Or, use an eye-patch to keep night vision in one eye while consulting chart. Professional Astronomers do this, while making corny pirate jokes. 😉
The night sky is pretty much a mystery to most City Dwellers. The glare of city light drowns out all but the brightest stars – and planets don’t do much better. If you are interested, I can tell you where to look to see these far-off worlds. If you were not interested, you would have stopped reading after the first sentence.
There is an “eyes only” comet currently in the Northern Hemisphere skies that will soon be near Mars.
As many of us urban dwellers can attest, “eyes only” means other people can see it.
However, if “Seeing” is good and a good reference body is to be had, binocular-equipped viewers in the worst of urban glare may well be able to pick out the comet in about two weeks and change.
Below is a sky chart from the point of view of Houston observers for February 10, 2023. Since Mars moves slowly through the sky, this will suffice to show the relative positions of the constellations and Mars for the four-day period I am analyzing here. The chart is calculated at 2200 (8 PM CDT) and everything will be moving to the West (right) until things start setting in the West, around 1 or 2 AM. All images credit: Heavens-Above.com
Once you have located Mars, get out those binoculars – or use those keen eyes if you are in dark skies. Use the dated charts below to find where to look for the Comet.
Contact me with any questions: steve.campbell@reagan.com
The night sky is pretty much a mystery to most City Dwellers. The glare of city light drowns out all but the brightest stars – and planets don’t do much better. If you are interested, I can tell you where to look to see these far-off worlds. If you were not interested, you would have stopped reading after the first sentence.
So, at this point, I know my audience.
Comet 2021 A1 – Leonard Dec 20, 2021
Leonard is even brighter – in fact much brighter – tonight. The current magnitude of Leonard is +2.3 (the smaller the number, the brighter – the comet was +4.6 yesterday and Saturn is +0.23 – VERY bright by comparison) so in the city, the Comet is visible and would be still better seen with binoculars.
You may have heard the expression “by an order of magnitude” – well this is over two orders of magnitude – OK?
Once again, do not use telescopes or binoculars to view the Sun – blindness will result! I said “after sunset” so you should be OK if you listen to me. 😉
As is usual in these cases, the comet gets brighter not only because it gets close to the Earth. It also gets brighter because it gets closer to the Sun. The third brightening influence is the material that the closer sun vaporizes. That stuff makes a cloud around the comet and is it also partially blown away by what is called the Solar Wind – in a comet’s tail.
Figure 1, above shows the location to view, which is conveniently close to Venus, which is the brightest thing in the sky. If you can see the Planet, you should be able to see the comet – although you may need those binoculars to do so.
The sky is currently “mostly clear” (look-out-window method) in Houston at 3:22 PM. Sunset is at 5:26 PM. These next few days are literally the last chance to see Leonard, as it is on a hyperbolic orbit – which is a nerdy way to say that it will never return to the Solar System. (Please see figure 2 below)
For readers not in the Houston area, just look for Venus (and Jupiter for orientation) and use the chart in Figure one above to find the comet. We are lucky to be able to have the two brightest objects in the sky (now that the moon is not around in the early evening) as our reference points.
The night sky is pretty much a mystery to most City Dwellers. The glare of city light drowns out all but the brightest stars – and planets don’t do much better. If you are interested, I can tell you where to look to see these far-off worlds. If you were not interested, you would have stopped reading after the first sentence.
So, at this point, I know my audience.
Comet 2021 A1 – Leonard
There is another “Eyes Only Visible” comet to be seen in the Southwestern sky, just after sunset. The current magnitude of Leonard is +4.6, so in the city, it is only just visible and would be better seen with binoculars. Once again, do not use telescopes or binoculars to view the Sun – blindness will result! I said “after sunset” so you should be OK if you listen to me. 😉
As is usual in these cases, the comet gets brighter not only because it gets close to the Earth. It also gets brighter because it gets closer to the Sun. The third brightening influence is the material that the closer sun vaporizes. That stuff makes a cloud around the comet and is it also partially blown away by what is called the Solar Wind – in a comet’s tail.
Figure 1, above shows the location to view, which is conveniently close to Venus, which is the brightest thing in the sky. If you can see the Planet, you should be able to see the comet – although you may need those binoculars to do so.
We have had very cloudy weather here in Houston (today, Dec 19) is “Mostly Cloudy” at 4 PM, changing to “Cloudy” around Sunset at 5:26 PM. Tommorow at Sundown the prediction is “Mostly Cloudy” and the comet will have moved slightly relative to Venus. These next few days are literally the last chance to see Leonard, as it is on a hyperbolic orbit – which is a nerdy way to say that it will never return to the Solar System. (Please see figure 2 below)
Figure 2. Comet Leonard is diving through the Solar System, never to return.
For readers not in the Houston area, just look for Venus (and Jupiter for orientation) and use the chart above to find the comet. We are lucky to be able to have the two brightest objects in the sky (now that the moon is not around in the early evening) as our reference points.
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.
“Wola.
Spotted it now with a Nikon 10-22×50
Still hard, but knowing where to look is key.
Thanks…”
I have searched for a definition of “Wola” and can only come up with a Polish district:
I would continue to search, but I am busy now making Uber commerce at an accelerated rate to fund the difficulties chronicled inUber Ally – where I owe an update to my Norwegian colleague.
This Comet update is also overdue and I hasten to publish same.
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:
“WE SAW NEOWISE!!!!!
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.
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
Figure 1: Orbit of Comet 2020 F3 generated by JPL Small Body Database Orbit Diagram Widget. Augmented and annotated by your humble narrator.
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.
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
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.
*Doh!
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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”.
However…
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?) 😉
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