Talk:67P/Churyumov–Gerasimenko

Density

102 +/-9 kg/m-3 ? wouldn't that be a density just 1/10th that of solid ice? Yes, I see that number in the referenced document [2], but it doesn't make sense to me. — Preceding unsigned comment added by 216.160.113.36 (talk) 00:00, 30 March 2014 (UTC)

It is also a function of the porosity of the object. It is common for a comet to have a density much less than water. -- Kheider (talk) 17:47, 20 June 2014 (UTC)

Mass

Currently, the mass is given as “3.14×10¹²±0.21×10¹² kg.” I think it would be more readable if it was given as “3.14±0.21×10¹² kg.” Is there any rule on how to format in this case?

Your suggestion makes complete sense. I've gone ahead and applied the change. — Huntster (t @ c) 10:13, 4 August 2014 (UTC)

Per this update, the mass is actually "1.0±0.1×10¹³ kg.” (The exact text is "Using 80 hours worth of tracking data between 6 August, since arriving at the comet, and up to 9 August, the RSI team made a first estimate of the comet’s mass as approximately 1x10^13 kg +/-10%, or about 10 trillion kilograms.") 8.25.3.50 (talk) 20:13, 21 August 2014 (UTC)

Great find, I've updated the article accordingly. — Huntster (t @ c) 01:17, 22 August 2014 (UTC)

Should we use an ESA image of the comet's surface?

Comet Churyumov–Gerasimenko is currently being explored by the European Space Agency's Rosetta space probe which has already taken numerous detailed photographs of the comet's surface and has revealed the incredibly bizarre and complex shape of its nucleus. It would of course be extremely informative to readers if we could illustrate the article with one of these photographs. Unfortunately, ESA images are released under a non-free license, which means that although we can use them on Wikipedia, we need a good justification for it.

User:Huntster has objected to including an ESA image because the article already has a free-licensed image of the comet. Hunster explains, "I interpret the non-free rules as meaning that when a freely licensed image of a subject is available, then regardless of the superiority of any non-free alternative, the free image must be used". I believe Hunster's interpretation is overly strict. As you can see the free image merely depicts the comet as a dot of light, whereas the ESA images show the details of its unique shape. I therefore propose that the ESA image must be used to illustrate the surface features of the comet which are invisible in the free image. This is not a matter of beautifying the article but of being informative about the subject since the shape of the comet's nucleus is so complex that it could not be conveyed adequately in words.

Hunster has proposed that I try to find out what the consensus is among users of the article, so my question to readers is: Do you think it is justifiable for us to use an ESA image of the comet's nucleus is in this article, or do you think we must use only the free image (in which the comet is a dot of light)? Thanks for your comments. Arsia Mons (talk) 16:09, 5 August 2014 (UTC)

• I feel it would constitute fair use here as the remarkable shape of the comet is difficult to describe in text, and no free image showing the shape of the comet will be available in the foreseeable future. Bericht 16:20, 5 August 2014 (UTC)
• I agree with a better image. Fair use would surely apply, in this instance? ESA's Image Copyright Notice states that they can be used for informational purposes, when properly credited. As long as one of these images are properly credited, once transferred to Commons Wikipedia, I don't see the problem. As this is the first close encounter with the comet, there is no other source for such a close-up image, right now. EP111 (talk) 17:44, 5 August 2014 (UTC)

No I'm afraid ESA images are not free enough for commons, this has been argued to death a number of times. ChiZeroOne (talk) 19:53, 5 August 2014 (UTC)

Would it be free enough to upload to Wikipedia, instead of Commons? I understand that Wikipedia can allow somewhat less restriction, under certain circumstances. WP:FREER could apply, if it was uploaded directly to Wikipedia. For example: a. Can this non-free content be replaced by a free version that has the same effect? No, because the surface of the object, and the outline, is not clearly visible in any free image. b. Could the subject be adequately conveyed by properly sourced text without using the non-free content at all? No. The object is non-uniform, and difficult to convey in a description by text, alone. EP111 (talk) 20:46, 5 August 2014 (UTC)

I hate to say it, but I disagree with your assessment of clause b, it's already being described in the media as a "rubber duck-shaped" which should serve as a quick lay description. Furthermore, creation of a simple free-use illustration would not be too onerous an undertaking, should more detail be required. -Oosh (talk) 06:59, 6 August 2014 (UTC)

Only early low resolution images were described as a rubber duckie. The high resolutions ones look nothing like a rubber duckie. -- Kheider (talk) 13:38, 6 August 2014 (UTC)

