Talk:52246 Donaldjohanson
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 | 52246 Donaldjohanson is currently a Physics and astronomy good article nominee. Nominated by Nrco0e (talk • contribs) at 21:40, 28 July 2026 (UTC) This article is ready to be reviewed in accordance with the good article criteria. Any editor who has not nominated or contributed significantly to this article may review the article and decide if it should be listed as a good article. To start the review process, click start review and then save the page. See the instructions. |
 | 52246 Donaldjohanson (final version) received a peer review by Wikipedia editors, which was archived on 2 August 2026. It may contain ideas you can use to improve this article. |
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Formation
There has been a lot of articles/pages about the formation of 52246 Donaldjohanson, So I am thinking that we make a “Formation and evolution” Content or part (I don’t know what it’s specifically called) Fred1000000000 (talk) 13:02, 3 March 2026 (UTC)
Peer review
52246 Donaldjohanson
 | This peer review discussion is closed. |
I've listed this article for peer review because this is a pretty big article (50k bytes) that I've written. I don't have much energy to reread the entire thing to search for grammar and sourcing issues. I'd like to bring it up to good article status and (and possibly up to featured article status afterward), but I want to make sure I've cleared out any hidden issues before I decide to nominate this for GA.
Thanks, Nrco0e (talk • contribs) 23:38, 21 July 2026 (UTC)
Comments by Renerpho
- Hi! Nice article, Nrco0e. Here's not a full review, but you asked me for an informal review, and I guess this is the place to put it? So here are my thoughts. Renerpho (talk) 17:39, 22 July 2026 (UTC)
Lede
- "
52246 Donaldjohanson (abbreviated DJ)
" -- You're not using that abbreviation in the article at all, aside from where you say that this is the common abbreviation. Does the abbreviation belong in the lede (in such a prominent spot) if you're never actually using it in a meaningful way?
- Honestly not sure myself. I see some other people like mentioning alternate names in the lede. But I guess it's fine to remove it. If people complain, then it can be added back, no big deal.
- "
boulders, craters, and ridges
-- When you discuss this further down in the article, you're wikilinking "boulders, craters, and ridges". Why leave out the link to craters in the lede, and why not link boulder at all?
Y Done.
- "
after various archeological sites
" -- There's a difference between archaeology (as linked here) and paleoanthropology (as linked further down in the article when this is discussed again).
- Y Done.
- "
Donaldjohanson tumbles around two axes
" -- However you resolve the issue in the "Rotation" section (see below) should inform what to do about this.
- Y Done.
- "
the YORP effect, which is a gradual torque exerted by sunlight. It is a member of
" -- the YORP effect isn't a member of anything.
- Y Done.
- "
- "
Donaldjohanson and the Erigone family are believed to have formed about 155 million years ago
" -- The Erigone family is believed to have formed about 155 million years ago. Are there any concrete estimates for the timing of the collision between the two "lobes" which subsequently formed Donaldjohanson?
- There's no specific time for the lobes' merging, other than Sky & Telescope saying that the lobes were together for a "long time". Nrco0e (talk • contribs) 23:57, 22 July 2026 (UTC)
- So were my grandparents. That's a bit vague. I think it's better to rephrase:
Donaldjohanson and the Erigone family are believed to have formed within the last 270 million years, in the aftermath of a catastrophic collision between two once-larger asteroids.
This completely avoids the issue. I also changed the ending of the sentence because, like a good marriage, you need two to make a collision. Renerpho (talk) 20:12, 23 July 2026 (UTC)
- "
Discovery
- "
while scanning observations made by the U.K. Schmidt–Caltech Asteroid Survey on 2 March 1981
" -- Is 2 March 1981 the date when he scanned the observations, or the date when the observations were made? Right now it sounds like the former, and I don't think the source supports that. Speaking of which, the source situation here is a bit confusing: M.P.C. 7087 supports the telescope and observer details, but not the date, which appears in M.P.C. 7101. Footnote [f] tries to explain this, but I don't find that explanation satisfying.
