Bailly (crater)

Bailly
	Clementine mosaic
Coordinates	66°48′S 69°24′W / 66.8°S 69.4°W
Diameter	300.56 km (186.76 mi)
Depth	4.86 km (3.02 mi)
Colongitude	65° at sunrise
Formation	Nectarian
Eponym	Jean S. Bailly

Bailly is a lunar impact crater that is located near the south-west limb of the Moon.^[5]^[6] It is the largest walled plain on the visible face of the Moon,^[7] spanning a diameter of 300 km.^[1] The oblique viewing angle gives the crater a foreshortened appearance, and the location near the limb can limit visibility due to libration.^[8] The most favorable time for viewing this feature is near the full moon when the terminator is crossing the crater wall.

This formation was named after French astronomer Jean S. Bailly (1736-1793). Its designation was officially adopted by the International Astronomical Union in 1935.^[1] The name was introduced into lunar nomenclature by Johann H. Schröter in 1791.^[9]^{: 101, 218}

Description

Location of Bailly crater, with its marking at the bottom

This class of formation is known as a peak ring basin, which has a single interior topographic ring or a discontinuous ring of peaks with no central peak.^[10] It is the largest crater on the near side of the Moon. In area it is comparable in size to a small mare. It lies north of the crater Le Gentil and east of Hausen.^[11]^: 136 Further west of Bailly are the (unofficially named) Montes Dörfel mountains.

Due to the size and the worn state of this crater, it is estimated to be more than 3 billion years old, and is part of the Nectarian system.^[3]^[4] Bailly's uneven crater floor has remained free of basaltic flooding, and it is covered with a multitude of ridges and craters. The entire crater has been battered and worn, and the outer ramparts are eroded and in some places have even been worn away by myriad impacts. It likely is covered by ejecta from Hausen crater.^[12] If Bailly ever possessed a central peak, it is no longer discernible. However, the battered remains of a peak ring is possible.^[13]^[6] Due to its current condition, observers have termed this walled plain a 'field of ruins'.^[7]

Satellite craters

The south-eastern part of the crater is home to two notable craters, designated Bailly A and Bailly B.^[8] These craters overlap, and Bailly A lies across the rim of Bailly's mountainous wall. Selenographer Giovanni Battista Riccioli named Bailly B, Bartolus for fellow Ferrarese Jesuit Daniello Bartoli (1608-1685) in his Almagestum novum (1651).^[9]^: 211 The name was not recognized by the IAU.

By convention the following features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Bailly.^[14]

Bailly^[11]^: 292	Coordinates	Diameter
A	69°17′S 59°34′W / 69.28°S 59.57°W / -69.28; -59.57 (Bailly A)	43 km
B	68°44′S 63°15′W / 68.74°S 63.25°W / -68.74; -63.25 (Bailly B)	62 km
C	65°47′S 70°20′W / 65.79°S 70.34°W / -65.79; -70.34 (Bailly C)	19 km
D	65°15′S 72°23′W / 65.25°S 72.38°W / -65.25; -72.38 (Bailly D)	27 km
E	62°27′S 65°45′W / 62.45°S 65.75°W / -62.45; -65.75 (Bailly E)	16 km
F	67°28′S 69°35′W / 67.46°S 69.59°W / -67.46; -69.59 (Bailly F)	17 km
G	65°38′S 59°28′W / 65.63°S 59.47°W / -65.63; -59.47 (Bailly G)	19 km
H	63°34′S 62°35′W / 63.57°S 62.59°W / -63.57; -62.59 (Bailly H)	13 km
K	62°44′S 76°43′W / 62.73°S 76.71°W / -62.73; -76.71 (Bailly K)	19 km
L	60°43′S 71°08′W / 60.71°S 71.13°W / -60.71; -71.13 (Bailly L)	21 km
M	61°10′S 67°31′W / 61.16°S 67.51°W / -61.16; -67.51 (Bailly M)	20 km
N	60°32′S 63°41′W / 60.53°S 63.68°W / -60.53; -63.68 (Bailly N)	11 km
O	69°35′S 56°55′W / 69.59°S 56.92°W / -69.59; -56.92 (Bailly O)	19 km
P	59°34′S 60°40′W / 59.57°S 60.67°W / -59.57; -60.67 (Bailly P)	14 km
R	64°40′S 79°11′W / 64.66°S 79.18°W / -64.66; -79.18 (Bailly R)	17 km
T	66°29′S 73°50′W / 66.49°S 73.83°W / -66.49; -73.83 (Bailly T)	19 km
U	71°14′S 76°02′W / 71.24°S 76.03°W / -71.24; -76.03 (Bailly U)	24 km
V	71°55′S 81°27′W / 71.91°S 81.45°W / -71.91; -81.45 (Bailly V)	32 km
Y	61°02′S 65°36′W / 61.04°S 65.60°W / -61.04; -65.60 (Bailly Y)	14 km
Z	60°13′S 65°52′W / 60.22°S 65.86°W / -60.22; -65.86 (Bailly Z)	13 km