• It is a very arguable point, the use of non-free material is a last resort and it does have strict requirements. There is a free image of the comet and so using a non-free image is difficult to justify. The bar is quite high, it's not merely about what you would like to illustrate. ChiZeroOne (talk) 19:46, 5 August 2014 (UTC)

  I would like to see one at ~200-350px, but I agree it would probably get removed by a wiki cop/enforcer. -- Kheider (talk) 20:42, 5 August 2014 (UTC)

• If you look at the article describing the asteroid 21 Lutetia, you will see that an ESA image taken by the same spacecraft is used in the article, even though there are free images of 21 Lutetia which show the body as a speck of light (http://arxiv.org/abs/0912.4572). -- Bericht (talk • contribs) 09:11, 6 August 2014 (UTC)

Yes, and after a deletion discussion at WP:Files for deletion/2010 July 11#File:Lutetia closest approach (Rosetta).jpg, it was kept. Thincat (talk) 12:28, 6 August 2014 (UTC)

The Lutetia image is also somewhat larger (2,103×2,078px) than the one which is currently in use in the 67P article (300×217px), and may also be considered more presentable, as it isn't so closely cropped. The format for the Lutetia image can also be applied to the 67P image, as that size format has implicit allowance too. EP111 (talk) 12:46, 7 August 2014 (UTC)

Mass changes after heliocentric orbit shift in 1959

Do we have any papers published that we could cite to improve the article on how the much-closer-to-the-Sun perihelion in the eight 6.45-year orbits of the Sun that 67P has made since 1959, when it's orbit was dramatically changed?

The article currently says this:

Orbital history

Comets are regularly nudged from one orbit to another when they encounter Jupiter in close proximity. Before 1959, Churyumov–Gerasimenko's perihelion distance was about 2.7 AU (400,000,000 km). In February 1959, a close encounter with Jupiter<ref name="jpl-close" /> moved its perihelion inward to about 1.3 AU (190,000,000 km), where it remains today.<ref name="Kinoshita" />

It would seem that the closer solar approach would result in much higher mass outflow rates of water/ice from the cometary mass on each solar approach. N2e (talk) 16:23, 8 August 2014 (UTC)

That also would depend on how close to the Sun the comet was in the even more distant past. Comets can spend 10,000 years bouncing around the inner solar system. -- Kheider (talk) 16:40, 8 August 2014 (UTC)

Image used unlikely to meet Wikipedia fair use standard

The image now at the infobox is of such a high resolution that I cannot believe it meets Wikipedia's fair use standard. Furthermore the image page description appears to contain the now incorrect claim:

It is believed that low-resolution copies of this image:
   taken directly from the ESA Multimedia Gallery,"

...

qualify as fair use under United States copyright law.

-84user (talk) 14:09, 10 August 2014 (UTC)

I have reverted the image to the low res version as it does not need to be high-res to be used as a fair-use thumbnail to illustrate the comet nucleus. -- Kheider (talk) 15:58, 10 August 2014 (UTC)

Rosetta NAVCAM images now available under a Creative Commons licence

It's done ! All ESA Rosetta NAVCAM images are licensed under CC BY-SA 3.0 IGO. Thank you dear ESA ! :) => http://blogs.esa.int/rosetta/2014/11/04/rosetta-navcam-images-now-available-under-a-creative-commons-licence/ . Sincerely, --Neptunia For talk with Neptunia 21:13, 4 November 2014 (UTC)

"How fast could 67P go around the earth?" is a trick question

   An otherwise reliable source asks "How fast is the comet traveling?", and answers "The comet is traveling 83,885 miles-per-hour.", which is pretty reasonable. But it continues "At that speed, it would take only 18 minutes to circle the Earth." which invites horribly misleading imagery: the arithmetic is right, for an object in uniform circular motion around the earth's equator, but that image gets the physics almost as wrong as when the Millennium Falcon made the Kessel Run in less than twelve parsecs: anything moving at such a speed parallel to the earth's surface can't stay close to the surface without expenditure of great amounts of energy in forcing it to stay close to the surface instead of tearing away along a path that is much closer to being a straight line than a circle. (We'd do better with "its speed at the time of the Philae mission was about 50 times that of an F-22 Raptor at full throttle.")
   It also describes "the comet, which itself is circling the sun at 83,885 miles per hour", altho what it is doing is not circling, but orbiting along an elliptical orbit that is so slim that it's hard to distinguish it from a parabolic one. (And its speed varies drastically with distance from the sun.)
   Our editors should watch out for confusing statements, in sources that may be unreliable re this topic -- even if we are used to trusting them as reliable on most topics.
--Jerzy•t 10:03, 12 November 2014 (UTC)

I don't see how these things would be useful for this article anyway. --JorisvS (talk) 10:23, 12 November 2014 (UTC)

Gravity assist?