- 2 March 1981 is the observation date. I've moved that date to the next sentence.
- MPC 7087 and 7101 are in the same document. MPC 7087 is the "header info" or "context" behind the observations tabulated in 7101. I've clarified this in the footnote. Let me know if it still isn't clear.
- "
In February 1999, Arno Gnädig reported that 1998 YF26 was the same object as Donaldjohanson
" -- That's an anachronism, since Donaldjohanson hadn't been named yet. What Gnädig reported was that 1998 YF26 was the same object as 1981 EQ5.
- Y Done.
- "
Naming and exploration
- "
Donaldjohanson has the minor planet number (52246), which was given by the MPC on 16 February 2003
" -- Why put the number in brackets? There is no reason to do so here (compare Talk:Provisional designation in astronomy#Numbered provisional designations). "Donaldjohanson has the minor planet number 52246" works perfectly fine.
- Y Done.
- "
The name of Donaldjohanson uses a concatenated form of its namesake because the International Astronomical Union requires this format for asteroids named after people
" -- Simpler: "For the asteroid, Donald Johanson's first and last names were concatenated to conform with the International Astronomical Union's naming rules." If you're looking for a place to wikilink List of minor planets named after people then I don't think this is a good place to do it; maybe add a "See also: List of minor planets named after people" to the top of the section?
- Y Done.
- "
The asteroid's name is abbreviated as "DJ".
" -- The asteroid's name is commonly abbreviated as "DJ". Otherwise this sounds as if that's part of the IAU's shenanigans, which it is not.
- Y Done.
- "
nearly three months after NASA's selection of the Lucy mission concept
" -- selection for what? You could wikilink selected here, or spell it out.
- Y Done.
- "
- "
Astronomers had initially speculated that Donaldjohanson might be a binary asteroid
" -- "Initially" isn't quite right. Why would they speculate that before collecting any meaningful data? In truth, those speculations happened at one point, but not "initially".
- Removed the "initially". Should it be mentioned somewhere that the binary speculation no longer holds true?
- Lucy's images disproved the binary suspicions. I recall a source mentioning that, but I'll have to dig it up and see if that's the case... Nrco0e (talk • contribs) 21:24, 22 July 2026 (UTC)
- Great. If you can confirm this, I'd write something like:
Some astronomer(s) [probably good to name them -- who wrote that Hubble proposal? Were they the first?] speculated that Donaldjohanson might be a binary asteroid.[source] This was disproved when Lucy flew by the asteroid.[source]
Renerpho (talk) 21:31, 22 July 2026 (UTC)- @Renerpho: I can't find a source explicitly saying the binary hypothesis was disproven. Some scientists had also speculated that DJ might be contact binary, and discussing the binary vs. contact binary pre-flyby speculations in the article sounds like too much of a detour. Saying that they simply knew it must be elongated is enough. So I'm removing the binary mention. Nrco0e (talk • contribs) 03:34, 23 July 2026 (UTC)
- Great. If you can confirm this, I'd write something like:
- "
- "
first images of Donaldjohanson at a distance of
" -- "from a distance of"
- Y Done.
- "
Over the two months before its encounter
" -- Maybe: "Over the two months leading up to the encounter"
- Y Done.
- "
photographed the asteroid at resolutions up to
" -- "at resolutions of up to"
- Y Done.
- "
in order to avoid pointing its instruments toward the Sun
" -- The concern wasn't that they would point directly at the Sun, but so close to it that stray light might enter the camera and cause damage. Change to "avoid pointing its instruments too close to the Sun".
- Y Done.
- "
Orbit
- "
Donaldjohanson shares a similar orbit as the large asteroid 163 Erigone, which makes it a member of the Erigone family
" -- "Shares ... as" is a bit strange. I'd write: "Donaldjohanson's orbit is similar to that of the large asteroid 163 Erigone, and it has been identified as a member of the Erigone family". There are considerations beyond a similar orbit when it comes to assigning an asteroid to a family; see Interloper (asteroid). The source that's cited for the following point deals with that, looking at the possibility that Donaldjohanson and concluding that this is unlikely.
