Swirl

High-Albedo Swirls on the moon's surface

Above image shows a Clementine UVVIS multispectral view of one of the most famous lunar swirls on the Moon, Reiner Gamma (with its northeastern and southwestern extensions in Oceanus Procellarum).
 
 

Description

Swirls are bright, often splashy-looking areas that are typically associated with strong magentic anomalies. Reiner Gamma is the most familiar swirl on the Moon.
 
 

Orbital photographs of swirls, made during the Apollo project

Research: Danny Caes
 
  - The Swirl field' between craters Abul Wafa and Firsov ('2° North/ 115° East) (LAC 65, page 130 in B.Bussey's and P.Spudis's Clementine atlas of the Moon)
 AS10-30-4365 (source: Project Apollo Archive, Kipp Teague).
 
  - The Swirl field between Firsov, Katchalsky, and Viviani (LAC 65, page 130 in B.Bussey's and P.Spudis' Clementine atlas of the Moon)
  Apollo 16 Hasselblad photograph:
 AS16-118-18898
  Apollo 17's Itek-panoramic photographs:
 AS17-P-2079 (Revolution 14, Forward Facing Camera).
 AS17-P-2081 (Revolution 14, Forward Facing Camera).
 AS17-P-2084 (Revolution 14, Aft Facing Camera).
 AS17-P-2086 (Revolution 14, Aft Facing Camera).
 
  - The swirl-field west-northwest of Lobachevskiy (10°30' North/ 110° East)
 AS17-151-23185 is one of Apollo 17's orbital Hasselblad photographs of this swirl field. It was also included on page 30 of the article A Swirl of Moondust by Bridget Mintz Testa (see Bibliography below).
 
  - The swirl west of near-side crater Airy, at the unofficially named Loro Basin
  Apollo 16's Fairchild-metric (mapping) photograph AS16-M-2473 shows this swirl between Albategnius (right) and the central part of the curved horizon.
 
  - Mare Marginis swirl
 
 

Official (and rather short) list of high-albedo swirls on the moon's surface

Name	Lat	Long	Antipode	Area km^2
Airy crater	-18.0	5.7	none	1300
Apollo basin	-25.0	-165.0	Serenitatis	275
Gerasimovich	-22.9	-122.6	Crisium	10,000
Mare Marginis	13.0	84.0	Orientale	50,000
Mare Moscoviense	26.7	144.0	Humorum	35
Reiner Gamma	7.9	-59.0	none	10,000
Van de Graaff / Mare Ingenii	-27.4	172.2	Imbrium	10,000

Additional Information

There are much more swirl-fields and solitary swirls on the moon than those mentioned in the very short list above!
  An investigation of orbital and telescopic photographs by Danny Caes
 
 Swirlette (1° South / 61° West)
  One of those curious little Reiner Gamma type swirls is located at 1° South/ 61° West, between craters Hermann and Lohrmann A (north-northeast of Grimaldi C, south-west of the small craterlet Hermann C). See LPOD Swirlette
  The little Reiner Gamma type swirl near Lohrmann A was also captured by Bob Pilz (see photograph).
  It is also noticeable near the lower right corner of Lunar Orbiter 4 frame 162-h1.
  On chart 49 of the Times Atlas of the Moon it is depicted as an unnamed craterlet.
  On LAC 74 (page 148) of the Clementine Atlas of the Moon, it is depicted as a curly swirl.
  Chart 39 of Antonin Rukl's Atlas of the Moon shows just nothing (only an unnamed north-south oriented wrinkle ridge).
 
 B shaped swirl (7° South / 54° West)
  Another one of those swirls is located at 7° South/ 54° West, at the same location of J.F.J.Schmidt's Melloni, and H.P.Wilkins' Burrell. According to Whitaker, this formation (Burrell) seems to have become less conspicuous during the recent decennia. On Antonin Rukl's Chart 40 it is depicted as a weak difference of albedo-value. The Clementine photograph (LAC 74) shows a distinct swirl-like appearance.
  See also: Lunar Orbiter 4 frame 156-h3 (the B shaped swirl is depicted near the frame's lower right corner, just northwest of the U shaped incomplete crater), and Burrell-Melloni - a curious case of observation
 
 WNW Sirsalis E (7°30' South / 58°30' West)
  Here's another possible candidate, located west-northwest of the incomplete crater Sirsalis E. It is noticeable as a swirl-like appearance on LAC 74 (page 148) of the Clementine Atlas of the Moon.
 
 Mare Tranquillitatis swirl (12°30' North / 20°30' East)
  There's a very weak candidate to the west-northwest of Ross in Mare Tranquillitatis (in the triangle Ross - Ross C - Tacquet C, north of Ross B). This possible swirl is visible on page 120 of the Clementine Atlas of the Moon (LAC 60), and also on several orbital Mapping/Metric frames made during Apollo 15, such as AS15-M-2697.
  See also LROC Act-React Quickmap shortlink http://bit.ly/2mAmyKw
 
 The Schroter swirls
  This is an unofficial name from D.Caes for a possible field of very weak Reiner gamma type swirls east of Schroter (this is the officially unnamed mare-like region between Schroter and Sinus Medii). To see this field of possible swirls, one should take a look at the shadowless WAC albedo-mosaic of the LROC's Act-React Quick Map.
  See also page The Possible Swirl field east of Schroter.
 