This article says:

Comets are regularly nudged from one orbit to another when they encounter Jupiter in close proximity using gravity assist.

But gravity assist says:

In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement (e.g. orbit around the Sun) and gravity of a planet or other astronomical object to alter the path and speed of a spacecraft...

It seems that one is talking about natural phenomena and the other is talking about an engineered process. Isn't this a problem? — Brianhe (talk) 17:19, 13 November 2014 (UTC)

Yes, I've been thinking about that passage. The only difference between them I have been able to find, is that gravity assists in their normal meaning are a planned trajectories, whereas natural objects' orbit of course aren't. But that's not really much of a difference. Then again "using gravity assist" does not really add any information there, so can safely be removed (the original sentence did not include it). --JorisvS (talk) 17:53, 13 November 2014 (UTC)

Original name - Russian or Ukrainian

Now, that's what I call international effort - one ethnic Ukrainian citizen of USSR discovers a comet on the plates developed using equipment that formed part of an observatory based in Kazakhstan SSR by second ethnic Ukrainian citizen of USSR, who currently is a citizen of Tajikistan! Hence - comet name is given in all 4 relevant languages with said names given in order of relevance and priority. Given the time, place and circumstances of comet's discovery what should be the appropriate language reference for the comet's original name - Russian or Ukrainian? Since the the comet received its original designation within the framework of then current Soviet and International astronomical attribution practice, I believe Russian should serve as the language of the original name. And, if this persists to be perceived an issue I would rather have the entire reference to the language of the comet's name taken down than to see an historically incorrect reference be kept. Soviet citizens discovered the comet, soviet authorities named the comet - Russian was the official language of the the USSR and of the official Soviet naming body at the time - therefore the name of the comet as it was assigned then was indeed specified in Russian. — Preceding unsigned comment added by 184.144.210.224 (talk • contribs) 11:35, 14 November 2014‎

Because it is identical in both languages, can't we simply list it as being both Ukrainian and Russian (and the name of course only once)? --JorisvS (talk) 13:32, 15 November 2014 (UTC)

I specifically mean saying something like "Russian and Ukrainian: Комета Чурюмова — Герасименко", not "Russian: Комета Чурюмова — Герасименко, Ukrainian: Комета Чурюмова — Герасименко", because the latter is needlessly long and does not really show that its name is the same in both languages. --JorisvS (talk) 13:39, 17 November 2014 (UTC)

Actually what is not identical is the spelling of the first name. If we follow the Ukrainian it should be Svitlana rather than Svetlana. I left a comment at Talk:Svetlana Gerasimenko. Tkuvho (talk) 14:42, 17 November 2014 (UTC)

Okay, but that has no bearing on the comet's name. --JorisvS (talk) 16:46, 17 November 2014 (UTC)

 Done - FWIW - added => "(Russian and Ukrainian: Комета Чурюмова — Герасименко," - hope this helps in some way - in any case - Enjoy! :) Drbogdan (talk) 17:03, 17 November 2014 (UTC)

French

Apparently the French observed the asteroid in august of the same year but it was named after Ch-G anyway. Should this be reported? Tkuvho (talk) 15:08, 18 November 2014 (UTC)

Observing the object and recognizing it as a newly found object (why exactly do you call it an "asteroid"), observing a comet and calculating its orbit in order to definitively establish it is as a newly observed comet - these separate casual observers who simply happen to glance upon the sky using whatever equipment they chance to have at the time from true discoverers. This does not need to be "reported" but simply added, so that an emphasis is given to the fact that celestial objects are very often "prediscovered" but are not recognized as anything new and therefore only those who have observed the object, understood its nature and computed its orbit are accepted as the discoverers. There is no contradiction - French astronomers ("by the way" number one - there are names and dates and references and links, right?) who merely "observed" ("by the way" number two - what exactly do your sources say this involved?) the object have no right to be naming said object. — Preceding unsigned comment added by MURODURUS (talk • contribs) 11:23, 18 November 2014‎

Duck, Regions

The shape is frequently and simplifying described as a rubber duck (Gummientchen), with smaller head, connecting neck and bigger body. Now, by different surface structures 19 regions are distinguished. See: Astronomie: Die wunderbare Welt des Kometen "Tschuri" (German: The wonderful world of the comet "Chury" ), ORF.at, 23 January 2015 --Helium4 (talk) 06:36, 24 January 2015 (UTC)

