## APOD: Tails of Comet ZTF (2023 Jan 09)

APOD Robot
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### APOD: Tails of Comet ZTF (2023 Jan 09)

Tails of Comet ZTF

Explanation: Comet ZTF may become visible to the unaided eye. Discovered early last year, this massive snowball has been brightening as it approaches the Sun and the Earth. C/2022 E3 (ZTF) will be closest to the Sun later this week, at which time it may become visible even without binoculars to northern observers with a clear and dark sky. As they near the Sun, comet brightnesses are notoriously hard to predict, though. In the featured image taken last week in front of a picturesque star field, three blue ion tails extend to the upper right, likely the result of a variable solar wind on ions ejected by the icy comet nucleus. The comet's white dust tail is visible to the upper left and much shorter. The green glow is the comet's coma, caused by glowing carbon gas. Comet ZTF is expected to pass nearest the Earth in early February, after which it should dim dramatically.

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Ann
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

APOD Robot wrote:
In the featured image taken last week in front of a picturesque star field

Yeah, right! That link takes us to an open cluster in the Small Magellanic Cloud. As if Comet ZTF has visited the Small Magellanic Cloud. Well, I can do better, I think. How about this image to illustrate the concept of a picturesque star field?

But then APOD does much better. The Comet ZTF link is great, because it takes us to a page where we can follow the comet live and see exactly where in the sky it can be seen at the moment when we look it up. This is where the comet is as I am writing this:

Comet ZTF position 9 January 2023 6 55.png

The bright star is Kappa Corona Borealis, a 4.8 K0III-IV orange star of some 10 solar luminosities at a distance of some 100 light-years.

The C/2022 E3 (ZTF) link is also good, because it takes us to a Wikipedia page about the comet. It features a star chart showing the path of Comet ZTF, albeit annotated in German.

The unusual green color is likely due to presence of diatomic carbon, chiefly around the comet's head.
The unusual green color? How many color images of comet comas has the writer of the Wikipedia page seen?

The Wikipedia writer redeemed himself somewhat by writing this:
The C2 molecule, when excited by the solar ultraviolet radiation, emits mostly in infrared but its triplet state radiates at 518 nm. It is produced by photolysis of organic materials evaporated from the nucleus. It then undergoes photodissociation, with lifetime of about two days, therefore the green glow appears in the comet's head but not the tail.
Ann
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MarkBour
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Another field of stars for you, Ann.
ForAnn.jpg
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Mark Goldfain

Ann
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

MarkBour wrote: Mon Jan 09, 2023 6:29 am Another field of stars for you, Ann.

Maybe these blueberries are tiny rocks on Mars?

Then again, maybe the blueberries are galaxies?

Huan Yang et al. wrote in The Astrophysical Journal:

These blueberries are dwarf starburst galaxies with very small sizes (<1 kpc) and very high ionization ([O iii]/[O ii] ∼ 10–60). They also have some of the lowest stellar masses ($\mathrm{log}(M/{M}_{\odot })\sim 6.5\mbox{--}7.5$) and lowest metallicities ($7.1\lt 12+\mathrm{log}({\rm{O}}/{\rm{H}})\lt 7.8$) of starburst galaxies.

I understand every word of the quote I just gave you, and I can explain the mathematical formulas perfectly! Of course!

Ann
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orin stepanek
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Comet-2022-E3_Eliot-Herman_ECP_New-Mexico_Dec-12-2022-e1671563148468.jpg
A beautiful Comet arioves! I hope it gets visible to the naked eye!
q065n6zy2r401.jpg
Kitty cat; did you try to climb that tree?
Yah; just walk away nonchalantly; as if nothing even happened!
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Orin

Smile today; tomorrow's another day!

bystander
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Ann wrote: Mon Jan 09, 2023 7:39 am
MarkBour wrote: Mon Jan 09, 2023 6:29 am Another field of stars for you, Ann.
Maybe these blueberries are tiny rocks on Mars?
...
Then again, maybe the blueberries are galaxies?
or maybe they are star sapphires?
star-sapphire.jpg
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Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

De58te
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Out of curiosity just how fast is this comet speeding? According to Ann's C/2022 E3 (ZTF) link showing the comet's path it states that the comet will make its closest approach to Earth on February 1st, and then according to the diagram the comet will just whiz past Mars between February 11 and 12. That's just 10 days for it to travel between Earth and Mars! With NASA they say their rockets have to take between 8 to 9 months to make the same journey!

