Talk:ʻOumuamua/Archive 1

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Sentence in lede

"The high eccentricity both inbound and outbound indicates that it is not gravitationally bound to the Solar System and is likely an interstellar object." - shouldn't the comet be on a single conic section orbit (in this case, a hyperbola) in which case there is only one eccentricity, and "both inbound and outbound" is unnecessary? Further, since eccentricity > 1, it is by definition a hyperbolic orbit -> it's already given that the comet is not gravitationally bound to the Solar System. Banedon (talk) 21:24, 26 October 2017 (UTC)

The eccentricity will always be somewhat different inbound and outbound for any object as a result of planetary perturbations. Many comets bound to the Sun will briefly appear slightly hyperbolic either inbound or outbound. So it is useful to state that this object is strongly eccentric both inbound and outbound. This is what makes this object special. The barycentric eccentricity of 17U1 goes from 1.189 (epoch 1900) inbound to 1.193 (epoch 2100) outbound. -- Kheider (talk) 00:09, 27 October 2017 (UTC)

Wrong units?

I believe A/2017 U1 is moving at 44 km/sec which is about 27 miles /sec and not as written in the article. see here for example Golan's mom (talk) 12:32, 29 October 2017 (UTC)

17U1 is moving at numerous speeds depending on when and what you are comparing it to. It was discovered on Oct 19 when it was moving at 46 km/s with respect to the Sun (60 km/s wrt Earth). It was moving 26 km/s wrt the Sun when it was inbound 200 AU from the Sun. It peaked at 87.5 km/s wrt the Sun (68.8 km/s wrt Earth) when passing perihelion on 2017-Sep-09 11:19 UT. As of Oct 29, it is moving 43.6 km/s wrt the Sun. It will continue to slowdown until it reaches an interstellar cruising speed of 26 km/s. Put simply all objects move faster the closer they are to the Sun. -- Kheider (talk) 13:55, 29 October 2017 (UTC)

Infobox : Perihelion date

I am not familiar with the use of infoboxes. Why is the type 'infobox planet' and not 'comet' used here ? It seems to lack an important information, the perihelion date. This important parameter is only given at present in the text itself. Apparently when using an infobox 'comet', there is a keyword 'last_p' for this information. For A/2017 U1 according to the Minor planet circular quoted in the article, it is : T 2017 Sept. 9.41719 TT , to be rounded to Sept. 9, 2017 I guess to be homogeneous with other wiki pages, cf e.g. Comet_Hale–Bopp . Of course for an hyperbolic orbit 'last' perihelion is a bit strange (as it is the only one) - but that is not incorrect. Tenfeet33 (talk) 14:40, 6 November 2017 (UTC)

Since it is technically classified as an "asteroid" ("A/" as it has shown no cometary activity), we are using Template:Infobox planet. Most known minor planets are confined to the asteroid belt and come to perihelion every 5 years or so. So for minor planets with less than a ~10 year orbital period, the perihelion date is less significant than the opposition date. But I suppose an admin could add it. Perihelion is important for comets because they generally have very eccentric orbits and perihelion is generally when they out-gas the most. -- Kheider (talk) 20:12, 6 November 2017 (UTC)

"1I" ; "A/" ; "C/"

The article should explain the notation. "A/" isn't normal, and "1I" is totally new. "C/" should be explained as cometary notation. "A/" should be explained for comets that turned into asteroids (and not asteroidal notation). "1I" is new, not part of the "#C/" comets or "#P/" comets, so should definitely be explained, since it is a new class of classifications. I assume "I" means interstellar comet, since it looks like cometary notation (ie. "1P/Halley" for the first periodic comet whose periodicity was discovered). -- 70.51.45.76 (talk) 05:49, 7 November 2017 (UTC)

I also believe "A/" has never been used before. A handful of asteroids have been later classified as comets when cometary active is detected. But an "assumed"(?) comet has never been relisted as an asteroid as the MPC generally requires a secondary source to confirm the cometary nature of a newly discovered object. But as I follow asteroids more than comets I might be missing another example of the "A/" notation. "I/" is certainly meant to represent interstellar. -- Kheider (talk) 13:49, 7 November 2017 (UTC)

Light curve

What is the source of the light curve? Agmartin (talk) 16:46, 7 November 2017 (UTC)

Some recent papers

The rotation period and shape of the hyperbolic asteroid A/2017 U1 from its lightcurve

Implications for planetary system formation from interstellar object A/2017 U1

On the Consequences of the Detection of an Interstellar Asteroid

Agmartin (talk) 17:15, 7 November 2017 (UTC)

Correct name is 1I/ʻOumuamua (with ʻOkina), not 1I/'Oumuamua

The cCorrect name is 1I/ʻOumuamua (with ʻOkina), not 1I/'Oumuamua. I asked the Minor Planet Center by e-mail and got a quick answer from Gareth Williams referring to the reference “MPEC 2017-V17: NEW DESIGNATION SCHEME FOR INTERSTELLAR OBJECTS”:

• “The MPECs are an ASCII-only publication and Unicode characters cannot be used. The character in the name is an ʻokina and where a publication cannot represent the character exactly, a near equivalent should be substituted, according to the standards of the publication. This is similar to ASCII representation of cedillas, accents, haceks, etc.”

Thus, the article should in fact be moved to 1I/ʻOumuamua. I tried this, but apparently the destination name is currently blocked. Thus, I propose to perform this move by someone who has sufficient access permissions. -- Karl432 (talk) 22:39, 7 November 2017 (UTC)

We cannot base content on a personal email. It is not verifiable. Since the MPEC gives the official name and it is only ASCII we will have to stick with ASCII until they issue a bulletin with an explanation of the character that should be used. However I have created a redirect. We will see if anyone ever uses that https://tools.wmflabs.org/pageviews/?project=en.wikipedia.org&platform=all-access&agent=user&range=latest-20&pages=1I/%CA%BBOumuamua. Graeme Bartlett (talk) 23:46, 7 November 2017 (UTC)

Actually the supplied bulletin does have the "ʻOkina" character in it. So it is not exclusively ASCII. So I have moved the page to match the name as given in MPEC 2017-V17. Graeme Bartlett (talk) 00:38, 8 November 2017 (UTC)

a couple of sources if someone want add a mention of ʻokina to the article.

Michele Bannister‏ @astrokiwi Replying to @astrokiwi @MinorPlanetCtr Hello, ʻOumuamua! note:' is an apostrophe.ʻ is an ʻokina: a consonant. #A2017U1 https://twitter.com/astrokiwi/status/927686950957481984

Hawaiian words are pronounced just as they are spelled with every letter pronounced, but in this case the name has an ʻokina in front, which is like a glottal stop (I saw one description that it’s like the stop when you say, “uh-oh”). So this is pronounced Oh-oo-moo-ah-moo-ah, with the glottal stop in front http://www.syfy.com/syfywire/an-interstellar-rock-gets-a-name

I wouldn't quote Phil Plait's pronunciation without getting verification from someone that speaks the language.

