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1.1 billion years, not million. Come on, people.
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{{short description|Lunar geologic period}}
{{one source|date=October 2013}}
{{one source|date=October 2013}}
{{Infobox geologic timespan
{{Lunar-geo-time}}
| name = Copernican
| manual_color = rgb(127.0, 127.0, 127.0)
| top_bar = Lunar
| time_start = 1100
| time_end = 0
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<!--Chronology-->
| timeline = Lunar periods
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<!--Etymology-->
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<!--Usage Information-->
| celestial_body = Moon
| usage =
| timescales_used = Lunar Geologic Timescale
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<!--Definition-->
| chrono_unit = Period
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The '''Copernican Period''' in the [[lunar geologic timescale]] runs from approximately 1.1 billion years ago to the present day. The base of the Copernican period is defined by impact craters that possess bright optically immature [[ray system]]s. The [[Copernicus (lunar crater)|crater Copernicus]] is a prominent example of rayed crater, but it does not mark the base of the Copernican period.
The '''Copernican Period''' in the [[lunar geologic timescale]] runs from approximately 1.1 billion years ago to the present day. The base of the Copernican period is defined by impact craters that possess bright optically immature [[ray system]]s. The [[Copernicus (lunar crater)|crater Copernicus]] is a prominent example of rayed crater, but it does not mark the base of the Copernican period.
[[Image:Copernican System nearside plate 11A Wilhelms1987.jpg|thumb|right|300px|The Copernican System on the near side of the moon]]
[[Image:Copernican System nearside plate 11A Wilhelms1987.jpg|thumb|right|300px|The Copernican System on the near side of the Moon (Wilhelms, 1987)]]
[[Image:Copernican System farside plate 11B Wilhelms1987.jpg|thumb|right|300px|The Copernican System on the far side of the moon]]
[[Image:Copernican System farside plate 11B Wilhelms1987.jpg|thumb|right|300px|The Copernican System on the far side of the Moon (Wilhelms, 1987)]]


Copernican age deposits are mostly represented by crater [[ejecta]], but a small area of mare [[basalt]] has covered part of (and is thus younger than) some of the rays of the Copernican crater [[Lichtenberg (crater)|Lichtenberg]], and therefore the basalt is mapped as Copernican age.<ref>The geologic history of the Moon, 1987, Wilhelms, Don E.; with sections by McCauley, John F.; Trask, Newell J. USGS Professional Paper: 1348. ([https://pubs.er.usgs.gov/publication/pp1348 online])</ref>
Copernican age deposits are mostly represented by crater [[ejecta]], but a small area of mare [[basalt]] has covered part of (and is thus younger than) some of the rays of the Copernican crater [[Lichtenberg (crater)|Lichtenberg]], and therefore the basalt is mapped as Copernican age.<ref>{{cite web |title= The geologic history of the Moon |date= 1987 |last1= Wilhelms |first1= Don E. |last2= McCauley |first2= John F. |last3= Trask |first3= Newell J. |publisher= USGS |id=Professional paper 1348 |url= https://pubs.er.usgs.gov/publication/pp1348 }}</ref>


==Definition==
==Definition==
The base of the Copernican period is defined based on the recognition that freshly excavated materials on the lunar surface are generally "bright" and that they become darker over time as a result of [[space weathering]] processes. Operationally, this period was originally defined as the time at which impact craters "lost" their bright [[ray system]]s. This definition, however, has recently been subjected to some criticism as some crater rays are bright for compositional reasons that are unrelated to the amount of space weathering they have incurred. In particular, if the ejecta from a crater formed in the highlands (which is composed of bright anorthositic materials) is deposited on the low albedo mare, it will remain bright even after being space weathered.
The base of the Copernican period is defined based on the recognition that freshly excavated materials on the lunar surface are generally "bright" and that they become darker over time as a result of [[space weathering]] processes. Operationally, this period was originally defined as the time at which impact craters "lost" their bright [[ray system]]s. This definition, however, has recently been subjected to some criticism as some crater rays are bright for compositional reasons that are unrelated to the amount of space weathering they have incurred. In particular, if the ejecta from a crater formed in the highlands (which is composed of bright [[Anorthosite|anorthositic]] materials) is deposited on the low albedo mare, it will remain bright even after being space weathered.


{{Timeline_Lunar_Geological_Timescale}}
{{Timeline_Lunar_Geological_Timescale}}

==Examples==
Other than Copernicus itself, there are many examples of Copernican craters. Large examples on the near side include [[Tycho (lunar crater)|Tycho]], [[Aristillus (crater)|Aristillus]], [[Autolycus (crater)|Autolycus]], [[Stevinus (crater)|Stevinus]], [[Kepler (lunar crater)|Kepler]], [[Theophilus (crater)|Theophilus]], [[Taruntius (crater)|Taruntius]], [[Eudoxus (lunar crater)|Eudoxus]], [[Bürg (crater)|Bürg]], [[Römer (crater)|Römer]], [[Harpalus (crater)|Harpalus]], [[Carpenter (crater)|Carpenter]], [[Philolaus (crater)|Philolaus]], [[Anaxagoras (crater)|Anaxagoras]], [[Glushko (crater)|Glushko]], [[Hayn (crater)|Hayn]], [[Zucchius (crater)|Zucchius]], and [[Rutherfurd (crater)|Rutherfurd]]. Examples on the far side include [[Ohm (crater)|Ohm]], [[Jackson (crater)|Jackson]], [[King (crater)|King]], [[Necho (crater)|Necho]], [[Giordano Bruno (crater)|Giordano Bruno]], [[O'Day (crater)|O'Day]], [[Crookes (crater)|Crookes]], [[Robertson (crater)|Robertson]], [[Vavilov (crater)|Vavilov]], and [[Sharonov (lunar crater)|Sharonov]].<ref>[https://www.lpi.usra.edu/resources/mapcatalog/UGM/ Unified Geologic Map of the Moon], C. M. Fortezzo, P. D. Spudis, S. L. Harrel, 2020. United States Geological Survey.</ref>