Chris Peterson
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

De58te wrote: Mon Jan 09, 2023 6:56 pm Out of curiosity just how fast is this comet speeding? According to Ann's C/2022 E3 (ZTF) link showing the comet's path it states that the comet will make its closest approach to Earth on February 1st, and then according to the diagram the comet will just whiz past Mars between February 11 and 12. That's just 10 days for it to travel between Earth and Mars! With NASA they say their rockets have to take between 8 to 9 months to make the same journey!
I'm not sure where you're getting that. The comet's inclination makes its orbit almost perpendicular to the plane of the Solar System. It will not go anywhere near Mars, nor cross Mars's orbit.
Chris

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Ann
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

MarkBour wrote: Mon Jan 09, 2023 6:29 am Another field of stars for you, Ann.
Mark, I didn't realize these were star sapphires! How stupid of me!

Thanks for setting me straight, bystander!

Ann
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johnnydeep
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Ann wrote: Mon Jan 09, 2023 7:30 pm
MarkBour wrote: Mon Jan 09, 2023 6:29 am Another field of stars for you, Ann.
Mark, I didn't realize these were star sapphires! How stupid of me!

Thanks for setting me straight, bystander!

Ann
Me neither. I had no idea what MarkBour's pic of a bunch of blue rocks with star-like patterns on them actually were!

But, Ann, what was the problem with saying "the unusual green color" :
The unusual green color is likely due to presence of diatomic carbon, chiefly around the comet's head.
The unusual green color? How many color images of comet comas has the writer of the Wikipedia page seen?
Is it just that it's not unusual at all, but quite common?
--
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Ann
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

johnnydeep wrote: Mon Jan 09, 2023 9:53 pm
But, Ann, what was the problem with saying "the unusual green color" :
The unusual green color is likely due to presence of diatomic carbon, chiefly around the comet's head.
The unusual green color? How many color images of comet comas has the writer of the Wikipedia page seen?
Is it just that it's not unusual at all, but quite common?
The problem was, indeed, the fact that the green color of the comet coma was called unusual. Like you said, that color in comet comas is not unusual at all, but extremely common in comets that are sufficiently close to the Sun and have developed a sufficient coma.

Here are a few green comet comas for your enjoyment.

Ann
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johnnydeep
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Ann wrote: Tue Jan 10, 2023 4:23 am
johnnydeep wrote: Mon Jan 09, 2023 9:53 pm
But, Ann, what was the problem with saying "the unusual green color" :
The unusual green color is likely due to presence of diatomic carbon, chiefly around the comet's head.
The unusual green color? How many color images of comet comas has the writer of the Wikipedia page seen?
Is it just that it's not unusual at all, but quite common?
The problem was, indeed, the fact that the green color of the comet coma was called unusual. Like you said, that color in comet comas is not unusual at all, but extremely common in comets that are sufficiently close to the Sun and have developed a sufficient coma.

Here are a few green comet comas for your enjoyment.

Ann
Thanks. You get extra points for not mentioning comet NEOWISE, which has also had a prominent green coma at times, but it was never that spectacular. From https://skyandtelescope.org/online-gall ... 2020sep-6/ -

--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

Chris Peterson
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

johnnydeep wrote: Tue Jan 10, 2023 3:58 pm Thanks. You get extra points for not mentioning comet NEOWISE, which has also had a prominent green coma at times, but it was never that spectacular.
I disagree. It was as bright green as pretty much any comet that gets near the Sun. But any really bright comet will become bright enough in reflected sunlight to hide the much dimmer green emission. You see the green when it is farther from the Sun and hasn't yet produced a lot of dust.

http://www.cloudbait.com/c2020f3.php
Chris

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johnnydeep
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Chris Peterson wrote: Tue Jan 10, 2023 4:09 pm
johnnydeep wrote: Tue Jan 10, 2023 3:58 pm Thanks. You get extra points for not mentioning comet NEOWISE, which has also had a prominent green coma at times, but it was never that spectacular.
I disagree. It was as bright green as pretty much any comet that gets near the Sun. But any really bright comet will become bright enough in reflected sunlight to hide the much dimmer green emission. You see the green when it is farther from the Sun and hasn't yet produced a lot of dust.

http://www.cloudbait.com/c2020f3.php
Ok. In my googling, I didn't seem to find many pictures of its green coma, which led to my comment.
--
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MarkBour
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Having previously owned a pet rabbit, I think I recognize
what those "blueberries" are.