This, for example, appears to indicate Phils is wrong, note the before and after.

Bob Collom‏ @call_him_bob 22h22 hours ago Replying to @astrokiwi @MinorPlanetCtr Pronunciation guide?

Adrien Coffinet‏ @AdrienCoffinet 19h19 hours ago It corresponds to a glottal stop. Practically, you can consider it as no "liaison" between the sounds before and after the 'okina.

Adrien Coffinet‏ @AdrienCoffinet 19h19 hours ago More or less what happens between the two vowels in “uh-oh” https://twitter.com/AdrienCoffinet/status/928013554543980545 Agmartin (talk) 16:45, 8 November 2017 (UTC)

Xenoästeroid

Andy Rivkin has started referring to it as a xenoästeroid https://twitter.com/asrivkin/status/923719587920797696 Agmartin (talk) 17:24, 27 October 2017 (UTC)

I probably prefer rogue asteroid or even manx comet. -- Kheider (talk) 19:43, 27 October 2017 (UTC)

Until and unless this coinage is picked up by many others, it will remain simply his. Kortoso (talk) 19:20, 20 November 2017 (UTC)

I like the umlaut, it makes it more sexy. Hell, it has an umlaut and an X. Ravish me now. AllGloryToTheHypnotoad (talk) 14:09, 21 November 2017 (UTC)

Not an umlaut, a diaeresis. 162.89.0.47 (talk) Eric —Preceding undated comment added 20:35, 22 November 2017 (UTC)

Flight path

Strange there is nothing about the unexpected flight path here. Is Wikipedia biased? -- 88.112.75.34

There is not much to say as the origin of the object is unknown. Vega was not in the same part of the sky 300000 years ago. It is near the solar apex which is to be expected as more bugs hit a front windshield than a back windshield. -- Kheider (talk) 23:33, 29 October 2017 (UTC)

Nothing about it being an interstellar spaceship too, I see. AllGloryToTheHypnotoad (talk) 14:10, 21 November 2017 (UTC)

not necessarily the inner solar system of wherever it hails from

Should "or have been in the inner region of that stellar system long enough for all ice to sublime" be "or have been in the inner region of a stellar system long enough for all ice to sublime". How would we know it sublimed in its source stellar system as opposed to one on the way? ϢereSpielChequers 23:33, 31 October 2017 (UTC)

Good point there. We cann't really know, but I'd reasonably doubt that it happened on the way given how short a time scale that would have to happen on. exoplanetaryscience (talk) 23:36, 31 October 2017 (UTC)

Temporary satellite captures (TSC) are fairly rare and short lived. There is no reason to think 17U1 has spent eons orbiting more than one star as a Short-period comet. Being a short-period comet for 100000+ years is how a comet can become an inactive "Extinct comet". -- Kheider (talk) 02:10, 1 November 2017 (UTC)

Thanks, I suppose that depends on how many stars it has approached and how closely as well of course as how big it actually is (the bigger the object the deeper some volatiles could once have been), presumably speeding up each time via slingshot effect? In any event I don't see how we know that the first solar system it left is the one where it lost all its volatiles. ϢereSpielChequers 10:34, 1 November 2017 (UTC)

And how do we know it had any volatiles at all in the beginning? 194.174.76.21 (talk) 13:30, 21 November 2017 (UTC) Marco Pagliero Berlin

Audio Pronunciation

Is it possible to get an audio pronunciation for this? This seems like such a minimum requirement, but I have never heard this pronounced. Parsing the phonetic pronunciation just isn't a reasonable expectation for the casual reader. — Preceding unsigned comment added by 146.165.229.159 (talk) 15:20, 14 November 2017 (UTC)

Try this — Preceding unsigned comment added by Tony873004 (talk • contribs) 16:36, 21 November 2017 (UTC) https://soundcloud.com/roy-gal-787702179/oumuamua-pronunciation

Latest axis ratio

Article in Nature has estimated 1I/ʻOumuamua axis ratio at 10:1. Out of curiosity I checked the dimensions of the Saturn V for a comparison, 110 m x 10.1 m. Agmartin (talk) 18:13, 20 November 2017 (UTC)

Possibly a coincidence. We may never know. Kortoso (talk) 19:22, 20 November 2017 (UTC)

"Looking at the asteroid light curve database, there are five objects (out of 20,000) that have light curves that would suggest a shape up to an axis ratio of about 7-8 to 1," Dr Meech told BBC News. Link at end of BBC article will take you to an 'accelerated article preview' allowing access without the paywall.Agmartin (talk) 19:53, 20 November 2017 (UTC)

Nope, that's a spaceship for sure. AllGloryToTheHypnotoad (talk) 14:11, 21 November 2017 (UTC)

A2017U1 5gsmoothWHT.jpg

Original image

Enhanced version

Which part of File:A2017U1 5gsmoothWHT.jpg (shown above) is ʻOumuamua? Please clarify in the image caption; and in the description on Commons. Andy Mabbett (Pigsonthewing); Talk to Andy; Andy's edits 00:15, 21 November 2017 (UTC)

 Done Description now reads, "1I/ʻOumuamua, imaged with the 4.2 meter William Herschel Telescope in the Canary Islands on 28 October 2017, is seen as a stationary light source in the centre of the image. Background stars appear streaked because the telescope is tracking the rapidly moving asteroid." nagualdesign 22:30, 21 November 2017 (UTC)

I've also uploaded an enhanced image that shows ʻOumuamua more clearly, and swapped it with the image in the article. Not sure if that's the done thing. Feel free to revert. nagualdesign 23:02, 21 November 2017 (UTC)

@Nagualdesign: Thank you; just what I wanted. Andy Mabbett (Pigsonthewing); Talk to Andy; Andy's edits 10:46, 23 November 2017 (UTC)

Missing dates

In the text:

The object continued to speed up until it went through perihelion, where it peaked at 87.7 km/s.[7] By the discovery date it had slowed down to 46 km/s and will continue to slow down until it reaches a speed of 26 km/s relative to the Sun. This interstellar speed is within ~5 km/s of other stars within the Sun's stellar neighborhood, which also indicates an interstellar origin.[24] The object will ultimately head away from the Sun at an angle of 66°[n 11] from the direction it came from. As it leaves the Solar System...

when are:

1. will continue to slow down until it reaches a speed of 26 km/s
2. The object will ultimately head away from the Sun
3. As it leaves the Solar System

calculated to occur? Andy Mabbett (Pigsonthewing); Talk to Andy; Andy's edits 00:24, 21 November 2017 (UTC)

There is a table in the article that shows by the year 2430 it will be 2300AU from the Sun and going 26.32km/s. 2300AU is 76 times further than the planet Neptune. But do you define the edge of the Solar System (Oort cloud) as 100000AU or 200000AU? It is already heading away from the Sun and leaving the Solar System. -- Kheider (talk) 01:18, 21 November 2017 (UTC)

