<p>From Wikipedia's <a href="https://en.wikipedia.org/wiki/Baily%27s_beads" rel="nofollow noreferrer">Baily's beads</a>:</p>
<blockquote>
<p>Lunar topography has considerable relief because of the presence of mountains, craters, valleys and other topographical features. The irregularities of the lunar limb profile (the &quot;edge&quot; of the Moon, as seen from a distance) are known accurately from observations of grazing occultations of stars. <strong>Astronomers thus have a fairly good idea which mountains and valleys will cause the beads to appear in advance of the eclipse.</strong> While Baily's beads are seen briefly for a few seconds at the center of the eclipse path, their duration is maximized near the edges of the path of the umbra, lasting around 90 seconds.</p>
</blockquote>
<p>The article asserts without support that &quot;Astronomers thus have a fairly good idea which mountains and valleys will cause the beads to appear...&quot; and I am sure it's absolutely possible considering how well the lunar topography has been mapped and the celestial mechanics and rigid body motions of the relevant bodies have been ephemerized.</p>
<p>But I've never actually seen a bead-attribution, much less a bead-prediction.</p>
<p>So I'd like to ask:</p>
<p><strong>Question:</strong> Has anyone attributed a specific Baily's bead to a specific feature on the Moon? If so, when was this first done?</p>
<p>Please cite or link to specific examples.</p>

CC BY-SA 4.0
2024-04-17T12:31:27.933Z
I think you need to ask when was the first publication of this.  Anyone with a telescope and a clock could have worked it out and left no notes.
eshaya
CC BY-SA 4.0
2024-04-17T13:39:26.137Z
@eshaya answers must be supported by citing authoritative sources, so the requirement for a publication is sort-of implicit here, because this is Stack Exchange.
uhoh
CC BY-SA 4.0
2024-04-17T21:48:00.327Z
Xavier Jubier's simulator maps them all. Such a model only requires a moon model and position data.  Since it hardly provides any scientific value, I doubt much has been written about it.http://xjubier.free.fr/en/site_pages/solar_eclipses/HSE_20230420_pg02_Baily_Beads_Simulation.html
Greg Miller
CC BY-SA 4.0
2024-04-17T22:03:00.740Z
@GregMiller Hey thanks! I'm thinking that when the beads were first explained, it was a big deal, because before then they were not understood at all. However, the explanation was really just a theory, and it needed to be tested and verified. So I'm pretty confident there will be scientific literature at some point. The Moon's libration means that a feature that's on the limb at one point in time will also be turned a little bit toward us at another. So it might even be possible that once good lunar photographic maps (from Earth) became possible, one could match a given bead to a given feature
uhoh
CC BY-SA 4.0
2024-04-17T22:04:43.590Z
@GregMiller in the mean time, I think that already rises to the level of a partial "these days it's easy" answer, which addresses the first part of the question, but not the second part; "If so, when was this first done?"
uhoh
CC BY-SA 4.0
2024-04-17T22:22:52.377Z
I don't know if Chester Watt's work published in 1963 was the first or not. See https://en.m.wikipedia.org/wiki/Lunar_limb His work was used by IOTA to produce grazing occultation predictions,  so it would have been accurate enough for Bailey bead predictions.  Whether it was and whether it was done beforehand still needs to be determined.
JohnHoltz
<observational-astronomy><the-moon><amateur-observing><orbital-mechanics><solar-eclipse>
Has anyone attributed a specific Baily's bead to a specific feature on the Moon? If so, when was this first done?
uhoh
# Has anyone attributed a specific Baily's bead to a specific feature on the Moon? If so, when was this first done?

(Asked by: username_0 on 2024-04-16)

From Wikipedia's [Baily's beads](https://en.wikipedia.org/wiki/Baily%27s_beads):

> Lunar topography has considerable relief because of the presence of mountains, craters, valleys and other topographical features. The irregularities of the lunar limb profile (the "edge" of the Moon, as seen from a distance) are known accurately from observations of grazing occultations of stars. **Astronomers thus have a fairly good idea which mountains and valleys will cause the beads to appear in advance of the eclipse.** While Baily's beads are seen briefly for a few seconds at the center of the eclipse path, their duration is maximized near the edges of the path of the umbra, lasting around 90 seconds.

The article asserts without support that "Astronomers thus have a fairly good idea which mountains and valleys will cause the beads to appear..." and I am sure it's absolutely possible considering how well the lunar topography has been mapped and the celestial mechanics and rigid body motions of the relevant bodies have been ephemerized.

But I've never actually seen a bead-attribution, much less a bead-prediction.

So I'd like to ask:

**Question:** Has anyone attributed a specific Baily's bead to a specific feature on the Moon? If so, when was this first done?

Please cite or link to specific examples.

**Tags:** observational-astronomy, the-moon, amateur-observing, orbital-mechanics, solar-eclipse

> **Comments:**
> **username_1**: I think you need to ask when was the first publication of this.  Anyone with a telescope and a clock could have worked it out and left no notes.  
> **username_0**: @username_1 answers must be supported by citing authoritative sources, so the requirement for a publication is sort-of implicit here, because this is Stack Exchange.  
> **username_2**: Xavier Jubier's simulator maps them all. Such a model only requires a moon model and position data.  Since it hardly provides any scientific value, I doubt much has been written about it.http://xjubier.free.fr/en/site_pages/solar_eclipses/HSE_20230420_pg02_Baily_Beads_Simulation.html  
> **username_0**: @username_2 Hey thanks! I'm thinking that when the beads were first explained, it was a big deal, because before then they were not understood at all. However, the explanation was really just a theory, and it needed to be tested and verified. So I'm pretty confident there will be scientific literature at some point. The Moon's libration means that a feature that's on the limb at one point in time will also be turned a little bit toward us at another. So it might even be possible that once good lunar photographic maps (from Earth) became possible, one could match a given bead to a given feature  
> **username_0**: @username_2 in the mean time, I think that already rises to the level of a partial "these days it's easy" answer, which addresses the first part of the question, but not the second part; "If so, when was this first done?"  
> **username_3**: I don't know if Chester Watt's work published in 1963 was the first or not. See https://en.m.wikipedia.org/wiki/Lunar_limb His work was used by IOTA to produce grazing occultation predictions,  so it would have been accurate enough for Bailey bead predictions.  Whether it was and whether it was done beforehand still needs to be determined.  

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