External Links

Added: www.scientificamerican.com/article/strange-comet-discoveries-revealed-by-rosetta-spacecraft — Preceding unsigned comment added by Jcardazzi (talk • contribs) 20:29, 30 January 2015 (UTC)

And removed as failing WP:EL. If it can be used as a citation, then integrate it into the article as such. However, I noticed nothing unique in that article that isn't already provided by other citations. — Huntster (t @ c) 21:22, 30 January 2015 (UTC)

-to the author: Is this article worth adding as an external link, for the sequence of photographs and explanations? http://www.nytimes.com/interactive/2015/03/20/science/space/rosetta-comet-photos.html Thank you, Jcardazzi (talk) 13:20, 21 March 2015 (UTC)jcardazzi

All those images are already available through ESA's Flickr page, which is linked to in the External Links section. — Huntster (t @ c) 17:43, 21 March 2015 (UTC)

There is quite a bit more information in http://phys.org/news/2015-07-imhotep.html. Graeme Bartlett (talk) 00:43, 23 July 2015 (UTC)

"Life on comet" paragraph

There's a paragraph on the claims made at a conference and through a press release that the comet might have life on it. As far as I know, these claims haven't been formally published and are not viewed as credible outside of the lay press. While they've made some column inches at the moment, I doubt they're the sort of thing that's going to be worth keeping around in a few weeks, or a month. See, for example, the "earth shaking" news around the Curiosity mission that turned out to be a reporting error. I open the issue for discussion.131.111.185.44 (talk) 08:24, 10 July 2015 (UTC)

I vote for leaving this short paragraph in the article, at least for the nonce - because discerning readers will see the lay press stories and then come to WP, where they will learn that it is unsupported speculation. Putting a scientific perspective on sensational press reports is one of the services that WP should provide, IMHO, because that sort of clarification is not readily available elsewhere to the average reader. DoctorJoeE ^{review transgressions}/_{talk to me!} 13:13, 10 July 2015 (UTC)

Claims by Wickramasinghe generally lack any scientific evidence, but I guess they make for exciting journalism. It is not like someone has sampled diatoms from the surface of the comet. -- Kheider (talk) 17:09, 10 July 2015 (UTC)

True enough; but since tabloid publications and pseudoscience blogs do not point out that the life-on-the-comet speculation is unsupported, WP should - and that's why I vote for leaving it in the article. DoctorJoeE ^{review transgressions}/_{talk to me!} 22:21, 11 July 2015 (UTC)

Shrinking?

Is it known by how much the comet shrinks (radius or mass) each time it passes by the sun? AxelBoldt (talk) 17:27, 29 October 2015 (UTC)

Electricity

Shouldn't this include alternate attempts at explaining the bizarre phenomena? I get that there's been a concerted effort to shun any electrical theories, but there is a lot of credence to be given to this hypothesis.

Look at these formations in calcium-rich soils in the United States. notice the similar formations: http://www.science-frontiers.com/sf129/sf129p09.htm

(I attempted to add a you tube video about Billy Yelverton's plasma-in-dust laboratory experiments but Wikipedia blocked it, not cool guys, not cool.)

These among other sources could easily be investigated and used to build an alternate explanation for the shape and phenomena involving this enigmatic comet. As ESA have admitted, there are still many inherent mysteries, so why not be truly scientific about it and investigate all possibilities?

Or are you guys more interested in closing minds than opening them? — Preceding unsigned comment added by Kreative78 (talk • contribs) 18:03, 18 January 2016 (UTC)

you need a RS to add that "info" 104.169.37.99 (talk) 20:33, 12 November 2022 (UTC)

Removed reference

The following reference was removed as no longer used. I thought i'd pop it here in case it's useful in the future.

LenTheWhiteCat 13:18, 13 April 2016 (UTC)

References

File:Comet 67P on 19 September 2014 NavCam mosaic.jpg to appear as POTD soon

Hello! This is a note to let the editors of this article know that File:Comet 67P on 19 September 2014 NavCam mosaic.jpg will be appearing as picture of the day on November 22, 2016. You can view and edit the POTD blurb at Template:POTD/2016-11-22. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the Main Page. — Chris Woodrich (talk) 08:16, 7 November 2016 (UTC)

Picture of the day

A black-and-white photographic mosaic depicting the comet 67P/Churyumov–Gerasimenko, as photographed by the probe Rosetta. This Jupiter-family comet, which was originally from the Kuiper belt, is about 4.3 km (2.7 mi) across, has a current orbital period of 6.45 years, a rotation period of approximately 12.4 hours, and a maximum velocity of 135,000 km/h (38 km/s; 84,000 mph). It was first observed on photographic plates in 1969 by Soviet astronomers Klim Churyumov and Svetlana Gerasimenko, after whom it is named.Photograph: ESA/Rosetta/NAVCAM

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coupling two comets to form this comet

for the first time:I noticed

I want to say that the comet 67P/ Churyumov–Gerasimenko which is a Jupiter-family comet ,has been formed by coupling two comets .