Thank you, but to a lay person such as me, the meaning of that table is opaque. If the object is already heading away from the sun, why does the article say it will ultimately (future tense) do so? Andy Mabbett (Pigsonthewing); Talk to Andy; Andy's edits 10:45, 21 November 2017 (UTC)

26 km/s is the velocity it will have when it leaves the gravitational influence of the Sun in the distant future. It is referred to velocity at infinity or the hyperboic excess velocity (sorry math) if you want to google a more detailed explanation. Agmartin (talk) 17:28, 21 November 2017 (UTC)

Thank you, but my point was (and remains) that this needs to be clarified in the article. Andy Mabbett (Pigsonthewing); Talk to Andy; Andy's edits 10:48, 23 November 2017 (UTC)

Let us generically define the edge of the Solar System at 120000AU, note that an Astronomical unit = 149597870.7 km, and that the comet is moving at 26.33 km/s. It will take the comet 20000 years to get that far. Math: 120000AU / 26.33 / 60 seconds-per-min / 60 min-per-hour / 24 hr-per-day / 365.25 days-per-year = 21604 years -- Kheider (talk) 18:34, 21 November 2017 (UTC)

Should the 1I prefix be in the title?

Kaldari removed it based on WP:COMMONNAME, but we already have a lot of precedents for putting in official designations (e.g. 17P/Holmes for comets, 385446 Manwë for minor planets, etc.), so I think it should be discussed here. Personally I am in favour of consistency (so reinstating the "1I"), but I would think that editors more active in astronomy than I would be more qualified to weigh in here. Double sharp (talk) 02:56, 21 November 2017 (UTC)

@Double sharp: The title of 17P/Holmes is actually Comet Holmes, so that's not a good example of using the official designation. We typically use the common name rather than the official designation unless disambiguation is needed (which is true of many comets and almost all minor planets), but not ʻOumuamua. Comets: Halley's Comet, Comet Encke, Biela's Comet, Comet Kohoutek, but 4P/Faye, 5D/Brorsen, etc. Minor planets: Makemake, Haumea, but 4 Vesta, 78 Diana, etc. Kaldari (talk) 03:16, 21 November 2017 (UTC)

@Kaldari: Okay, so I messed up my example; but it seems we also have 67P/Churyumov–Gerasimenko, which hardly needs disambiguation, for example. And FWIW, the MPC gives "Correct forms for referring to this object are therefore: 1I; 1I/2017 U1; 1I/ʻOumuamua; and 1I/2017 U1 (ʻOumuamua).", so it appears that the I-number is considered more primary than the name. So I am not entirely sure which way we should go here, which is why I opened it for discussion while only leaning towards and not quite taking a side. Double sharp (talk) 07:22, 21 November 2017 (UTC)

Unfortunately the use of 1l/ʻOumuamua seems to be a lot less than ʻOumuamua. However Oumuamua use is much more common for this without the "ʻ" character. Graeme Bartlett (talk) 10:57, 21 November 2017 (UTC)

Incorrect flight path

The drawing shows a path around a sun sized mass located between earth and the sun. So it’s either an error or the ship is accelerating. Looks like they were just passing therough.

Info @ The ubie . com

72.94.235.218 (talk) 04:47, 21 November 2017 (UTC)

Not sure what drawing you are talking about. But the two diagrams used in the article show perihelion just inside the orbit of Mercury. The asteroid accelerated up to perihelion passage as it fell towards the Sun. All heliocentric objects have their peak speed at perihelion. -- Kheider (talk) 06:20, 21 November 2017 (UTC)

I'll agree this diagram File:A2017_U1_orbit-Oct25_2017.png doesn't look like the sun is at the focus of an hyperbola, but I'm willing to give it the benefit of the doubt, and that perspective is causing this apparent misalignment. Tom Ruen (talk) 09:38, 21 November 2017 (UTC)

Here's a quick sim I made of a fictitious comet. The perspective is rotating around the Sun to show that the Sun does not always appear to be at a focus even though it is: http://orbitsimulator.com/gravitySimulatorCloud/simulations/1511282592724_wikiDescription.html — Preceding unsigned comment added by Tony873004 (talk • contribs) 16:49, 21 November 2017 (UTC)

Is it 'now' or 'not'?

"The Carina–Columba stellar association is now very far in the sky from the constellation Lyra, ..." Do we mean _not_ very far? Rhodesh (talk) 06:13, 21 November 2017 (UTC)

45 million years ago all the stars in the sky where in VERY different locations. Carina Nebula is currently deep in the Southern hemisphere with a declination of −59. -- Kheider (talk) 06:25, 21 November 2017 (UTC)

Holy cow!

It's not likely a coincidence that the first proved interstellar object should have such a large axis ratio, is it? It just begs to be considered of artificial origin and thus proof of extraterrestrial life having existed; its spectra would just be that or the coating of gunk it's accreted on its journey through space.

If we had any kind of decent space program, we'd capture this thing and study it! — Preceding unsigned comment added by 73.164.86.121 (talk) 11:07, 21 November 2017 (UTC)

All imaginations will certainly be let loose on this one, and we may never know much more. The 10:1 ratios are crazy, but not proven. The newly added artistic imagery really needs severe warnings. Tom Ruen (talk) 11:57, 21 November 2017 (UTC)

Have to admit the 10 : 1 ratio made me think artificial, or at least very strange. If it is artificial then its been dead for a very long time. Also its not stopping here, if it was going to take a stop here it would have started breaking before perihelion. Fascinating object. :D Lucien86 (talk) 13:21, 21 November 2017 (UTC)

Ferenges saw no opportunity in our system. BatteryIncluded (talk) 13:24, 21 November 2017 (UTC)

Beside the fact that 10:1 can only suggest "artificial" to some entities having ten fingers (i.e. entities having any fingers at all in the first place), the last figures are "approximately 180 × 30 × 30 meters", that is a 6:1 ratio, exactly the length/width ratio of the Northern pike (without caudal fin, which has been certainly burned passing near some sun on the way). 194.174.76.21 (talk) 13:59, 21 November 2017 (UTC) Marco Pagliero Berlin

It's more likely to be a spaceship than a fish. Alternately, this might prove that the aliens are fans of Canadian band The Northern Pikes, whose album came out 33 years ago and was thus accessible to aliens listening to Canadian radio stations within a few light years of Vega. AllGloryToTheHypnotoad (talk) 14:14, 21 November 2017 (UTC)

Doing too much thinking here. Given calculated mass, assuming rocky composition, and given spin rate, and average tensile characteristics of "natural" space rocks, is is possible it could have maintained that shape over all these years? Kortoso (talk) 18:41, 21 November 2017 (UTC)