- Y Done.
- "
Donaldjohanson's orbit is not influenced by any mean-motion orbital resonance with another planet
" -- I don't think the reference supports that claim. It says that "no strongly chaotic mean motion resonance crosses the Erigone family zone", but that "a few smaller resonances interact with the family" (p.3, my emphasis). It also discusses secular resonances, but notes that DJ isn't affected by those and "avoids interaction with any meaningfully strong mean motion resonance" (p.12). The secular resonances may not be worth mentioning, but "meaningfully strong" is an important qualifier.
- Okay... would
Like the majority of Erigone family members, Donaldjohanson's orbit is not influenced by any meaningfully strong orbital resonance with another planet.
work? I've removed the "mean-motion" adjective so that secular resonances are included.
- Okay... would
- "
which would bring it close enough to Mars to weakly influence the asteroid's orbit
" -- Maybe "close enough to Mars for it to weakly influence" is better? The emphasis here is on Mars possibly having an effect.
- Not done. That wording feels awkward IMO. In
which would bring it close enough to Mars for it to weakly influence
, "it" first refers to DJ, and then Mars.
- Not done. That wording feels awkward IMO. In
- "
which pushes the asteroid away from the Sun if it rotates in the same direction as its orbit
" -- And it does, right? Its prograde rotation is discussed in the "Rotation" section. Could you add a pointer, like "if it rotates in the same direction as its orbit (see section Rotation)", or something to that effect?
- Y Done.
- "
Geology
- "
The asteroid has overall dimensions of ...
" -- You could wikilink dimensions (astronomy) here.
- Y Done.
- "
It is estimated to have a mass
" -- I would emphasize more that its mass has not been measured directly.
- I reworded the sentence to
Its mass has not been measured directly, but it is calculated to have a mass of 7×1013 kg, assuming it has a density of 1.2 g/cm3 similar to those of carbonaceous asteroids Bennu and Ryugu.
But I feel like the sentence is too long and I'm having a bit of trouble trying to come up with a better way of phrasing it.
- How about splitting it?
Its mass has not been measured directly. It is estimated to have a mass of 7×1013 kg, assuming a density of 1.2 g/cm3 similar to that of carbonaceous asteroids Bennu and Ryugu.
Renerpho (talk) 21:10, 22 July 2026 (UTC).
- How about splitting it?
- I reworded the sentence to
- "
The International Astronomical Union (IAU) and Lucy team
" -- "and the Lucy team".
- Y Done.
- "
have given formal names to several geological features
" -- "formal names" could link to Planetary nomenclature.
- Y Done.
- "
in honor of significant paleoanthropological sites and hominin discoveries
" -- I think it's a good idea to wikilink both Paleoanthropology and List of human evolution fossils, even if the latter is already linked in the lede.
- Y Done.
- "
Lobes
- "
after the Afar Triangle in Ethiopia, while the larger lobe is named Olduvai Lobus, after Olduvai Gorge in Tanzania
" -- why are you wikilinking Tanzania, but not Ethiopia?
- Y Done.
- Is there some style guide for when to italicize names of geological features? Throughout the article, you seem to be inconsistent, sometimes italicizing the names of features like Afar Lobus, and sometimes not. Sometimes you are italicizing the first appearance of a name; sometimes you're not (e.g. Boxgrove Saxum).
- Honestly, I didn't know whether newly-introduced geological feature names should be italicized or quoted. I had a quick look at the MOS and other planet articles and they seem to leave place names unitalicized. So I'll just remove the italics.
- "
Because Olduvai Lobus is larger, the entire asteroid's center of mass is shifted toward it.
" -- More precise (and closer to the source): "the entire asteroid's center of mass lies inside it".
- Y Done.
