Talk:C/2022 E3 (ZTF)

Fly-by unexplained?

The current article fails to discuss why this comet is not being visited, considering its significe to science and how it comes around so rarely (like Neanderthals saw it first and we are the last to see it). Plus the comet was discovered by deep space scan with a full year of forewarn and using the rapid turn-around allowed by SpaceX (Heavy) Falcon reusable rocket tech, satellites can now be launched on a few weeks notice. 94.21.154.101 (talk) 12:11, 14 January 2023 (UTC)

It is a common ~1 km long-period comet that might reach naked eye status from dark locations. Small/diffuse comets really need to reach about magnitude 4.5 to stick out to casual observation. -- Kheider (talk) 13:26, 14 January 2023 (UTC)

Notice that the ecliptic inclination is 109 degrees. Hitting it hard would be somewhat difficult, and meeting it without violence would be hugely difficult. Jim.henderson (talk) 08:56, 16 January 2023 (UTC)

As of 31 Jan 2023 2022 E3 still has not established MY apparent magnitude 4.5 requirement for a public fuzzy naked eye object given the low surface brightness. Given a bright Moon is high over head making strong shadows during the evening, I expect a lot of people will not find it naked eye or point their 10x42 binoculars in the wrong place? I do not know if a bright moon overhead is as bad as artificial light pollution for washing out the comet. -- Kheider (talk) 23:05, 29 January 2023 (UTC)

photo

It looks like the red, green, and blue aren't aligned in the photograph. Bubba73 ^{You talkin' to me?} 16:33, 16 January 2023 (UTC)

It looks like the telescope was tracking the comet while using different colored filters via a filter wheel. Once the images are stacked on the comet, the untracked stars create trails that are the color of the filter. The gap in the trails is created during the changing of filters. -- Kheider (talk) 18:02, 16 January 2023 (UTC)

Oh, yes, that must be the reason! Bubba73 ^{You talkin' to me?} 23:18, 16 January 2023 (UTC)

Sizeable matters.

The article doesn't say much about the size (mass) of this comet, even though that's some important info. Is it a few hundred meters or a few kilometers across (since it was initially considered an asteroid, the kind that destroyed Tunguska). How many megatons would it equal if hitting anything? 188.143.6.126 (talk) 08:12, 24 January 2023 (UTC)

Size? Largely unknown unless a large observatory studies it, which would probably happen at closest approach for better resolving power. But I would say given how DIM it is at 60 million km from Earth, that it is a little less than 1km in diameter. As for mass? All you could do is assume a size and density of say 1 g/cm³, but such an assumption for mass would be so inaccurate as to be meaningless. -- Kheider (talk) 11:14, 24 January 2023 (UTC)

Inbound vs. Outbound Orbit

The article implies that there is a difference between the inbound and outbound orbit of the comet, providing two different eccentricities. However, the reference for the inbound eccentricity is actually the same as for the outbound eccentricity. Does anyone have a correct reference for the inbound orbital elements? Is it known at one point its orbit changed? AstroMark (talk) 14:50, 30 January 2023 (UTC)

The source has two eccentricities, one for 1950 (EC= 9.991915796483135E-01), that it is the inbound, and one for 2050 (EC= 9.999911858012263E-01), that it is the outbound. The changes happen in the inner solar system because of the gravity perturbations of the planets. --C messier (talk) 17:48, 30 January 2023 (UTC)

Thanks for the clarification. The source is certainly not the clearest to understand. I was misled by the EC=1.000271629058961 at the top of the page. Actually there are some things I still don't understand. Why have the epochs of 1950 and 2050 been chosen? What's the purpose of also including an eccentricity for a heliocentric orbit and why was an epoch of 2495 chosen for that? AstroMark (talk) 21:47, 30 January 2023 (UTC)

1950 is before the comet was perturbed be the planets. 2050 is after the comet is perturbed by the planets. A heliocentric eccentricity in 2495 was picked as an extreme to show how this comet is borderline between ejection (heliocentric 2495) and remaining bound the Sun barycentric (but with an unrealistic aphelion of 270,000 AU (4.3 ly). If you look here you can see how the heliocentric solution varies between bound and unbound even centuries after leaving the planetary region of the Solar System. C/2013 US10, on a long-term ejection trajectory, does NOT flip back and forth between bound and unbound hundreds of years from now. -- Kheider (talk) 07:09, 31 January 2023 (UTC)

The long-term outbound trajectory near the outer Oort cloud is so sensitive/borderline for this comet, do not be surprised if minor outgassing events change the long-term solution for this comet. The uncertainty in the position of the comet has grown from ±300 km to ±500 km due to post-perihelion outgassing. Since we do not know the precise mass of the Solar System (Keplerian GM : 1.3289051882026906E+11 km^3/s^2), I am not completely confident this borderline case makes it out of the Solar System. -- Kheider (talk) 17:30, 1 February 2023 (UTC)

I still have some concerns with this.