It is displayed on the picture and same as which NASA discovered recently . European spacecraft Rosetta studied it and send Phile to land on the comet.

it will be wonderful that we study matching and approach process of two body in weak gravity field .

I see some considerable absorption signs between them ..--Akbarmohammadzade (talk) 11:12, 17 January 2019 (UTC)

Proposal to re-structure article

The current structure of this article does not do justice to the wealth of scientific returns of the Rosetta mission. I propose to move chapter "5. Rosetta mission" upwards and insert it between chapters 1 and 2, then remove the subsection "science". The contents of "science" need to be updated and expanded, merging them with the chapters that currently treat shape, surface, and other properties of 67P. Is anyone opposed to this proposal, or has a different idea? --Geowissenschaftlerin (talk) 13:58, 14 August 2019 (UTC)

I agree in that the whole article should deal with the science of the asteroid, not just one section. I say: go for it. And I suggest you perform gradual changes with appropriate edit summaries so it can be followed and reviewed. (Blending the science section would be expected, as supposed as deleting it.) Cheers, Rowan Forest (talk) 14:25, 14 August 2019 (UTC)

Alright, I'll work on it when I get some time. Thank you for the answer! — Preceding unsigned comment added by Geowissenschaftlerin (talk • contribs) 09:24, 15 August 2019 (UTC)

Since we are concentrating less on the spacecraft operations by Rosetta and more on the science it produced, I propose to delete the spacecraft Landing section and other similar mission operations. That is dealt with at the Rosetta (and its lander) articles. Rowan Forest (talk) 16:26, 16 August 2019 (UTC)

"Churymoon"

ESA announced a couple weeks ago that a small piece of debris was discovered orbiting the comet for about 2 days in Oct 2015. Is this significant enough to mention in the article? --Lasunncty (talk) 00:08, 28 August 2019 (UTC)

Small pieces of debris (~4 meters in size) will briefly orbit active comets on a regular basis. -- Kheider (talk) 00:33, 28 August 2019 (UTC)

Composition!

How can the composition of the comet not be mentioned at all in this article?! Not a word on what it's made of, surface, gas and dust...

Could someone add please? After all, that's pretty much the whole reason we went there. Dan100 (Talk) 09:53, 18 June 2020 (UTC)

True Color Image?

I saw another version of "True Color" image of this comet which it looks mostly grey here (http://www.sci-news.com/space/science-true-colors-comet-67p-churyumov-gerasimenko-02342.html), but the true color image that currently use on this page looks reddish, should we make a confirmation of which is the "real" color so we can provide the most accurate image for readers? — Preceding unsigned comment added by Jonathan Chone (talk • contribs) 10:01, 11 March 2022 (UTC)

It has a moon

A inch wide chuck of debris was captured in a photo by the rosseta spacecraft nicknamed chury-moon 198.38.49.103 (talk) 19:55, 1 October 2022 (UTC)

Earthsky 2214

Earthsky incorrectly suggests an Earth approach in 2214. 67P comes to perihelion on 2211-Feb-12 (1.1 AU from the Sun and 1.3 AU from Earth). It comes to aphelion on 2214-Feb-04 at 5.5 AU from the Sun and 5.9 AU from Earth. -- Kheider (talk) 15:24, 17 July 2023 (UTC)

The orbit has been updated a few times since that article was written, so perhaps it was accurate at the time of writing. But thanks for double checking! --Lasunncty (talk) 20:17, 17 July 2023 (UTC)

Jupiter 1840

According to Kinoshita, the close approach to Jupiter in 1840 actually moved perihelion outwards from 2.44 AU (18380107) to 2.79 AU (18461103), So I have removed the dated (incorrect) paragraph. Using a slightly different dataset (1969-2004), JPL Horizons is in good agreement that perihelion in 1821 was around 2.42 AU. -- Kheider (talk) 04:51, 18 July 2023 (UTC)