- "
- "
Both lobes are heavily covered with impact craters, to the point that any new crater would destroy older ones.
" -- Not only would it destroy older ones, but it would, on average, destroy one older crater, keeping the total count roughly the same. The source is imprecise here: This is true for craters larger than 0.4 km (, p. 1288, quote: "Craters larger than D = 0.4 km follow a power law with a slope of approximately −2 (Fig. 4A), consistent with crater equilibrium (crater density nearly constant with time)"). It is not true for smaller craters ("a lower density than expected for equilibrium"). You discuss the reason for that a few sentences later (small craters were preferentially erased), but still, the thing about the crater count being in equilibrium only applies to the larger ones.
- So... just say
to the point that any new large crater would destroy older ones
? Nrco0e (talk • contribs) 00:28, 23 July 2026 (UTC)
- Hmm... I'm not sure. That sounds trivial (large boom makes a mess, duh), even though it's not. Renerpho (talk) 19:14, 23 July 2026 (UTC)
- @Nrco0e: Maybe something closer to the original source?
Both lobes are heavily covered with impact craters. The largest known crater on Afar Lobus has a diameter between 0.8 and 0.9 km (0.50 and 0.56 mi), whereas Olduvai Lobus's largest known crater has a diameter between 2 and 3 km (1.2 and 1.9 mi).[1]: Fig4 The number density of craters larger than 400 m (1,300 ft) appears to have reached a steady state where it remains nearly constant over time.[1][footnote] In contrast, craters with diameters smaller than 400 m appear scarcer on both lobes. Crater counts indicate that small craters were erased within the last 40 million years.[1] The Lucy team proposed that they were erased by the flow of loose material, when a large impact event triggered seismic shaking across Donaldjohanson's surface.[1][2]
[footnote]: Any impact would, on average, destroy one older crater and leave a new one.[3]
- And I would put
The asteroid's surface is estimated to have a cohesive strength of up to 40,000 pascals, probably much higher than those of loosely-bound rubble pile asteroids like Bennu and Ryugu (cohesive strengths <100 Pa).[1]: 1288
in the "Geology" section, after the sentence with the mass estimate. Renerpho (talk) 19:35, 23 July 2026 (UTC)
- So... just say
- "
- "
a cohesive strength of up to 4,000 pascals
" --is 40,000.
- Y Done.
- "
higher than those of loosely-bound rubble pile asteroids like Bennu and Ryugu
" -- The logic here is a bit subtle: If Donaldjohanson had a cohesive strength as low as Bennu or Ryugu, that would put an upper limit of ~1 million year on the age of its surface, which the authors believe is too short for known erasing mechanisms.
- "
Neck
- "
which divides the neck into Hadar Regio at Afar Lobus and Minatogawa Regio at Olduvai Lobus (named after Hadar, Ethiopia and the Minatogawa Man, respectively). Of these two regions, Hadar Regio constitutes a larger portion of Windover Collum.
" -- I think this can be said in fewer words: "which divides the neck into a larger Hadar Regio at Afar Lobus and a smaller Minatogawa Regio at Olduvai Lobus (named after Hadar, Ethiopia and the Minatogawa Man, respectively)."
- Y Done.
- "
This is evident from the smooth terrain seen between Afar Lobus and Windover Collum (Hadar Regio)
" -- Why not write "This is evident from the smooth terrain seen in Hadar Regio"?
- Y Done.
- "
The side of Luzia Dorsum facing Afar Lobus has a shallow slope under 10°
" -- I think "shallow slope of less than 10°" is better.
- Y Done.
- "
These characteristics of Windover Collum indicate that it has undergone relatively recent resurfacing less than 20 million years ago
" -- "indicate" repeats a word from the previous sentence. I would rephrase: "These characteristics of Windover Collum suggest that it has undergone resurfacing relatively recently, less than 20 million years ago".
- Y Done.