The suggestion provided is that it formed out of a spray of molten gloop from a planetary collision, which then froze in space. I assume the gloop would have to be iron-nickel, since if it's silicates or ices you still end up with the same problem, with torque breaking it up. Personally I think the only way you get a structure with a 10:1 ratio surviving for thousands of years is by engineering it, and thus it's a spaceship. I'm buying guns and gold. AllGloryToTheHypnotoad (talk) 23:44, 21 November 2017 (UTC)

It likely contains metal for integrity, but a fragment of a planetary core (molten gloop) needs not to be engineered (see 16 Psyche), so creation cannot be invoked... unless it is a leftover from a planet destroyed by a Death Star. BatteryIncluded (talk) 23:58, 21 November 2017 (UTC)

Maybe a voyager from E.T. --Zumthie (talk) 00:20, 22 November 2017 (UTC)

Please, AllGlory: The aspect ratio is 6:1 and not 10:1 and a rotation period of 7 to 8 hours is really rather sleepy. Beside that it is not very likely that the rotation axis is perpendicular to the long axis of the body, but even then I find for a diameter of 180 meters a peripheral speed of 1,17 meters per minute, that doesn't seem to produce much centrifugal force 194.174.76.21 (talk) 11:17, 22 November 2017 (UTC) Marco Pagliero Berlin

I'm not talking about torque from rotation. There will be a torque across that body from external forces acting on it (e.g. its hyperbolic swing around the sun), and a torque will go across that body whenever it gets hit by another body. Something that skinny should break before it ever gets to us... unless, of course, it's a spaceship engineered by aliens. AllGloryToTheHypnotoad (talk) 23:38, 22 November 2017 (UTC)

Actually, the physics of rotating bodies is such that the rotation axis must be perpendicular to the long axis. Don't want to misinform the readers, even if it is only a talk page. 79.64.186.151 (talk) 20:03, 22 November 2017 (UTC)

For comparisons there's near-earth asteroid 2003 SD220, 1000-2000m long, and observed in radar in 2015 [1], and it'll be even closer (8LD) in December 2018. If we want to send out an exploratory spacecraft, this target is infinitely easier to reach. Tom Ruen (talk) 13:12, 22 November 2017 (UTC)

NOTE TO ALL-this entire thread is nothing more than WP:FORUM violation and should have been deleted by the observing administrator. Engaging in such a post just encourages this sort of nonsense. 104.169.28.113 (talk) 09:51, 23 November 2017 (UTC)

Better watch out for this guy. I wouldn't want to see what he's like when he's angry! 65.175.250.233 (talk) 08:53, 24 November 2017 (UTC)

Ooh! An IP is angry! AllGloryToTheHypnotoad (talk) 14:04, 26 November 2017 (UTC)

alien spaceship

Couln't it bee an alien spaceship? --82.113.121.246 (talk) 07:53, 23 November 2017 (UTC)

Yes it could. However, since it's travelling on a ballistic trajectory like rocks do it's either lacking any means of propulsion or it's just completely dormant for some reason. Maybe the nacelles fell off (along with the saucer section)? nagualdesign 08:21, 23 November 2017 (UTC)

Please don't engage WP:FORUM and respond nonsensically to posts like this, Nagual. — Preceding unsigned comment added by 104.169.28.113 (talk) 09:59, 23 November 2017 (UTC)

How dare you say that it was nonsensical! I'll have you know that my response was well-reasoned.

Sometimes editing Wikipedia begins with talk page discussions. And sometimes having a bit of Q&A here can stop unnecessary edits from happening in article space. I expect a lot of readers are wondering the same thing, but having a section on What ʻOumuamua isn't doesn't really work.

Besides, it isn't like we're just shootin' the breeze here. If 82.113.121.246 responds with "Well then, perhaps the article should say such and such.." then WP:FORUM doesn't apply. nagualdesign 10:22, 23 November 2017 (UTC)

Nature article

A free version of the article is available. Agmartin (talk) 17:39, 21 November 2017 (UTC)

Thanks. -- The Anome (talk) 18:05, 21 November 2017 (UTC)

Fantastic

This is a fantastic discovery. Am I the only person who read the name and also thought of "Papa-Oom-Mow-Mow"?

Well I for one thought of "Surfin' Bird" for much the same reason.[2] nagualdesign 21:07, 21 November 2017 (UTC)

Size

This article is missing all information on the object's size. -173.187.77.148 (talk) 00:57, 22 November 2017 (UTC)

the size matters.

just put size is intergalactic ... from another galaxy: Are all of you still against original thinking ?

but if not, according to my calc (if spherical) it be a bal quoter kilometre across with mass > 8 Mton < 10e10 kg

— Preceding unsigned comment added by 99.90.196.227 (talk) 02:41, 22 November 2017 (UTC)

I doubt that many of the editors here are against original thinking! However, Wikipedia doesn't permit original research, if that's what you're trying to ask.

I'd say you're probably thinking so far outside the box here that the box must be nearing your cosmological horizon. ʻOumuamua is travelling at approximately 0.0000878 c. The nearest galaxy, Andromeda, is around 2.537 million light years away. By my calculation, if ʻOumuamua came from Andromeda it would have to have been travelling for over 28 billion years; more than twice the age of the Universe.

I'm sure that your calculations of ʻOumuamua's mass are 100% reliable though. And a bal quoter kilometre across, you say? I expect someone will add that info to the article at some point. Thank you for your contribution. nagualdesign 04:09, 22 November 2017 (UTC)

If it was intergalactic it would be moving another 10 times faster: Oort cloud = ~2km/s, galactic disc = ~20km/s, intergalactic = ~200km/s. -- Kheider (talk) 05:55, 22 November 2017 (UTC)

`nagualdesign :N' calculation may contain systemic bias since empirical search indicating a lot of sources 3.57e-13 x earlier about:'Obuamua recent origin. You just assume and not state why; why you assume constant speed during 2 Universe lifetimes. Are you shure tehere were about Andromeda Galaxy? We should add section about fake news like above weather.com. It will benefit 500 x more readers (see:alexa rank) who may be cyberneted by oogle&a to from another galaxy dezinfo. — Preceding unsigned comment added by 99.90.196.227 (talk) 08:30, 22 November 2017 (UTC)

I assure you that there was no systematic bias in my calculation, since it was just basic arithmetic. I was also pretty clear about the basic assumptions I was making (ie, assuming a constant velocity over a fixed distance). The truth is that Andromeda didn't exist 28 billion years ago, so the equation makes no sense. In case it isn't obvious, my comment wasn't intended to be taken entirely seriously. I was poking fun at the fact that you'd confused interstellar (from another star system within the Milky Way) with intergalactic (from another galaxy), without considering the vast difference in scale that this would imply. Galaxies are around 5 orders of magnitude more distant than stars of the Milky Way. nagualdesign 20:26, 22 November 2017 (UTC)

from whence

The article is locked so I can't do this myself, but "from whence" is just ridiculous english trying to sound educated. Whence literally means "from where" so from "from whence" means "from from where". Someone with editing-rights should correct that. — Preceding unsigned comment added by 217.254.45.23 (talk) 15:33, 22 November 2017 (UTC)

It may be technically redundant, although writers have used "from whence" for centuries. The article currently says "from the direction from whence it came" which does sound like something from the Department of Redundancy Department. Jonathunder (talk) 16:46, 22 November 2017 (UTC)

I rephrased it to "from the direction of its approach." Jonathunder (talk) 16:52, 22 November 2017 (UTC)

Verily I say unto thee; Lord, what fools these mortals be! Everything has beauty, but not everyone can see. But, for my own part, it was Greek to me.