<gallery heights="200px" mode="packed">
File:Copernican crater AS15-P-9337.png|500 m diameter crater with rays in Mare Serenitatis
File:Copernicus (LRO) 2.png|Copernicus
File:Tycho LRO.png|Tycho
File:Hayn crater LROC WAC.jpg|Hayn
File:Jackson LRO WAC.jpg|Jackson
File:Necho crater AS14-70-9671.jpg|Necho ([[Apollo 14]])
Image:Crookes crater as08-13-2318hr.jpg|Interior of Crookes ([[Apollo 8]])
</gallery>

Many craters visited by the [[Apollo program|Apollo]] astronauts were of Copernican age. These include [[North Ray (crater)|North Ray]] and [[South Ray (crater)|South Ray]] on [[Apollo 16]], which were dated by cosmic ray exposure to approximately 50 million and 2 million years age, respectively.


==Relationship to Earth's geologic time scale==
==Relationship to Earth's geologic time scale==
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==References==
==References==
{{reflist}}
{{reflist}}
* {{cite web | url = http://www.psrd.hawaii.edu/Sept04/LunarRays.html | title = Lunar Crater Rays Point to a New Lunar Time Scale | last = Martel, L. M. V. | publisher = Planetary Science Research Discoveries | date = 2004-09-28}}
* {{cite web |url= http://www.psrd.hawaii.edu/Sept04/LunarRays.html |title= Lunar Crater Rays Point to a New Lunar Time Scale |last= Martel |first= Linda M. V. |publisher= Planetary Science Research Discoveries (PSRD) |website= [[University of Hawaii|Hawai'i Institute of Geophysics and Planetology]] (HIGP) |date= 2004-09-28}}


[[Category:Lunar geologic periods]]
[[Category:Lunar geologic periods]]

Revision as of 02:48, 7 January 2024

Copernican
1100 – 0 Ma
Chronology
Usage information
Celestial bodyEarth's Moon
Time scale(s) usedLunar Geologic Timescale
Definition
Chronological unitPeriod

The Copernican Period in the lunar geologic timescale runs from approximately 1.1 billion years ago to the present day. The base of the Copernican period is defined by impact craters that possess bright optically immature ray systems. The crater Copernicus is a prominent example of rayed crater, but it does not mark the base of the Copernican period.

The Copernican System on the near side of the Moon (Wilhelms, 1987)
The Copernican System on the far side of the Moon (Wilhelms, 1987)

Copernican age deposits are mostly represented by crater ejecta, but a small area of mare basalt has covered part of (and is thus younger than) some of the rays of the Copernican crater Lichtenberg, and therefore the basalt is mapped as Copernican age.[1]

Definition

The base of the Copernican period is defined based on the recognition that freshly excavated materials on the lunar surface are generally "bright" and that they become darker over time as a result of space weathering processes. Operationally, this period was originally defined as the time at which impact craters "lost" their bright ray systems. This definition, however, has recently been subjected to some criticism as some crater rays are bright for compositional reasons that are unrelated to the amount of space weathering they have incurred. In particular, if the ejecta from a crater formed in the highlands (which is composed of bright anorthositic materials) is deposited on the low albedo mare, it will remain bright even after being space weathered.

Early ImbrianLate ImbrianPre-NectarianNectarianEratosthenianCopernican period
Millions of years before present


Examples

Other than Copernicus itself, there are many examples of Copernican craters. Large examples on the near side include Tycho, Aristillus, Autolycus, Stevinus, Kepler, Theophilus, Taruntius, Eudoxus, Bürg, Römer, Harpalus, Carpenter, Philolaus, Anaxagoras, Glushko, Hayn, Zucchius, and Rutherfurd. Examples on the far side include Ohm, Jackson, King, Necho, Giordano Bruno, O'Day, Crookes, Robertson, Vavilov, and Sharonov.[2]

  • 500 m diameter crater with rays in Mare Serenitatis
    500 m diameter crater with rays in Mare Serenitatis
  • Copernicus
    Copernicus
  • Tycho
    Tycho
  • Hayn
    Hayn
  • Jackson
    Jackson
  • Necho (Apollo 14)
    Necho (Apollo 14)
  • Interior of Crookes (Apollo 8)
    Interior of Crookes (Apollo 8)

Many craters visited by the Apollo astronauts were of Copernican age. These include North Ray and South Ray on Apollo 16, which were dated by cosmic ray exposure to approximately 50 million and 2 million years age, respectively.

Relationship to Earth's geologic time scale

Its Earth equivalents are the Neoproterozoic era of the Proterozoic eon and the whole of the Phanerozoic eon. So, while animal life bloomed on Earth, the Moon's geologic activity was coming to an end.

References

  1. ^ Wilhelms, Don E.; McCauley, John F.; Trask, Newell J. (1987). "The geologic history of the Moon". USGS. Professional paper 1348.
  2. ^ Unified Geologic Map of the Moon, C. M. Fortezzo, P. D. Spudis, S. L. Harrel, 2020. United States Geological Survey.
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