- "
Other features
- "
All three features have diameters of at least 10 m
" -- Is there a source that actually says so? The current source gives diameters of 0.01 km for all three, but accounting for rounding, that could mean as little as 5 m. Is there some concrete reason why a size of more than 10 m is important? Otherwise I'd strike the whole sentence.
- Gotta admit, I'm somewhat skeptical of the diameters listed on the WGPSN's site since I've seen before that that can be somewhat inaccurate and do not specify how they were measured. And 10 meter diameter sounds too small to sound true IMO. Would it be fine removing that sentence then? The next sentence says they are the smallest identifiable features which gives an idea of their size. Nrco0e (talk • contribs) 23:04, 22 July 2026 (UTC)
- "
- "
diameters 80 and 100 m, respectively
" -- no conversion to feet this time?
- Y Done. Since I expressed doubts on the accuracy of the WGPSN's diameter figures above, would it be worth keeping these diameter estimates here?
- Have you got any concrete evidence that those numbers are wrong? Renerpho (talk) 22:52, 22 July 2026 (UTC)
- "
All named boulders and craters are located on Olduvai Lobus
" -- The source provides a map that seems to support that conclusion, but the text doesn't seem to actually say so. Is there a source that shows that this fact is relevant?
- Relevant? Is that an issue?
- Nah, I guess WP:ORMEDIA covers it, so it's fine. Renerpho (talk) 19:11, 23 July 2026 (UTC)
- "
Rotation
- "
it wobbles back and forth around two axes
" -- I think I know what you want to say, but the word "axes" here might lead to confusion. I'd just write "it wobbles chaotically", which is then explained in the next sentence. Maybe it's worth adding that its orientation in space never exactly repeats,(, suppl. mat., p.5) something I found quite interesting.
- "
- "
ground-based telescopes detected periodic brightness variations ranging 1 magnitude
" -- This comes with two sources, one of which just repeats and cites the other; so I think you can remove that one. The source says "~1 magnitude", and I'd keep that: "ranging approximately 1 magnitude".
- Y Done.
- "
The asteroid's slow, tumbling prograde rotation is an expected outcome of the YORP effect
" -- I don't think the YORP effect favors prograde rotation, does it? So I'd strike "prograde" from that sentence. The important part here, I think, is that it's slow and tumbling.
- Y Done.
- "
During this time, the asteroid's centrifugal acceleration
" -- More precisely: The centrifugal acceleration on the asteroid's surface.
- Y Done.
- "
If left undisturbed by YORP or impacts, the asteroid is predicted to continue tumbling for about 20 billion years before it stabilizes to a fixed rotation axis
" -- If left undisturbed "by outside forces like YORP or impacts". This is not a prediction that the Solar System will be around 20 billion years from now.
- Y Done.
- "
notes that their timeline of Donaldjohanson's rotation may not be fully accurate
" -- Isn't it enough to write "notes that that timeline may not be fully accurate"?
- "
Surface composition
- "
which indicate that they had been altered
" -- "have been altered".
- Y Done.
- "
as iron in clay tends to
" -- You previously introduced the term "clays", and I'd stick with that: "as iron in clays tends to".
- Y Done.
- "
- "
In visible light, the asteroid has a geometric albedo of about 10%.
" -- This is based on pre-flyby measurements from 2011 by the WISE spacecraft, assuming a diameter of about 3.9 km, right? If I recall correctly, Donaldjohanson's true size was something of a surprise. Consequently, the true albedo should be somewhat lower? Are there any more recent estimates/sources? Renerpho (talk) 19:56, 23 July 2026 (UTC)
- @Renerpho: no recent estimate or discussion about DJ's albedo, unfortunately. Nrco0e (talk • contribs) 20:18, 23 July 2026 (UTC)
- That's a problem. In that case, I'd attribute the albedo, spell out the underlying assumption, and add a footnote. I'd also get rid of the JPL reference, instead citing the WISE paper directly. Maybe something like this:
There are no recent estimates of the asteroid's geometric albedo. Infrared observations by the WISE spacecraft in 2011 found a diameter of about 3.9 kilometres (2.4 mi), corresponding to a geometric albedo in visible light of about 10%.[4][5][footnote]
[footnote]: The Lucy spacecraft found that the asteroid is actually somewhat larger than originally thought.[citation needed] A larger size generally corresponds to a lower albedo.[citation needed] The wrong diameter found by WISE may be a result of the asteroid's slow rotation and highly elongated shape.[citation needed]
- I don't think that crosses the line into original research (calculating its "true" albedo yourself surely would).