Only kidding. I don't think anybody was "trying to sound educated" any more than using 'long words' is the sole dominion of sesquipedalianists. "From whence" is perfectly good English, but alas... nagualdesign 22:45, 22 November 2017 (UTC)

Table: Inbound velocity at 200 AU from the Sun

What is the significance of this table in the Observations section? I see no references to this table from the text. Boardhead (talk) 14:34, 23 November 2017 (UTC)

It is produced with JPL Horizons. What it shows is that no other known object comes even close to matching the inbound velocity of Oumuamua. All of them are ~3 km/s inbound at 200 AU from the Sun while Oumuamua is 26.5 km/s (10x greater). The velocity at infinity (near infinity) is what is what is most notable about Oumuamua. Most of these objects are well known. -- Kheider (talk) 15:45, 23 November 2017 (UTC)

Thank you for this information. It sounds like you are stating this is a list of the highest-velocity objects yet discovered in the solar system. It would be useful to state this in the article. Boardhead (talk) 17:45, 23 November 2017 (UTC)

Evidence of interstellar origin

Does the section ʻOumuamua#Evidence of interstellar origin say anything that is not already covered in the article? -- Kheider (talk) 21:55, 21 November 2017 (UTC)

In a word, no, but maybe 23h112e will have something to say about that. nagualdesign 22:23, 21 November 2017 (UTC)

What is the curent position of head of US gov. about 'O origin ? — Preceding unsigned comment added by 99.90.196.227 (talk) 08:34, 22 November 2017 (UTC)

He probably thinks very little about it. I wonder what the pope thinks? Or Bruce Willis? nagualdesign 22:17, 22 November 2017 (UTC)

@Kheider:

Yes, it is simply for those who react with incredulity to the statement of an object being known as a fact as originating from somewhere outside of the solar system, which includes those who aren't practicing routine astronomical observation, and those without degrees in allied subjects (those whose minds are therefore consequently oriented to ways of thinking about things which predisposes them to find understanding astronomical and astrophysical subjects less easy), i.e. a synopsis for people who can't or don't want to sift through the data and terminology and want only to see the proof, for instance those who have employments and are time-pressured by other commitments but are interested because of the historical importance and are interested due to the fact of the article being on the opening page yesterday and today. 23h112e (talk) 17:29, 22 November 2017 (UTC)

---

source: http://www.skyandtelescope.com/astronomy-news/astronomers-spot-first-known-interstellar-comet/ "...the fact that A/2017 U1 is coming from a spot only 6° from the solar apex, the direction that our Sun is moving (at about 20 km/s) through its interstellar neighborhood and thus, statistically, the most likely incoming direction for an interstellar visitor..."

& source: Stephen Webb Measuring the Universe: The Cosmological Distance Ladder p.118

How this fact indicates the greater likelihood of interstellar orign. 23h112e (talk) 17:43, 22 November 2017 (UTC)

Now that the section is being fleshed out I agree that it's a good idea to have a specific section for those looking for what the actual evidence is. It also means that the more technical details have a nice home while the lead section can avoid baffling 90% of readers. I must say though, 23h112e, that claiming anything to be known as a fact is not a very scientific point of view. There is good evidence - strong evidence - but that is all. And that's more than enough. nagualdesign 22:17, 22 November 2017 (UTC)

The Velocity at infinity (or at least near infinity) is what is most important. Eccentricity is just a function of the perihelion point. If perihelion was further out the eccentricity would be notably greater. -- Kheider (talk) 03:09, 23 November 2017 (UTC)

What's also interesting isn't just a significant v_∞ but that it passed so close to the sun, so nearly 100% of its initial kinetic energy was radial, directed nearly exactly at the sun. So it was a literal bullseye into our solar system, from where ever it came. Coincidents happen but mainly if we someday find out hundreds of similar sized objects with hyperbolic trajectories are annually passing through the solar system, but we've just been missing them. Tom Ruen (talk) 17:57, 23 November 2017 (UTC)

With a Geometric mean diameter of less than 100 meters, Oumuamua would simply have been too faint for automated software to detect if it had passed much further from the Earth. I do expect automation to start detecting many of these in the next ten years or so as surveys become more sensitive. -- Kheider (talk) 18:50, 23 November 2017 (UTC)

Extrasolar versus interstellar

The section on Evidence of interstellar origin currently begins with:

Evidence of interstellar origin

By mid November 2017, astronomers were certain that it was of extrasolar origin...

I find this apparent minor contradiction a little irksome. The word extrasolar might be defined as "orbiting a star other than the Sun", and the Extrasolar object article pretty much confirms that. While interstellar means "occurring or situated between stars". I suppose, at a push, they're pretty much synonymous in this context but it seems kind of funky to me. ʻOumuamua came from interstellar space, we can be certain of that. And asteroids form within the accretion discs of stars, right? But how certain are we really that ʻOumuamua once orbited another star?

I would have simply edited the sentence in question to read, "By mid November 2017, astronomers were certain that it was of interstellar origin...", but origin also denotes "the point where something begins". I also note that, according to Extrasolar object, the only known extrasolar asteroid is in orbit around GD 61, whereas ʻOumuamua is the only known hyperbolic asteroid.

In short, as a merciless pedant I would probably describe ʻOumuamua as "an interstellar object of extrasolar origin" since, as far as I'm aware, asteroids don't form in interstellar space. So now I'm thinking that we should change any instance of "interstellar origin" to "extrasolar origin", including the section title.

Any thoughts? nagualdesign 08:13, 23 November 2017 (UTC)

I agree. Tom Ruen (talk) 17:42, 23 November 2017 (UTC)

I see that the article has been reconfigured to good effect in my absence. Thank you to whoever did that. I made a couple more minor amendments so that the article was consistent with the references while satisfying the reasoning outlined above. I for one will sleep easier tonight. Keep up the good work! nagualdesign 03:30, 24 November 2017 (UTC)

Exiting the Solar System?

