Brightness of Selected Features
Contents
Lunar Brightness
(see glossary entry: [/Albedo%20feature Albedo feature])Table of Contents
Description
The Moon is a place of strong brightness variations, sometimes seen in one view while looking at a brilliant peak sticking up from a black shadow. But the only way to make consistent and reliable determinations of lunar brightness is to observe at full Moon, when the Sun and the Earth see the Moon from nearly the same angle.
Brightness Comparison
There are two ways to determine lunar brightness - visual estimates and photometric measurements. The great German observer [/Johann%20Schr%C3%B6ter Johann Schröter] developed the visual scale that was popularized by [/Elger Thomas Elger] in the late 1880's. Photoelectric photometry started in the 1920's and is now done not just for a single spot on the lunar surface, but with ccd detectors, for broad areas. The weakness of the visual estimates is their subjectivity. Nonetheless, the old visual estimates and old spot measurements still have value. Here is a comparison of the visual brightness scale, N (0 is the absolute black of shadows and 10 is the brightest spot on the Moon - the central peaks of Aristarchus) and measured albedos (A) - the measured reflectivity of the surface (0 means incident light is totally absorbed - like a black hole; 1.0 means 100% of incident light is reflected). This table comes from the article "Photometry of the Moon" by VG Fessenkov in the 1962 book Physics and Astronomy of the Moon (edited by Z Kopal). - tychocrater tychocrater Sep 3, 2007
| Feature |
Brightness Scale (N) |
Albedo (A) |
|
[/Grimaldi Grimaldi] & [/Riccioli Riccioli] floors |
1.0 |
0.061 |
|
[/Boscovich Boscovich] floor |
1.5 |
0.067 |
|
[/Julius%20Caesar Julius Caesar] & [/Endymion Endymion] floors |
2.0 |
0.074 |
|
[/Pitatus Pitatus] & [/Marius Marius] floors |
2.5 |
0.081 |
|
[/Taruntius Taruntius], [/Plinius Plinius], [/Flamsteed Flamsteed], [/Theophilus Theophilus], [/Mercator Mercator] floors |
3.0 |
0.088 |
|
[/Hansen Hansen], [/Archimedes Archimedes] & [/Mersenius Mersenius] floors |
3.5 |
0.095 |
|
[/Ptolemaeus Ptolemaeus], [/Manilius Manilius] & [/Guericke Guericke] floors |
4.0 |
0.102 |
|
[/Aristillus Aristillus] environs |
4.5 |
0.109 |
|
[/Arago Arago], [/Lansberg Lansberg] & [/Bullialdus Bullialdus] walls, [/Kepler Kepler] environs |
5.0 |
0.115 |
|
[/Picard Picard] & [/Timocharis Timocharis] walls, rays of [/Copernicus Copernicus] |
5.5 |
0.122 |
|
[/Macrobius Macrobius], [/Kant Kant], [/Bessel Bessel], [/M%C3%B6sting Mösting] & [/Flamsteed Flamsteed] walls |
6.0 |
0.129 |
|
[/Lagrange Lagrange], [/Mons%20La%20Hire Mons La Hire] & [/Theaetetus Theaetetus] walls |
6.5 |
0.135 |
|
[/Theon%20Junior Theon Junior], [/Ariadaeus Ariadaeus], [/Behaim Behaim] & Bode B walls |
7.0 |
0.142 |
|
[/Euclides Euclides], [/Ukert Ukert] & [/Hortensius Hortensius] walls |
7.5 |
0.149 |
|
[/Godin Godin], [/Copernicus Copernicus] & [/Bode Bode] walls |
8.0 |
0.156 |
|
[/Proclus Proclus], Bode A & Hipparchus C walls |
8.5 |
0.163 |
|
[/Mersenius Mersenius] & Mosting A walls |
9.0 |
0.169 |
|
[/Aristarchus Aristarchus] interior |
9.5 |
0.176 |
|
[/Aristarchus Aristarchus] central peaks |
10.0 |
0.183 |
The approximate mathematical relation between visual brightness estimate, N, and measured albedo, A is:
- A = 0.047 - 0.136 x N
Additional Information
- [/ALPO ALPO]'s Selected Areas Project
LPOD Articles
Bibliography
Brightness of Lunar Features, Chuck Wood's Moon Web site
This page has been edited 1 times. The last modification was made by - tychocrater tychocrater on Jun 13, 2009 3:24 pm - mgx2