- If I remember correctly, I recently had a conversation with Exoplanetaryscience where they mentioned a possible source for the "wrong diameter found by WISE is a result of the asteroid's slow rotation and highly elongated shape" part (not for Donaldjohanson in particular, but for asteroids like it in general). I have no idea what that source was. Renerpho (talk) 20:44, 23 July 2026 (UTC)
- So the answer is a bit complicated and requires a bit of explaining. The albedo value of 0.103 cited in the article comes from the very initial NEOWISE asteroid characteristics paper (Mainzer et al 2011) which analyzes two different properties in parallel: pV and pIR. pV is derived for all detected asteroids, and is based on comparing the thermal luminosity in WISE bands with the JPL SBDB H value. Since the H value is more-or-less a rotationally averaged long term luminosity, then pV is prone to biasing if WISE systematically observed a highly elongated asteroid at a particularly large or small perspective. However, pIR is purely based on WISE's data: it compares the luminosity in the W1/W2 filters (shorter wavelength, mostly non-thermal) with its luminosity in W3/w4 (longer wavelength, mostly thermal) to derive the albedo in the infrared region. Since this is comparing observations taken at the exact same time, it is not prone to this rotational biasing: even if it's only observing a specific biased perspective of an asteroid, it will still accurately record the albedo of that hemisphere, whatever it is.
- With that said, the 0.103 value quoted for Donaldjohanson is the pV. Although it might initially seem paradoxical that they give an even higher infrared albedo of 0.155 (given that the pV is already estimating the asteroid to be smaller than in reality), the infrared albedo is usually a good deal higher than in visible light and can't be directly used to calculate diameter without knowing the infrared absolute magnitude. There is another systematic issue that has come up here though- this older version was relying on older absolute magnitude estimates as well, and for Donaldjohanson recorded H=15.2, much brighter than its modern H=15.61. In addition to overestimating the pV, its visible luminosity was also overestimated, leading to a partial cancelling out of this systematic issue. Indeed if you model H=15.2 p=0.103 you get a diameter of 3.78 km (close to their reported 3.90 km diameter, likely revised upwards taking into the infrared albedo). While it isn't trivial to estimate the size using the modern H=15.61 since changing the H would also change their calculated pV, suffice to say it would be even smaller than this. BTW - you can find mention of this problem in the paper itself; towards the end of page 4. The full quote is a bit verbose to include here but generally they mention that high-amplitude rotators' diameters should be taken with a grain of salt.