Since I'm not a scientist, I'm not clear on why the object is expected to exit the Solar System. I would expect it to be affected by the Suns gravity, and be captured by it, causing it to fall into an orbit. Why the object is not likely to do that is not explained in the article. Can someone with a little expertise in these matters clarify that? Thanks. Juneau Mike (talk) 14:49, 22 November 2017 (UTC)

Note 13 of the Table "1I/'Oumuamua velocity with respect to the Sun" explains this. When outbound 1AU from the Sun, the object was going 49.67 km/s with respect to the Sun. But to be captured by the Sun's gravity it would need to be moving less than 42.1219 km/s at 1AU. (I had not added this directly to the article as I wanted to avoid any appearance of Wikipedia:No original research. But I went ahead and was Wikipedia:Be bold.) -- Kheider (talk) 16:18, 22 November 2017 (UTC)

It's nothing more than Escape velocity, but perhaps Conservation of energy is involved too, changing Gravitational potential energy into Kinetic energy and back into potential energy when it leaves. Tom Ruen (talk) 18:19, 22 November 2017 (UTC)

@Kheider: Sorry to be a stick in the mud but I recommend against including any OR. As Tom mentioned, it's a simple case of ʻOumuamua exceeding the Sun's escape velocity, and this way of explaining it is also more accessible than talking about calculated velocities at particular distances. nagualdesign 20:36, 22 November 2017 (UTC)

I made the edit. If any reader wishes to know more about the specifics they can visit Escape velocity. If you'd prefer to keep it as it was you might be able to copy/paste a reference from here. nagualdesign 21:29, 22 November 2017 (UTC)

I swapped a paragraph from the lead with one from Evidence of interstellar origin (diff) per MOS:INTRO. I hope that helps make the article more accessible, while providing the specifics for those who want to weigh up the evidence themselves. nagualdesign 22:06, 22 November 2017 (UTC)

Escape velocity explains what is happening quite well. I appreciate several of you answering my question. Thanks! Juneau Mike (talk) 20:51, 24 November 2017 (UTC)

Voyager 1

In the article, it says the asteroid is expected to 'leave the solar system' in about 20000 years. Given the velocity, would that exit not be expected to be much sooner? Voyager already left the solar system, and its velocity is not many orders of magnitude larger than the comet. — Preceding unsigned comment added by 198.202.130.252 (talk) 08:09, 23 November 2017 (UTC)

Actually Voyager 1 has NOT left the Solar System. It has passed the heliosphere, but is well inside the Oort cloud. I was annoyed when press releases described it as such. Voyager 1 is only 141 AU from the Sun and thus has ~100,000 AU to go. Nemesis (hypothetical star) was suppose to orbit 95,000 AU from the Sun. The comet's ($v_{\infty }\,\!$=26 km/s) while Voyager 1 is only going 17 km/s. -- Kheider (talk) 09:29, 23 November 2017 (UTC)

Exit Date?

In the opening, it says the object is expected to leave the solar system in about 20,000 years. Lower down, it says the object left the solar system on 20 November. ??? — Preceding unsigned comment added by 202.246.252.97 (talk) 00:24, 24 November 2017 (UTC)

I have removed the misleading text. I am not even sure that lead paragraph in the Observations section does anything useful. -- Kheider (talk) 05:33, 24 November 2017 (UTC)

Many names confusing

Is the official, formal or systematic name 1I/ʻOumuamua or 1I/2017 U1 (ʻOumuamua)? (See the last line in the lead and section Naming_of_comets#Current_system.) And since we have a nomenclature section, shouldn't the alternate names, including previously designated like C/2017 U1, be put down there?

Once we've settled that, should Wikipedia call it 1I/ʻOumuamua or ʻOumuamua? Both designations have about the same number of occurrences in the article. Unless there is some special reason for calling it 1I/ʻOumuamua in one sentence and then simply ʻOumuamua in the next, we should reduce the spelling to one form, both in the article and in all the other Wikipedia articles that mention it.

I guess this would be a formal consensus-building discussion: should we have one name for one object and, if so, what name should it be? --RoyGoldsmith (talk) 21:03, 23 November 2017 (UTC)

 Done - FWIW - found/replaced instances of 1I/ʻOumuamua with ʻOumuamua - to be consistent - *entirely* ok w/ me to rv/rm/ce edit if not ok of course - hope this helps in some way - in any case - Enjoy! :) Drbogdan (talk) 13:47, 24 November 2017 (UTC)

Reverted as it is probably better to be more selective instead of a universal search and replace. "'1I/ʻOumuamua" is still the current name and we should certainly not be changing reference titles. It might make sense to call it "1I/ʻOumuamua" during the first occurrence of each section. I also think tables should use the more formal (longer) name especially when there is plenty of room in a column. In other articles, I think the proper name 1I/ʻOumuamua should be used (at least during the first mention). Having said that I do not see why Wikipedia NEEDS to define a hard rule for this. -- Kheider (talk) 14:09, 24 November 2017 (UTC)

I think we should stick with the common name 'Oumuamua (WP:COMMONNAME), which is the name that now seems to be used by the popular press, e.g., The New York Times. Meech et al refer to the object only once with the MPEC form "1I/2017 U1 ('Oumuamua)" and consistently thereafter simply use 'Oumuamua. That's surely an acceptable name to use for this object. Of the older designations, "A/2017 U1" is still found on some web pages, so at least "1I/2017 U1 ('Oumuamua)" and "A/2017 U1" should probably be mentioned as formal and former names respectively in the lead. All the other forms of the name could be included in the nomenclature section. I haven't seen "1I/'Oumuamua" used all that often, but I haven't looked at all the sources. --Robert.Allen (talk) 17:39, 24 November 2017 (UTC)

I agree that common names work better in prose, since "1I/ʻOumuamua" is jarring to the internal monologue. Even worst if you try to read the article aloud. I suggest that (if I'm not already late to the party) all instances should be changed to ʻOumuamua in prose, tables and other instances should follow the style of the references perhaps, and of course the references themselves should be left verbatim. nagualdesign 19:09, 24 November 2017 (UTC)

We should treat this the way we do Ceres (dwarf planet) or 4 Vesta, which are featured and good articles, respectively. After the first sentence, where full names are given, use just the short common one. It's similar to what we do for people or places. Jonathunder (talk) 19:35, 24 November 2017 (UTC)

I have noted that many people love to expand comet names like C/1980 E1 to C/1980 E1 (Bowell) when editing Wiki articles. Not saying that is important, but just an observation I have made. I have left "1I/ʻOumuamua" in the 200 AU table because all of those objects are listed by their formal names. -- Kheider (talk) 19:39, 24 November 2017 (UTC)

I'm just saying that two names for the same object is confusing, especially for non-astronomers. According to MPEC 2017-V17, the permanent designation is "1I" alone; the common name will be "ʻOumuamua". (The IAU regards designations as different from names.) 1I/2017 U1; 1I/ʻOumuamua and 1I/2017 U1 (ʻOumuamua) are correct forms for referring to this object. A/2017 U1 and C/2017 U1 are previous designations.

I'm starting a poll in the next subsection, to build consensus or not for this topic. This is not a vote. It is merely an attempt to see where people stand as of right now.

Further discussion about this topic should be placed here immediately before the Consensus building subsection. Actually votes and their explanation should go on the other side.

