O'Day (crater) explained

Coordinates:	-30.6°N 157.5°W
Diameter:	71 km
Depth:	Unknown
Colong:	203
Eponym:	Marcus O'Day

O'Day is a prominent lunar impact crater that is located on the far side of the Moon. It intrudes into the northwestern edge of Mare Ingenii, and the rim is lower on that side. To the northwest is the crater pair of Holetschek and Sierpinski. Southwest of O'Day lies the crater Seidel. It is named in honour of the American physicist Marcus O'Day.

The crater rim of O'Day remains sharp-edged, and the inner wall is terraced, especially in the northwestern half away from the mare. A small crater lies across the southern rim, and a tiny craterlet is located in the low inner rim between the crater and the mare. The floor is rough and irregular, with a double-peak at the midpoint.

Due to its prominent rays, O'Day is mapped as part of the Copernican System.^[1]

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to O'Day.

O'Day	Latitude	Longitude	Diameter
B	29.1° S	158.0° E	16 km
M	31.7° S	157.1° E	16 km
T	30.4° S	154.4° E	24 km

External links

• Lunar Map 103, showing O'Day and surroundings (Regional maps at the Lunar and Planetary Institute.)

References

• Book: Andersson . L. E. . Whitaker . E. A. . Ewen Whitaker . 1982 . NASA Catalogue of Lunar Nomenclature . NASA RP-1097 .
• Web site: Blue . Jennifer . July 25, 2007 . Gazetteer of Planetary Nomenclature . . 2007-08-05 .
• Book: Bussey . B. . Ben Bussey . Spudis . P. . Paul Spudis . 2004 . The Clementine Atlas of the Moon . . New York . 978-0-521-81528-4 .
• Book: Cocks . Elijah E. . Cocks . Josiah C. . 1995 . Who's Who on the Moon: A Biographical Dictionary of Lunar Nomenclature . Tudor Publishers . 978-0-936389-27-1 .
• Web site: McDowell . Jonathan . July 15, 2007 . Lunar Nomenclature . . 2007-10-24 .
• Menzel. D. H.. Minnaert. M.. Levin. B.. Dollfus. A.. Bell. B.. Report on Lunar Nomenclature by the Working Group of Commission 17 of the IAU. 10.1007/BF00171763. Space Science Reviews. 12. 2. 136–186. 1971. 1971SSRv...12..136M. 122125855.
• Book: Moore , Patrick . Patrick Moore

. Patrick Moore . 2001 . On the Moon . . 978-0-304-35469-6 .

• Book: Price , Fred W. . 1988 . The Moon Observer's Handbook . Cambridge University Press . 978-0-521-33500-3 .
• Book: Rükl , Antonín . Antonín Rükl

. Antonín Rükl . 1990 . Atlas of the Moon . . 978-0-913135-17-4 .

• Book: Webb , Rev. T. W. . Thomas William Webb

. Thomas William Webb . 1962 . Celestial Objects for Common Telescopes . 6th revised . Dover . 978-0-486-20917-3 .

• Book: Whitaker , Ewen A. . Ewen Whitaker

. Ewen Whitaker . 1999 . Mapping and Naming the Moon . Cambridge University Press . 978-0-521-62248-6 .

• Book: Wlasuk , Peter T. . 2000 . Observing the Moon . Springer . 978-1-85233-193-1 .

Notes and References

1. The geologic history of the Moon, 1987, Wilhelms, Don E.; with sections by McCauley, John F.; Trask, Newell J. USGS Professional Paper: 1348. Plate 11: Copernican System (online)