by Jason Prochaska
In May 2006 American astronomer and veteran crescent hunter Stephen Saber was first to note a striking visual similarity between certain very thin lunar crescents and solar eclipse contacts. What made this particular crescent stand out to him was a rare combination of the limb’s staggered profile also appearing far enough away from the sun to be captured in a dark sky (well into nautical twilight) before moonset. Too old, and the crescent appears as a continuous arc. Too young, and the crescent cannot reach sufficient elongation from our sun to be observed in a dark sky. With a favorable libration this creates a nominal window of 18-28 hours before or after New Moon to observe, photograph, or image the phenomenon. As the crescent thickens, the beads become larger with fewer gaps inbetween.
Along with short exposures, an equally important element to capturing Saber’s beads is intent. One must go after the effect with the mindset of producing the eclipse contact resemblance, or, during a total eclipse, capturing the infant crescent similarity. Adding spikes to the staggered brightness peaks also enhances the aesthetics. Finally, following these remarkably thin lunar crescents into low-altitude turbulence near the horizon creates a powerful dynamic to the ‘string-of-pearls’ mirrored lunar aspects.
More common and easier to detect are Saber’s inherited and upgraded precursor beads seen at the horns of older waxing and waning crescents which can be observed to appear then combine with (or detach then fade from) the contiguous crescent rim over hours or even minutes of viewing.
Slowly defocusing these tip beads produces the smokey, overlapping links of “Saber’s chain”. As Stephen mentions, “the more beads, the better- like Mardi Gras…”. Indeed, my own impressions have been that of a cosmic thought bubble.
While the viral properties of the internet have since expanded Sabers beads into the world of literature, music, and the transcendental (representing open-mindedness and increased perspective i.e., experiencing a Saber’s beads moment), the visual dusk and dawn apparitions remain a beautiful celestial sight not to be missed.
Outreach Gone Wild: Listen to Saber’s Beads at YouTube
Also see New Moon: Extreme Crescent Visibility
[reprinted with permission/j.prochaska/starwind.net2012]
* * * * *