- This doesn't have to be where we give up and either defer to OR or including knowingly bad data though. There are more recent, objectively higher quality estimates of Donaldjohanson's diameter and albedo (even if we didn't have the hindsight of the flyby). Masiero et al published papers in 2020 and 2021 using two new datasets from NEOWISE (years 4-5 and 6-7 respectively) which recorded albedos of 0.040 ± 0.019 and 0.045 ± 0.034 respectively, with modeled H's closer to the current value (H=15.45). Indeed both of their diameter estimates, 5.5 ± 1.2 and 5.1 ± 1.2 km, are much closer to the now-known value. Not only is the H estimate more modern/accurate, but they each use roughly 4x as much data as the 2011 paper, being able to rely on four separate observations at quadrature instead of a single one-night visit in March 2010. I have no idea why JPL and the LCDB don't update with such things, but I think the "official" values quoted for them should be taken as thoroughly deprecated and ignored in favor of this newer stuff- no OR or synthesis required. exoplanetaryscience (talk) 23:08, 23 July 2026 (UTC)
- Thanks a lot! @Nrco0e: With that, I think you can deprecate the JPL value. Just quote the latter number ({{val|0.045|0.034}}), in both the article and the infobox (the 2021 paper supersedes the 2020 one). Renerpho (talk) 23:20, 23 July 2026 (UTC)
- Thanks y'all! Do I cite both Masiero 2020 and 2021 for H=15.45? Nrco0e (talk • contribs) 23:29, 23 July 2026 (UTC)
- No need to cite the 2020 paper at all. The 2021 paper is the more recent one, using the same data (plus more from years 6+7). Renerpho (talk) 23:33, 23 July 2026 (UTC)
- Small correction- the two papers are complementary. the 2021 paper *only* uses years 6-7, and the 2020 paper *only* uses years 4-5 to my knowledge. exoplanetaryscience (talk) 23:34, 23 July 2026 (UTC)
- I've replaced the albedo with the 2021 value. Is the footnote still needed? Nrco0e (talk • contribs) 23:50, 23 July 2026 (UTC)
- No need to cite the 2020 paper at all. The 2021 paper is the more recent one, using the same data (plus more from years 6+7). Renerpho (talk) 23:33, 23 July 2026 (UTC)
- Thanks y'all! Do I cite both Masiero 2020 and 2021 for H=15.45? Nrco0e (talk • contribs) 23:29, 23 July 2026 (UTC)
- @Exoplanetaryscience: You write "I have no idea why JPL and the LCDB don't update with such things" -- I don't know why JPL doesn't update, but the LCDB does. The most recent version of the LCDB (2023) cites both the papers you mention (, look up the asteroid). It also gives an albedo of 0.057 for the asteroid, probably some kind of average of all the values found in the literature. Renerpho (talk) 23:32, 23 July 2026 (UTC)
- Thanks a lot! @Nrco0e: With that, I think you can deprecate the JPL value. Just quote the latter number ({{val|0.045|0.034}}), in both the article and the infobox (the 2021 paper supersedes the 2020 one). Renerpho (talk) 23:20, 23 July 2026 (UTC)
- @Renerpho: no recent estimate or discussion about DJ's albedo, unfortunately. Nrco0e (talk • contribs) 20:18, 23 July 2026 (UTC)
- "
Search for moons and cometary activity
- "
found no signs of cometary activity or ...
" -- shouldn't this link to the active asteroid article instead, like so: "found no signs of cometary activity or ..."?
- "
Origin
- "
it is estimated that the Erigone family formed between 115 and 225 million years ago, most likely around 155 million years ago. This makes the Erigone family relatively young compared to other asteroid families
" -- Those two sentences come with two different sources, and , and the parts you quote contradict each other. Since both papers share a main author and were both published very recently, I don't think this is a real disagreement. Nonetheless, the two papers give different ages for the family, quote: "the Erigone collisional family, which has been estimated to have formed between about 130 and 270 Myr ago", vs. "the Erigone asteroid family, which formed 115 million to 225 million years ago". I would rephrase the first sentence, maybe like this: "it is estimated that the Erigone family formed within the last 270 million years, most likely around 155 million years ago." Add the relevant reference after "270 million years". The rest can be kept.
- Y Done.
- "
The Erigone family is believed to have formed from the destruction of an 80 km (50 mi)-diameter parent asteroid to a collision with a 20 km (12 mi)-diameter asteroid
" -- either "parent asteroid that collided with" or "parent asteroid due to a collision with".
- Y Done.
- "
Notes
- "
can be translated into sphere with radius
" -- "is equivalent to a sphere of radius" seems better. In any case, an "a" is missing before "sphere".
- Y Done.
- "
explanation of yaw, pitch, roll
" -- "explanation of yaw, pitch, and roll", or "explanation of yaw, pitch and roll" (depending on whether you're using sequential comma).
