Tag: comet

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.

“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:

“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,

Steve

Comet Update – 6/26/2020

Comet C/20020 F3 (hereinafter mostly referred to simply as “F3”) is now very close to the Sun as viewed from Earth.  Pointing highly complicated and hideously expensive telescopes near the sun is a process to be avoided and so there have been few observations of F3 lately. 

Let me make this perfectly clear – do not try to see the comet at this time when it is near the Sun!

On the other hand, some instruments are specifically designed to look at the part of the sky around the Sun.  One is aboard a probe called Solar and Heliospheric Observatory (SOHO*) that orbits between Earth and Sun in what is called a “halo orbit” around a “Lagrange point” (which has nothing to do with any personal service establishments in the City of La Grange, Texas).

*Note that the acronym should be SHO or SAHO, but SOHO sounded cooler so they use that.

The short story is that SOHO studies the Sun and its atmosphere and comets appear in its field of view from time to time.  F3 has made an appearance there and somebody has measured the brightness about once per day and added that to the COBS (another fractured acronym) database. 

As the comet nears the Sun, it heats up, emits more gas and dust and brightens in excess of distance effect. In the figure below, you can see that the brightness has come close to second magnitude.  Nevertheless – do not try to see it!  SOHO is out in Space and has specially designed instruments – you aren’t and don’t. There will come a time when you can look at it safely and I will be glad to tell you when.

Figure 1: Predicted vs. observed magnitude for Comet C/2020 F3

Below is the SOHO image of the comet for today, June 26.    

Figure 2: SOHO image of Comet 2020 F3 (they call it NEOWISE)

NEOWISE is a project name associated with the Wide Field Infrared Survey Explorer (WISE) which has discovered 28 comets and 313 Near Earth Objects.  That is why Your Humble Narrator does not use “NEOWISE” or any other project or imaging system name as the name of a comet (or other object), like the mundane press so often do.  Because…which one?!  You would think that the SOHO people would realize this…but NO! 😉

Update: I find that the text additions on this graphic are not from the SOHO folks, but added by a third party who shall remain nameless!

In the future, I will quote SOHO graphics myself and add any text for clarification – with attribution to myself alone.

Hasta Luego,

Steve

Comet Update 4/20

   Comets are particularly unpredictable phenomena.  The current case is C/2019 Y4, which has apparently broken up into at least three pieces – which at last sight were drifting away from each other.  It’s visual magnitude has gone from a sudden brightening to 7.8, but then dropped to 8.8 after the break-up and shows no sign of recovering.  This, despite the fact that is nearer to the Sun and the Earth than before.  It is not visible to the naked eye, even in clear, dark skies.  You might find it with a medium amateur telescope.

There is another, more recently discovered comet in the Solar System called C/2020 F8.  It, too has undergone a sudden brightening, but is still a bit to dim to see – even in that theoretical dark, clear sky.  Since it is in the Southern sky right now, you could not see it anyway.

I have made some diagrams of both comets with the JPL Small-Body Database Browser and added some explanatory text.  The planets are all in the same orientations and positions in both.

Figure 1

Figure 2

“So, what next? “, you may ask.  Well, as these comets approach the Earth and Sun – at different rates since the Earth and  Sun are 1 AU apart – they will brighten.  We cam predict the change due to distance alone.  Below is a graph of distances predicted over time for C/2019 Y4 (refer to figure 1).  The data are from the aforementioned JPL Small-Body Database Browser  The graph  was generated by your humble narrator in Excel.

Figure 3

The increase of brightness to be expected (if nothing about the comet itself changes) can be predicted by the total distance involved.  Keep in mind that light spreads out such that a reduction of ½ the distance will result in 4 times the brightness.  Remember that on this stellar Magnitude scale a reduction  of 1 magnitude is the equivalent of more  than a doubling (about 2.5 times) in brightness.  I don’t make these rules, OK? 

This needs some calibration since it calculates only differences.  That calibration is taken from a recent observation as noted on the graph (also Excel) that follows.

Figure 4

The conclusion is that the peak brightness will be still below naked-eye visibility – around May 28th.  Having said that, you will remember that this exercise assumes that the comet itself will not change.  But that’s silly! We just saw it increase suddenly in brightness (far in excess of expectation) and then dim again!  That was from eruptions of  vaporizing ices, that apparently broke this comet into pieces.  I told you these things are unpredictable, did I not?

So, why do this calculation of brightness due to proximity?  Because it is all we can do!  Keep that in mind the next time someone tells you they can predict the climate. 😉

C/2020 F8

The same sort of calculation can be done for this Johnie-come-lately comet that just showed up.  I will skip all the intermediate explanations and go straight to the prediction chart.

Figure 5

You see that the new comet is likely to be brighter than poor old C/2019 Y4.  It will probably become magnitude 6.3 – bright enough to see without binoculars or a telescope – out of city lights, in a dark clear sky -but just barely! 

And, just now we have news of an observation from the Comet Observation Database .  For April 19th (late in the day) the brightness was measured at magnitude 6.8.  You can see the red cross on the graph.  That is, however, one of four observations on that day – the other three were all magnitude 7.5.  To change the whole prediction on a single observation would not be reasonable, so I will wait to do so until a few more observations are made.  Did I mention that these things are unpredictable?

You may ask, “Steve, why did you choose such an uncertain occupation?”

  I did not choose Astronomy. Astronomy chose me. It is actually a hobby because, while I wanted to be Carl Sagan, I found out they already had one.  So, I wound up looking down through the Earth instead, because someone would pay me for that.  Now I have nothing better to do.  Well, I have other things to do – yes.  But, who wants to mow the yard again?

Hasta Luego,

Steve