Further discussion goes here vvv --RoyGoldsmith (talk) 23:45, 25 November 2017 (UTC)

I only see the name "2017 U1" mentioned in historical context. It is fine having 2017 U1 in the "Asteroidal nature" section since that was when the object was first discovered and did not have a formal name. That section is also largely about why it changed from being "C_omet/" to an "A_steroid/". -- Kheider (talk) 01:50, 26 November 2017 (UTC)

Consensus building

This side (subsection) contains a poll of two topics:

1. Should we have one name for the object defined in this article (other than the first sentence in the lead and the Nomenclature section)? and
2. If so, what is that name?

The title of the Wikipedia article (currently ʻOumuamua) we'll leave until we have some more opinions on these first two points.

•  Yes - ʻOumuamua. Because of WP:COMMONNAME and examples Ceres (dwarf planet) and 4 Vesta. --RoyGoldsmith (talk) 23:57, 25 November 2017 (UTC)

•  No - It is also appropriate to call it 2017 U1 in the "Asteroidal nature" section since that was when the object was first discovered and did not have a formal name. It was also changed from a "C_omet/" to an "A_steroid/". I think a more proper comparison would be 1P/Halley. I think the naming issue has already resolved itself. -- Kheider (talk) 01:50, 26 November 2017 (UTC)

• I think it should be referred to as ʻOumuamua in most of the article, per WP:COMMONNAME. No opinion on the Asteroidal nature section. Kaldari (talk) 03:42, 26 November 2017 (UTC)

• Comment - Without wishing to disparage your efforts, Roy, since consensus building is a laudable endeavour, I think we've already resolved this issue. You made your case at the start of this section (before this subsection) and Kheider, Robert.Allen, myself and Jonathunder all responded. (And Kaldari agrees.) The consensus was that we should follow WP:COMMONNAME and stick with ʻOumuamua for the name of the article, as well as in prose, while there are a small number of places where the official designation is more appropriate. I'm not sure what you're going to achieve by putting this to a !vote. All (or most) discussions on Wikipedia talk pages are a form of consensus building, without having to explicitly state that they are in some way 'official'. If you strongly disagree with a small number of editors and seek further input from the wider community you could try a request for comment, where the final consensus might carry more weight. A better idea in this case might be to form a more convincing argument. I'd certainly be willing to change my mind, or to have it changed, if I found your case compelling. With all due respect I don't think you've done that here. Sincerely, nagualdesign 17:08, 26 November 2017 (UTC)

• I'm sorry. The number of "misspellings" had gone down greatly in the last 24 or 48 hours before I wrote this but I didn't notice it. The alternate form "1I/ʻOumuamua" only exists now only as the last line in the table "Inbound velocity at 200 AU...". Should it be changed to ʻOumuamua? --RoyGoldsmith (talk) 23:39, 26 November 2017 (UTC)

• Kheider gave a good reason for leaving the table the way it is. Jonathunder (talk) 10:29, 27 November 2017 (UTC)
• Ditto. The left-hand column of that table ("Object") lists designations (with names written in parentheses if they are not part of the designation). nagualdesign 16:51, 27 November 2017 (UTC)

Votes go here ^^^ --RoyGoldsmith (talk) 23:45, 25 November 2017 (UTC)

Anybody here know any Hawaiian?

The etymology in the Nomenclature section currently reads, "The name comes from Hawaiian ʻou.mua.mua 'scout', (from ʻou 'reach out for' and mua, reduplicated for emphasis​ 'first, in advance of')." When I added the ʻou.mua.mua I was copying what the reference says verbatim, but now that it's linked to Wiktionary where the word is written as ʻoumuamua I'm wondering if the full stops, or whatever they are, should be removed. Any ideas? nagualdesign 17:18, 27 November 2017 (UTC)

Oort Cloud

Given that the Oort cloud is the cosmographical boundary of the Solar System, are there any citations as to when it leaves the outer limits of said system? kencf0618 (talk) 18:43, 26 November 2017 (UTC)

Not really as many authors define it somewhat differently. The boundary of the Oort cloud is in constant flux as the outer edge is only loosely bound to the Solar System and subject to perturbations by the galactic tide and passing stars. -- Kheider (talk) 18:57, 26 November 2017 (UTC)

ʻOumuamua certainly entered the inner solar system though within the orbit of Mercury, and exited it within the orbit of Mars. It'll be very interesting to see what Pan-STARRS observes over time! kencf0618 (talk) 18:19, 27 November 2017 (UTC)

Just out of curiosity: 'Oumuamua is inside the orbit of main-belt asteroid Ceres (aphelion: 2.97AU) from mid May 2017 to early Jan 2018. And if we are lucky 'Oumuamua might show some cometary activity while outbound over the next month. -- Kheider (talk) 18:50, 27 November 2017 (UTC)

The name

Perhaps there should have been a nod at Rendezvous with Rama. 89.197.114.132 (talk) 16:17, 24 November 2017 (UTC)

Yes, there are some good sources for this: e.g., [3], [4]. --Robert.Allen (talk) 17:59, 24 November 2017 (UTC)

The second link "The thing is that the story seems awfully prescient. A/2017 U1 has hurtled in on the sort of trajectory Clarke envisaged for Rama. In Rama’s case, it was intentionally done to maximise the ‘slingshot’ effect – getting a free speed boost from the Sun’s gravity well." ... we'd definitely have some great circumstantial evidence of "intelligent design" if the outbound direction corresponded to a known neighboring star, and if NOT, perhaps we'll discover one if we look very carefully in that direction! Also since we didn't see it before perihelion, we don't actually know if there were any course corrections that helped guide its final approach, and its direction of origin might not be safely extrapolated backwards from its current trajectory. Tom Ruen (talk) 19:45, 24 November 2017 (UTC)

Course corrections, eh? Hah! The idea's pretty fanciful but not outside the realms of possibility, I suppose. If you'd like, and if others don't disagree, perhaps you'd like me to add a row of windows to the artist's impression in the infobox? (Not really!) nagualdesign 20:46, 24 November 2017 (UTC)

I wasn't thinking windows, but a radio dish would certainly help us figure out where it really came from. [5] Tom Ruen (talk) 21:19, 24 November 2017 (UTC)

It's my understanding that a hyperbolic trajectory can either speed up or slow down a given orbit. Does anyone know whether the I1's trajectory got faster or slower as it passed by the sun and by how much? If significant, this could be put in the article. --RoyGoldsmith (talk) 00:16, 26 November 2017 (UTC)

The speed is basically the same inbound and outbound. ==> "Its incoming and outgoing speeds as it went through interstellar space were 26.33 +/- 0.01 km/s." -- Kheider (talk) 00:22, 26 November 2017 (UTC)

User:RoyGoldsmith, do you mean like a Gravity assist? The inbound speed and outbound will be equal in the frame of reference of the assisting body (sun), but since the direction is changed, there can be change in relative speed from another frame, like a star of origin. Tom Ruen (talk) 03:21, 26 November 2017 (UTC)