- "
- "
5° is the axial tilt (obliquity) of Donaldjohanson's angular momentum vector with respect to its orbital plane
" -- The angular momentum vector remains constant, right? I think that's worth mentioning here. You're writing "which accounts for precession" in the following note, but reminding folks what that means -- that angular momentum is conserved -- is never a bad thing...
- Doesn't the angular momentum vector direction change in precession? The source doesn't mention whether DJ's angular momentum vector changes, but I don't want to make any assumptions. So for now, I've removed the "accounts for precession" part. Nrco0e (talk • contribs) 22:46, 22 July 2026 (UTC)
- "
- "
However, a later paper by the Lucy team contradicts this
" -- "contradicted" (past tense), in accordance with the first part of the sentence.
- Y Done.
- "
Comments by Praemonitus
- Comments: Overall the article looks to be in fine shape and the writing is of good quality. I do have a couple of points:
The article says that, "Donaldjohanson shares a similar orbit as the large asteroid 163 Erigone, which makes it a member of the Erigone family." My understanding is it has to share an orbit and similar physical properties, or it may just be an interloper.
- @Praemonitus: I believe I have addressed this in response to Renerpho's comments. Let me know if the change suffices. Nrco0e (talk • contribs) 23:57, 22 July 2026 (UTC)
I suggest the 'Surface composition' section make it clear that both of the merged components show an identical composition (being from the same progenitor body), or else point out any compositional differences.
- Marchi et al. (2026) use a globally-averaged spectrum for DJ's entire surface, but doesn't elaborate on differences between the two lobes. I can't find any other source that discusses compositional and albedo differences between the lobes, nor do they explicitly state that they share the same composition. Perhaps I can say
meaning its entire surface is dark and made of carbonaceous chondrite-like minerals
instead ofmeaning it has a dark surface made of carbonaceous chondrite-like minerals
? Nrco0e (talk • contribs) 23:57, 22 July 2026 (UTC)
- Okay, it doesn't sound like you can do much about that. Thanks. Praemonitus (talk) 13:09, 23 July 2026 (UTC)
- Marchi et al. (2026) use a globally-averaged spectrum for DJ's entire surface, but doesn't elaborate on differences between the two lobes. I can't find any other source that discusses compositional and albedo differences between the lobes, nor do they explicitly state that they share the same composition. Perhaps I can say
- Thanks. Praemonitus (talk) 18:21, 22 July 2026 (UTC)
Comments by Nrco0e
Wow! Thank you so much @Renerpho and Praemonitus: for the quick feedback! I'll try incrementally responding to each of your points.
I also have a question for both of you—in the article, should it be spelled "U.K." or "UK"? The links for U.K. Schmidt–Caltech Asteroid Survey and UK Schmidt Telescope use different spellings and I prefer that they be consistent. Nrco0e (talk • contribs) 20:46, 22 July 2026 (UTC)
- @Nrco0e: If you have comments/questions about any of my points above, just tag me here, or directly up there in my list, if that works better for you.
- The source spells it "U.K. SCHMIDT TELESCOPE" but "U. K.-CALTECH ASTEROID SURVEY". The two aren't perfectly consistent (U.K. vs. U. K. with an extra space), but both use the periods, and I'd go with that. I think U.K. Schmidt Telescope ought to be a redirect. Renerpho (talk) 20:59, 22 July 2026 (UTC)
Final comments
@Renerpho: Anything more to say, especially the footnote about NEOWISE albedo which I still have yet to add? Should I nominate this for GA now? Nrco0e (talk • contribs) 22:47, 26 July 2026 (UTC)
- @Nrco0e: I'll try to give it a read again tomorrow (it is 1 a.m. and I'm about to sign off), and to have a look at the albedo situation again. If I haven't commented again within 24 hours, go ahead as you see fit. Renerpho (talk) 23:09, 26 July 2026 (UTC)
- Masiero, J. R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2). arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.
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