References

1 2 3 "Bailly". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
↑ Williams, Kevin K.; Zuber, Maria T. (January 1998). "Measurement and Analysis of Lunar Basin Depths from Clementine Altimetry". Icarus. 131 (1): 107–122. Bibcode:1998Icar..131..107W. doi:10.1006/icar.1997.5856.
1 2 Byrne, Charles J. (2015). The Moon's Largest Craters and Basins: Images and Topographic Maps from LRO, GRAIL, and Kaguya. Physics and Astronomy. Springer. pp. 8–9. ISBN 978-3-319-22032-1.
1 2 Wilhelms, Don E.; Byrne, Charles J. (January 23, 2009). "Stratigraphy of Lunar Craters". Archived from the original on 2021-02-18. Retrieved 2021-02-18.
↑ Webb, Rev. T. W. (1962). Celestial Objects for Common Telescopes (6th revised ed.). Dover. pp. 138, 154–159. Reprint: ISBN 978-0-486-20917-3
1 2 Wood, Chuck (November 24, 2006). "A Little Basin". Lunar Photo of the Day. Archived from the original on 2007-04-01. Retrieved 2006-11-28.
1 2 Moore, Patrick (2001). On the Moon. Sterling Publishing Co. p. 197. ISBN 978-0-304-35469-6.
1 2 Grego, Peter (2005). The Moon and How to Observe It. Astronomers' Observing Guides Series. London: Springer-Verlag. pp. 181–182. ISBN 1-85233-748-6.
1 2 Whitaker, Ewen A. (1999). Mapping and Naming the Moon. Cambridge University Press. ISBN 978-0-521-62248-6.
↑ Baker, David M. H.; et al. (August 2011). "The transition from complex crater to peak-ring basin on the Moon: New observations from the Lunar Orbiter Laser Altimeter (LOLA) instrument". Icarus. 214 (2): 377–393. Bibcode:2011Icar..214..377B. doi:10.1016/j.icarus.2011.05.030.
1 2 Bussey, B.; Spudis, P. (2004). The Clementine Atlas of the Moon. New York: Cambridge University Press. ISBN 978-0-521-81528-4.
↑ Cook, A. C.; et al. (May 2000). "Lunar polar topography derived from Clementine stereoimages". Journal of Geophysical Research. 105 (E5): 12023–12034. Bibcode:2000JGR...10512023C. doi:10.1029/1999JE001083.
↑ Hartmann, W. K.; Wood, C. A. (July 1971). "Moon: Origin and evolution of multi-ring basins". The Moon. 3 (1): 3–78. Bibcode:1971Moon....3....3H. doi:10.1007/BF00620390.
↑ Grego, P. (2015). "Satellite Crater". In Hargitai, H.; Kereszturi, Á. (eds.). Encyclopedia of Planetary Landforms. New York, NY: Springer. doi:10.1007/978-1-4614-3134-3_328.

[GPN-1] 1 2 3 "Bailly". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.

[Williams_Zuber_1998-2] Williams, Kevin K.; Zuber, Maria T. (January 1998). "Measurement and Analysis of Lunar Basin Depths from Clementine Altimetry". Icarus. 131 (1): 107–122. Bibcode:1998Icar..131..107W. doi:10.1006/icar.1997.5856.

[Byrne_2015-3] 1 2 Byrne, Charles J. (2015). The Moon's Largest Craters and Basins: Images and Topographic Maps from LRO, GRAIL, and Kaguya. Physics and Astronomy. Springer. pp. 8–9. ISBN 978-3-319-22032-1.

[Wilhelms_Byrne_2009-4] 1 2 Wilhelms, Don E.; Byrne, Charles J. (January 23, 2009). "Stratigraphy of Lunar Craters". Archived from the original on 2021-02-18. Retrieved 2021-02-18.

[Webb_1962-5] Webb, Rev. T. W. (1962). Celestial Objects for Common Telescopes (6th revised ed.). Dover. pp. 138, 154–159. Reprint: ISBN 978-0-486-20917-3

[Wood_2006-6] 1 2 Wood, Chuck (November 24, 2006). "A Little Basin". Lunar Photo of the Day. Archived from the original on 2007-04-01. Retrieved 2006-11-28.

[Moore_2001-7] 1 2 Moore, Patrick (2001). On the Moon. Sterling Publishing Co. p. 197. ISBN 978-0-304-35469-6.

[Grego_2005-8] 1 2 Grego, Peter (2005). The Moon and How to Observe It. Astronomers' Observing Guides Series. London: Springer-Verlag. pp. 181–182. ISBN 1-85233-748-6.

[Whitaker_1999-9] 1 2 Whitaker, Ewen A. (1999). Mapping and Naming the Moon. Cambridge University Press. ISBN 978-0-521-62248-6.

[Baker_et_al_2011-10] Baker, David M. H.; et al. (August 2011). "The transition from complex crater to peak-ring basin on the Moon: New observations from the Lunar Orbiter Laser Altimeter (LOLA) instrument". Icarus. 214 (2): 377–393. Bibcode:2011Icar..214..377B. doi:10.1016/j.icarus.2011.05.030.

[Bussey_Spudis_2004-11] 1 2 Bussey, B.; Spudis, P. (2004). The Clementine Atlas of the Moon. New York: Cambridge University Press. ISBN 978-0-521-81528-4.

[Cook_et_al_2000-12] Cook, A. C.; et al. (May 2000). "Lunar polar topography derived from Clementine stereoimages". Journal of Geophysical Research. 105 (E5): 12023–12034. Bibcode:2000JGR...10512023C. doi:10.1029/1999JE001083.

[Hartmann_Wood_1971-13] Hartmann, W. K.; Wood, C. A. (July 1971). "Moon: Origin and evolution of multi-ring basins". The Moon. 3 (1): 3–78. Bibcode:1971Moon....3....3H. doi:10.1007/BF00620390.

[Grego_2015-14] Grego, P. (2015). "Satellite Crater". In Hargitai, H.; Kereszturi, Á. (eds.). Encyclopedia of Planetary Landforms. New York, NY: Springer. doi:10.1007/978-1-4614-3134-3_328.

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