 A possible bright and compact swirl on the floor of the unnamed "half crater" southeast of Buisson Y ('0°30' North/ 113°15' East)
  This possible swirl was captured on several orbital Apollo photographs:
  Apollo 10:
  - Orbital Hasselblad photograph AS10-28-4125.
  Apollo 11:
  - Orbital Hasselblad photograph AS11-36-5426 (near the frame's lower left corner).
  Apollo 16:
  - Orbital Hasselblad photographs AS16-113-18281 (near the frame's upper left corner) and AS16-113-18282 (a little bit lower than its "near-the-corner" appearance on the preceding photograph).
  Apollo 16 orbital ITEK-panoramic photographs:
  - Scroll rightward at both Itek-panoramic photographs of Apollo 16's orbital stereo pair AS16-P-4279 (Forward looking) and AS16-P-4284 (Aft looking).
  - Near the left margin of Apollo 16's orbital Itek-panoramic photographs AS16-P-4847 and AS16-P-4849 (both Forward looking), and also AS16-P-4854 (Aft looking).
  Apollo 16's orbital FAIRCHILD-Mapping/Metric photographs:
  - Frame AS16-M-0496 (near the lower left corner), and its preceding frames in REV 25.
  - Frames AS16-M-0626, 0627, 0628, 0629, and 0630.
  Apollo 17:
  - Orbital Hasselblad photographs AS17-150-23083, 23084, 23085, 23086, and 23087 (a series of five frames).
  - Orbital Hasselblad photograph AS17-150-23105 (note the bright formation's hazy appearance, on the Print Resolution JPG, 4.4 MB).
  - Orbital Hasselblad photographs AS17-151-23167 and AS17-151-23170.
  Apollo 17 orbital ITEK-panoramic photographs:
  - AS17-P-2079 (Revolution 14, Forward looking), AS17-P-2084 (Revolution 14, Aft looking).
  Important: at the following two Itek photographs it's necessary to scroll rightward toward the right margin of both frames:
  - AS17-P-2497 (Revolution 28, Forward looking), AS17-P-2502 (Revolution 28, Aft looking).
 
 A possible tiny swirl on the floor of Hero H, a small crater between Hero and Soddy ('0°10' North/ 120°30' East)
  This swirlette (tiny swirl) is noticeable near the lower margin of Clementines photographic version of LAC 65, and also on several orbital Apollo photographs, such as:
  Apollo 10:
  - AS10-29-4204 (captured at centre of frame, the irregular crater near the frame's lower margin is Soddy).
  - AS10-29-4205 (captured near the frame's lower left corner, the central crater is Hero).
  Apollo 16:
  - Apollo 16's panoramic ITEK-camera frames AS16-P-4259, AS16-P-4264, and AS16-P-4266 show close ups of Hero H and its possible swirl (in all three frames it is not necessary to scroll to the right).
  Apollo 17:
  - Apollo 17's panoramic ITEK-camera frames AS17-P-2061 and AS17-P-2066 also show Hero H and its possible swirl (at both frames it is necessary to scroll to the centre).
  - Apollo 17's panoramic ITEK-camera frames AS17-P-2475 and AS17-P-2480 show oblique northward looking views of Hero H and its possible swirl (at both frames it is necessary to scroll all the way toward the right margin!).
 
 The swirl formation at the southwestern part of crater Mobius's floor ('15°30' North/ 100°45' East)
  This curious swirl was captured on Apollo 17's orbital ITEK-panoramic photographs AS17-P-1859, AS17-P-1861, AS17-P-1866, and AS17-P-1868 (scroll all the way toward the right margins of all four frames):
 AS17-P-1859, AS17-P-1861, AS17-P-1866, AS17-P-1868
 
 SSW part Nassau (26°50' South/ 176°30' East)
  High-Albedo swirl field at the south-southwestern part of crater Nassau's rim. See: LAC 104 (page 208) in the Clementine Atlas of the Moon.
 
 The very chaotic swirl field east of Birkeland
  See LROC Act-React Quickmap shortlink http://bit.ly/2n59fzC
  And LAC 104 in the Clementine Atlas of the Moon (Bussey/ Spudis).
 
 Hopmann
 5 sights in one crater (broken link?)
 
 

The typical shapes of lunar swirls (Art Nouveau, red cabbage, Jupiter's upper cloud deck, silver or gold paint, etc...).

From an artist's point of view, the lunar swirls have some sort of flowing Art Nouveau-related appearance (also known as Jugendstil).
  There's another way to detect similar curly shapes as those seen in lunar swirls. Cut red cabbage in half, and on the flat surface one shall see an extraordinary system of swirl-like shapes. Very much like the swirl-system in Mare Ingenii on the moon's far side! See wiki-photograph of the inner shapes of red cabbage.
  The upper cloud deck of Jupiter also shows these typical "red cabbage swirls", see APOD 7-4-2018 (Painting with Jupiter), and also this Juno close-up view
  The most well-known lunar swirl system (Reiner Gamma) and its northeastern and southwestern extensions show the same sort of curly shapes as those on the surface of silver or gold paint, after a gentle (short-duration) mix of the semi-fluid paint itself and the transparent oily substance which is hovering "above" it (in a can).
  After a firm (long-duration) mix of both the semi-fluid paint and the oily substance one shall see just the plain silver (or gold) result, ready to use with a brush or aerograph.
 
 

LPOD Articles

Bright Stuff
A New Swirl
A LUNAR NEBULA
BIRD’S FEET AND DROPPINGS?
APOLLO 17 - AN ALTERNATE REALITY
Airy Swirl
Swirlette
5 sights in one crater (swirl on the floor of Hopmann).

Bibliography

• Glotch, T et al (2010). Diviner Observations of Lunar Swirls - NLSI Lunar Science Forum (July) 2010.
• Mintz, B. (1994). A Swirl of Moondust, ASTRONOMY October 1994, pages 28 to 35.
• List from Hughes et al (2006) Optical Maturity and Magnetic Studies of Lunar Swirls. Lunar & Planetary Science Conf. 37, #123

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