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Messier (crater)
Encyclopedia
Messier is a relatively young lunar impact crater
located on the Mare Fecunditatis
. The crater has a discernible oblong
shape that is not caused by foreshortening. The longer dimension is oriented in an east–west direction.
Just to the west lies Messier A, a similar-sized crater with an oblong, doublet form. The longer dimension of this crater is oriented north–south, at right angle
s to Messier. This crater also has a curved bulge extending to the west.
The interiors of Messier and Messier A have a higher albedo than the surrounding mare
. There is also a dark streak in the center of each crater. Two prominent, nearly linear rays
extend westwards from the rim of Messier A, continuing over 100 kilometers towards the east edge of Mare Fecunditatis
. The mare surface around the craters is also lightly marked by rays from other craters.
It is theorized that Messier crater was formed by an impact at a very low angle, and that Messier A could have formed following a rebound by the impacting body. The low angle of impact may also explain the asymmetrical ray system.
To the northwest of Messier A is a long, narrow rille
.
This crater is named in honor of the French astronomer Charles Messier
(1730–1817).
The following crater has been renamed by the IAU
.
Messier A has been called W. H. Pickering
, but this was never officially sanctioned by the IAU. A different crater has since been named for Pickering.
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
located on the Mare Fecunditatis
Mare Fecunditatis
Mare Fecunditatis is a lunar mare which is 840 km in diameter. The Fecuditatis basin formed in the Pre-Nectarian epoch, while the basin material surrounding the mare is of the...
. The crater has a discernible oblong
Rectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The term "oblong" is occasionally used to refer to a non-square rectangle...
shape that is not caused by foreshortening. The longer dimension is oriented in an east–west direction.
Just to the west lies Messier A, a similar-sized crater with an oblong, doublet form. The longer dimension of this crater is oriented north–south, at right angle
Right angle
In geometry and trigonometry, a right angle is an angle that bisects the angle formed by two halves of a straight line. More precisely, if a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles...
s to Messier. This crater also has a curved bulge extending to the west.
Lunar mare
The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and...
. There is also a dark streak in the center of each crater. Two prominent, nearly linear rays
Ray system
A ray system comprises radial streaks of fine ejecta thrown out during the formation of an impact crater, looking a bit like many thin spokes coming from the hub of a wheel. The rays can extend for lengths up to several times the diameter of their originating crater, and are often accompanied by...
extend westwards from the rim of Messier A, continuing over 100 kilometers towards the east edge of Mare Fecunditatis
Mare Fecunditatis
Mare Fecunditatis is a lunar mare which is 840 km in diameter. The Fecuditatis basin formed in the Pre-Nectarian epoch, while the basin material surrounding the mare is of the...
. The mare surface around the craters is also lightly marked by rays from other craters.
It is theorized that Messier crater was formed by an impact at a very low angle, and that Messier A could have formed following a rebound by the impacting body. The low angle of impact may also explain the asymmetrical ray system.
To the northwest of Messier A is a long, narrow rille
Rille
Rille is typically used to describe any of the long, narrow depressions in the lunar surface that resemble channels. Typically a rille can be up to several kilometers wide and hundreds of kilometers in length...
.
This crater is named in honor of the French astronomer Charles Messier
Charles Messier
Charles Messier was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters that came to be known as the 110 "Messier objects"...
(1730–1817).
Satellite craters
By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Messier.| Messier | Latitude | Longitude | Diameter |
|---|---|---|---|
| A | 2.0° S | 47.0° E | 11 x 13 km |
| B | 0.9° S | 48.0° E | 6 km |
| D | 3.6° S | 46.3° E | 8 km |
| E | 3.3° S | 45.4° E | 5 km |
| J | 1.5° S | 52.1° E | 4 km |
| L | 1.2° S | 51.8° E | 6 km |
The following crater has been renamed by the IAU
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
.
- Messier G - See Lindbergh (crater)Lindbergh (crater)Lindbergh is a small lunar crater that is located in the western part of the Mare Fecunditatis. It lies to the west of the flooded crater Bilharz, and northeast of Ibn Battuta. Lindbergh was previously designated Messier G before being given its name by the IAU...
.
Messier A has been called W. H. Pickering
William Henry Pickering
William Henry Pickering was an American astronomer, brother of Edward Charles Pickering. He was elected a Fellow of the American Academy of Arts and Sciences in 1883.-Work:...
, but this was never officially sanctioned by the IAU. A different crater has since been named for Pickering.