• The use of 1950 and 2050 seems completely arbitrary. I see that these dates have also been used in many other comet articles for the same purpose. This is obviously going to become a more problematic choice the closer we get to 2050. Why not choose dates that are ± a number of years from perihelion? Or at least choose dates that are a few hundred years into the past/future. For the heliocentric calculation, a date of 2495 has been chosen. But not for the barycentric case. Why the inconsistency?
• I still don't really see the point of including the heliocentric case, particularly now that both are giving eccentricities above 1.
• Personally I'm concerned that using JPL Horizons in this way counts as original research as these are not routine calculations. As far as I can tell, the code to run the calculations is not even published anywhere. I know there was a whole debate about that over at Talk:ʻOumuamua/Archive_2#Is_the_Inbound_Velocity_table_original_research? and it does seem like the majority are clearly of the opposite view so I don't intend to open up that debate again, I just felt the need to mention it. AstroMark (talk) 19:19, 22 February 2023 (UTC)

For highly eccentric Oort Cloud type comets, you NEED to use dates when the comet is OUTSIDE of the planetary region of the Solar System. 1950 and 2050 will currently give you pretty much the same result as 1800 and 2200 as they will both have the comet outside of Neptune's orbit. But I agree, in the near future using 2100 or 2200 will be better for newer Oort cloud comets. JPL Horizons is really nothing more than a database lookup. Most other sources will simply be too simple and wrong as they will be defined at an epoch (time) when the comet is near the Sun. That is great for loading into Stellarium and pointing a telescope, but not useful for knowing the inbound vs outbound orbital periods. -- Kheider (talk) 20:20, 22 February 2023 (UTC)

Why do you refer to JPL Horizons as a database lookup? Is it not running an n-body simulation every time you query it? AstroMark (talk) 22:31, 2 March 2023 (UTC)

JPL Horizons normally re-compiles the database (for objects with new observations) once-a-day around 5am Pacific time. You are accessing a stored database. -- Kheider (talk) 02:09, 3 March 2023 (UTC)

Where are you getting this information? Looking through the documentation I found the following:

Because of the large number of small bodies, their orbit solutions are stored compactly in a database as osculating orbital elements at one epoch, the geometrically meaningful form of position and velocity at a single instant. For those few cases requiring a non-standard dynamical model, information on that force model is also stored. When a full trajectory is needed, those initial conditions are then propagated to other times by numerically integrating those initial conditions using the appropriate dynamical model of forces acting on the object.

In other words, if you just use the database lookup, you will only find the orbital elements at a specific epoch (e.g. [1]). If you want orbital elements at another epoch, those need to be calculated.

That said, I agree that there is not an obvious alternative and it would be shame not to have this information - indeed that's why I first came to this page after all - so I can't say that I have an alternative solution other than setting up a website dedicated to providing this information, just so that it can be cited by Wikipedia, which is obviously not ideal. AstroMark (talk) 21:27, 3 March 2023 (UTC)

mag X star vs mag X comet

Kheider this info, apart from unreferenced, is it really that important to be in the lead? This is generic diffuse object info that is absent from most if not all diffuse object articles. C messier (talk) 14:08, 31 January 2023 (UTC)

"A magnitude 5 star is easier to see than a magnitude 5 comet because the comet has a low surface brightness and we see the same total amount of light from the comet as we would from a star of the same magnitude." Yes, I think it should be listed in the article somewhere because it is very useful information to know. This is the very reason some people can see mag 8 stars, but only mag 6.9 galaxies. -- Kheider (talk) 16:28, 31 January 2023 (UTC)

Most people don't really know how bright a 5th magnitude star is, so it doesn't really help to mention it will be more difficult to see the comet than that stars. The "dimly visible with the naked eye as a small diffuse smudge under a dark enough sky, but most viewers will need an instrument such as binoculars." should suffice (and I'm still not sure about the dimly). C messier (talk) 17:57, 31 January 2023 (UTC)