I too wonder if it got a gravity assist (slingshot), as it is so common with interplanetary spacecraft. If not, why it did not happen? Perhaps other readers (and editors) would like to see a line explaining that? Cheers, BatteryIncluded (talk) 17:58, 26 November 2017 (UTC)

As I understand it, it all depends on the trajectory of ʻOumuamua relative to the trajectory of the Sun. The last sentence of the lead currently reads, "The direction of motion of ʻOumuamua is 6° from the solar apex." so I expect it did get a kick. The only problem is that if someone here performs the calculation it wouldn't be admissible (per WP:OR) and there seems to be a dearth of reliable sources on this specific topic. nagualdesign 18:20, 26 November 2017 (UTC)

What is needed, as in other cases, is 'WP - the extended version' - a certain number of parallel articles where OR is included, 'material known to be accurate' is presently only in blogs and suchlike (we all have our own examples). Jackiespeel (talk) 22:13, 26 November 2017 (UTC)

I'm only saying that, with 40-plus days of observation arc, the course (including the instantaneous velocity of each point) should be well known. Is the total energy of ʻOumuamua after perihelion greater or less than the total energy before the fly-by? If ʻOumuamua has more energy after then the sun will have transferred some energy into the object and we've increased our orbital eccentricity. However, if it has less energy then we've lessened our eccentricity (say from 1.2000002 to 1.2000001). One can imagine a race of Krell (from Forbidden Planet) precisely throwing a rock so that it will, after dozens or hundreds of fly-bys, each one giving up a minute fraction of its speed, be captured (eccentricity < 1) by some star in another arm of the galaxy a billion years from now. --RoyGoldsmith (talk) 00:41, 27 November 2017 (UTC)

I imagine something more like something breaking off from the stress of the close solar encounter. That could change its momentum and direction. Unfortunately we have no observations near perihelion to know anything about its inbound orbital parameters. Everything there is extrapolating backwards assuming there was no change. Tom Ruen (talk) 20:36, 27 November 2017 (UTC)

Speed discussion

Somewhere this name section turned into a speed discussion. It looks like from the JPL Horizon data that the outbound velocity is minutely less than inbound. I am not sure of the physics but a close encounter between two moving masses should result in some transfer of kinetic energy. The amount is more apparent in the smaller mass. Did one of the references say that the trajectory was "retrograde"? I think this results in a slowing. P.S. the trajectory need not be hyperbolic.User-duck (talk) 12:50, 28 November 2017 (UTC)

2017 U1 had a flyby delta-V of about (26.32824 - 26.34089) or -12.7 m/s. So 2017 U1 lost a small amount of speed. -- Kheider (talk) 12:52, 29 November 2017 (UTC)

Argument of periheilion (link and definition)

The link for Argument of perihelion connects to "Argument_of_periapsis".

And the number given 241.7 seems to indicate day 245.2290617 of the solar year.

Shouldn't that be September 2 @ 5:29:50?

Can someone explain the number?

info@ the Ubie . com -- 72.94.230.198 (talk) 20:04, 30 November 2017 (UTC)

trajectory should be where it came from and where it is headed. there seems to be a discrepancy in the argument of periheilion sugesting it passed the sun a few days earlier.. sep 4 or so. BUT WHERE are the ORIGIN CORDINATES? (i use caps for flair and do not follow the millenial convention that they mean shouting.) -- 72.94.230.198

i think its presumptoious to call it a scout or name it after obama. it appears to be a giant footlong hotdog ( and the same color) which is extreemly freeky and if the sd220 photo is in fact the object, then it looks like a telescope. though perhaps with some artificial beings to keep it in repair. yet the time it has been out there sugests that it may simply host artificial life. we float in space here. they float in space there. you can see some of the contraversy on my page as the data is gathered. i have. not added the argument of periheilion problem yet but it looks like 241.7 is. not sept 9th.. maybe sept 4 or 5. the other matters are 'reported' here http:// the ubie . com / is-it . htm -- 72.94.230.198 (talk) 21:37, 30 November 2017 (UTC)

To properly calculate the time/date of perihelion passage you must integrate the orbit backwards. Using JPL Horizons (Soln.date: 2017-Nov-21_20:25:17) I get:

2017-Sep-09 11:47 0.25532707718556 -0.0021052 87.41886 87.41886 31338.2180 0.0234323

Which, in English, is 2017-Sep-09 11:47 UT, 0.25532707718556AU ±31338km from the Sun, going 87.4 ±0.02 km/s.

The GENERIC solution by the JPL SBDB is only a best-fit to the curve (trajectory) at epoch it is defined at. Currently JPL is defining the orbit at epoch 2017-Oct-31. -- Kheider (talk) 22:05, 30 November 2017 (UTC)

US or British English

Time again for that age-old question: which variety of English? I see both. I used US, noted a GB article.User-duck (talk) 23:15, 26 November 2017 (UTC)

With proper deference to titles and quotes.User-duck (talk) 22:06, 30 November 2017 (UTC)

Asteroidal nature: Damocloids

The article currently states: "The lack of a coma indicates that it must have formed within the frost line of the stellar system of origin or have been in the inner region of that stellar system long enough for all ice to sublime, as may be the case with damocloids. Analysis of its spectrum indicates that the latter is likely true".[39][40]

After looking at the link damocloids, I realize the term means inactive comets (ran out of volatiles). I think that was the older (earliest) hypothesis, before they realized it is an asteroid. Since there seems to be reason to think it is instead a dense metallic rock asteroid, we should change the text on that entry. Your thoughts? BatteryIncluded (talk) 23:12, 30 November 2017 (UTC)

I have not checked the latest references or even the references used. But I think you are correct. I was waiting for the table debate to settle down. -- Kheider (talk) 23:55, 30 November 2017 (UTC)

I have changed it to read, "It is difficult to say which scenario is more likely due to the chaotic nature of small body dynamics." (Ye2017) -- Kheider (talk) 13:46, 1 December 2017 (UTC)

How close did it get to Earth?

How close did it get to Earth and what was its speed (relative to Earth) then? What would have been the consequences if it hit the Earth, whether sideways or (probably worse) head on?

From http://www.sciencemag.org/news/2017/11/updated-first-time-astronomers-are-tracking-distant-visitor-streaking-through-our-solar

On 14 October, it made its closest pass by Earth, at 60 times the distance to the moon.

At Oumuamua's closest approach to Earth it was 0.16163 AU (24,180,000 km; 15,024,000 mi) ±6000km away traveling 60.2 km/s with respect to Earth. Given the angles involved it is not moving much faster than typical Oort cloud objects with respect to the Earth. At 2017-Oct-14 17:51 UT, Earth was orbiting the Sun at 29.87 km/s and Oumuamua was traveling 47.89 km/s with respect to the Sun. So by adding those two speeds you could theorize a perfect head-on at 78 km/s. -- Kheider (talk) 18:57, 1 December 2017 (UTC)