Rattling The Beads
by Stephen Saber
May 2006 offered the possible sighting of a Lunar crescent aged less than 24 hours. While I've spotted dozens of younger/very old slivers, the cooperative weather and clean horizon enticed me to make the still-challenging effort.
My mounted 15x63 binoculars first captured our moon aged 20h10m.
Mercury, shining 3° away, may as well been an arrow pointing to it.
Fifteen minutes deeper into twilight I could just glimpse the young moon naked-eye.
As the sky darkened the binoculars also revealed curiously familiar staggered brightness peaks along the setting limb. On this occasion, the first thing I thought of was a more subtle, but unmistakable resemblence to the 'string-of-pearls' effect seen near second and third contacts during a total solar eclipse.
Swinging my 90mm Mak on the sliver at low-power showed the same phenomenon along with an associated low-altitude scintillation.
Very cool.
After my report of this observation, fellow astronomers Curt Renz and Carol Lakomiak nominated the term 'Saber's Beads' to describe the phenomenon which, by August, had caught fire and grabbed the attention of the folks at Astronomy magazine ('Targets Not To Miss', Sept 06).
So how had this obvious and beautiful phase gone unmentioned for so long?
I see at least three possibilities; timing, desire, and recognition.
Virtual Moon Atlas software simulations show the best aesthetic window to be 18-22 hours on either side of New Moon (libration will also vary the Beads' design). How many clear shots at this exact window does one get over, say, 5 years? Not many.
Also, veterans in search of record/near-record thin crescents are often waiting for the challenge of something in the 10-16 hour range to test their skills (as mentioned, I even almost passed on May's relatively 'old' sliver).
In addition, except for the celestial players involved, witnessing an eclipse and hunting a Lunar sliver are very different endeavors. The mindset during the separate events may simply preclude immediate recognition of the unexpected resemblance.
While the solar eclipse counterpart is initiated by direct sunlight seen through our moon's valleys, Saber's Beads are first detected by the early and late angular illumination of the mountainous regions.
In any case, it feels good to give Lunar observers and imagers something new, challenging, and interesting to watch for.
It's also somewhat overwhelming to have your own Lunar phase.
Now everytime I see our moon I just shake my head and smile.
Happy hunting, and enjoy!
Stephen Saber is an Astronomical League Master Observer and author of the 'Starhoppers Guide to the Herschel 400'.
He curses the clouds from his home in Rock Island, Illinois.
(reprinted from the A.L. Reflector, Dec '06)
Saber Does The Stars At:
http://www.astronomyblogs.com/member/saberscorpx/
Rattling The Beads
to IIS.