I have restored some mention of surface brightness to the article because to exclude it entirely is to mislead the readers. -- Kheider (talk) 00:21, 1 February 2023 (UTC)

Thanks all

I learned a lot from this article with basically zero background knowledge. Thanks to everyone who contributed. jengod (talk) 18:11, 1 February 2023 (UTC)

≈50,000 yr (inbound)[2] Ejection or many millions of years (outbound)

That is confusing statement. I mean what is the correction. Two possibilities. - Ejection million years - Many million years What is correct? 2404:8000:1027:85F6:869:A8D8:24B0:CEC1 (talk) 22:04, 1 February 2023 (UTC)

Basically both/unknown. The outbound trajectory is very close to parabolic even defined at an epoch in the year 2500. See Talk:C/2022_E3_(ZTF)#Inbound_vs._Outbound_Orbit. -- Kheider (talk) 22:14, 1 February 2023 (UTC)

is the sentence "ejection millions of years" correct? Because the word "or" is flanked between words "ejection" and "many". 2404:8000:1027:85F6:869:A8D8:24B0:CEC1 (talk) 22:29, 1 February 2023 (UTC)

"Ejection OR many millions of years (outbound)" is correct. All ejections are millions if not billions of years. Outer Oort cloud comets take millions of years to orbit the Sun. -- Kheider (talk) 22:41, 1 February 2023 (UTC)

It is also confusing to comprehend that grammar. I mean Either the two possibilities of "or" word with the "Ejection of years" and "many millions of year" are right, isn't it? 2404:8000:1027:85F6:869:A8D8:24B0:CEC1 (talk) 04:28, 2 February 2023 (UTC)

I think you are looking for precision where there is none. Any comet with a multi-thousand year orbit (much less more) is just a best fit to a curve and should be defined when it is outside of the planetary region of the Solar System, ie decades before and decades after perihelion. This comet may or may not orbit the Sun million of years from now as the eccentricity hundreds of years from now flips back and forth between above and below 1. -- Kheider (talk) 07:38, 2 February 2023 (UTC)

I mean i want to talk the grammar not the explanation! 2404:8000:1027:85F6:5553:1FEE:FFB2:935E (talk) 10:21, 2 February 2023 (UTC)

There is not a lot of room to get too wordy in the infobox. That is the reason we have a section called Outbound trajectory. -- Kheider (talk) 10:41, 2 February 2023 (UTC)

Ejection or many millions of years (outbound) because of the word "or" flanked between words "ejection" and "many" then there are two possibilities: - ejection millions of years and - many millions of years. Correct me if i am wrong. Because i barely comprhend the conjunction "or". 2404:8000:1027:85F6:8C19:7D14:3555:1670 (talk) 18:20, 2 February 2023 (UTC)

I agree with you that it's a little confusingly written here. I think what you're missing here is that the 'many millions of years' doesn't refer to the timescale for ejection, but rather the orbital period in the case that the comet is not ejected. Would it be more comprehensible if it was 'Many millions of years or unbound'? AstroMark (talk) 16:13, 21 February 2023 (UTC)

The pre-perihelion solution had the comet reaching 200AU from the Sun in the year 2236, due to outgassing, the new solution has the comet reaching 200AU from the Sun (4 years earlier) in 2232. It *should* be leaving the Solar System. -- Kheider (talk) 22:24, 21 February 2023 (UTC)

Infobox broken

Is there a reason Template:Infobox comet is not displaying the dimensions parameter? -- Kheider (talk) 14:27, 2 February 2023 (UTC)

Nucleus size reference

Andrew Davidson, the source (usatoday) points as its source PurnEAUniversity.Org where it is using weasel words (experts have estimated). Who are these experts? C messier (talk) 14:40, 2 February 2023 (UTC)

• USA Today wasn't an ideal source as they converted the estimate to feet. I have located a better source which attributes the estimate to a specific expert – Nicolas Biver – and have cited that instead. Andrew🐉(talk) 16:46, 2 February 2023 (UTC)

  This is much better. C messier (talk) 18:29, 2 February 2023 (UTC)

  I got this page when playing Universe Sandbox. 108.241.118.143 (talk) 20:59, 22 May 2023 (UTC)

Color

The second sentence mentions that the diatomic carbon "triplet state radiates at 518 nm (nanometers)" ... but the sixth sentence refers to a "wavelength range between 5000 and 7000 Å" — many readers may be unable to relate nm and Å. Wouldn't it be better to stick with one or the other? Prisoner of Zenda (talk) 12:05, 21 February 2023 (UTC)