However, in spite of the various forms of
evidence, NASA has never agreed that there is such a
species as a Mars Hare.
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Mark Goldfain

MarkBour
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Ann wrote: Tue Jan 10, 2023 4:23 am
johnnydeep wrote: Mon Jan 09, 2023 9:53 pm
But, Ann, what was the problem with saying "the unusual green color" :
The unusual green color is likely due to presence of diatomic carbon, chiefly around the comet's head.
The unusual green color? How many color images of comet comas has the writer of the Wikipedia page seen?
Is it just that it's not unusual at all, but quite common?
The problem was, indeed, the fact that the green color of the comet coma was called unusual. Like you said, that color in comet comas is not unusual at all, but extremely common in comets that are sufficiently close to the Sun and have developed a sufficient coma.

Here are a few green comet comas for your enjoyment.

(... A nice gallery excerpted ... see original post)

Ann
Looks like someone got your memo, Ann (although you could have made the change yourself easily). The word "unusual" was removed from the color description in the article https://en.wikipedia.org/wiki/C/2022_E3_(ZTF).
Mark Goldfain

Ann
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

MarkBour wrote: Sat Jan 21, 2023 6:41 pm
Ann wrote: Tue Jan 10, 2023 4:23 am
johnnydeep wrote: Mon Jan 09, 2023 9:53 pm
But, Ann, what was the problem with saying "the unusual green color" :

Is it just that it's not unusual at all, but quite common?
The problem was, indeed, the fact that the green color of the comet coma was called unusual. Like you said, that color in comet comas is not unusual at all, but extremely common in comets that are sufficiently close to the Sun and have developed a sufficient coma.

Here are a few green comet comas for your enjoyment.

(... A nice gallery excerpted ... see original post)

Ann
Looks like someone got your memo, Ann (although you could have made the change yourself easily). The word "unusual" was removed from the color description in the article https://en.wikipedia.org/wiki/C/2022_E3_(ZTF).
Wow, thanks for that info, Mark!

Well, I got to say - sometimes I think I'm right, but I just put my foot in it (like in the recent thread about the Crab Nebula and my pitiful attempt to identify the pulsar inside it ) but sometimes, darn it, I'm right for real.

Like when I talk about the color of things astronomical! Even though Chris likes to disagree!

Ann
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johnnydeep
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

Ann wrote: Sat Jan 21, 2023 7:08 pm
MarkBour wrote: Sat Jan 21, 2023 6:41 pm
Ann wrote: Tue Jan 10, 2023 4:23 am

The problem was, indeed, the fact that the green color of the comet coma was called unusual. Like you said, that color in comet comas is not unusual at all, but extremely common in comets that are sufficiently close to the Sun and have developed a sufficient coma.

Here are a few green comet comas for your enjoyment.

(... A nice gallery excerpted ... see original post)

Ann
Looks like someone got your memo, Ann (although you could have made the change yourself easily). The word "unusual" was removed from the color description in the article https://en.wikipedia.org/wiki/C/2022_E3_(ZTF).
Wow, thanks for that info, Mark!

Well, I got to say - sometimes I think I'm right, but I just put my foot in it (like in the recent thread about the Crab Nebula and my pitiful attempt to identify the pulsar inside it ) but sometimes, darn it, I'm right for real.

Like when I talk about the color of things astronomical! Even though Chris likes to disagree!

Ann
The editor was "Kheider". See https://en.wikipedia.org/w/index.php?ti ... on=history -
16:27, 21 January 2023‎ Kheider talk contribs‎ 11,805 bytes +24‎ (from the Oort cloud) undo
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

Ann
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### Re: APOD: Tails of Comet ZTF (2023 Jan 09)

johnnydeep wrote: Sat Jan 21, 2023 7:31 pm
The editor was "Kheider". See https://en.wikipedia.org/w/index.php?ti ... on=history -
16:27, 21 January 2023‎ Kheider talk contribs‎ 11,805 bytes +24‎ (from the Oort cloud) undo
Thanks, Johnny!

Ann
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