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M-type Asteroid
M-type (aka M-class) asteroids are a spectral class of asteroids which appear to contain higher concentrations of metal phases (e.g. iron-nickel) than other asteroid classes, and are widely thought to be the source of iron meteorites. Definition Asteroids are classified as M-type based upon their generally featureless and flat to red-sloped absorption spectra in the visible to near-infrared and their moderate optical albedo. Along with the spectrally similar E-type and P-type asteroids (both categories E and P were formerly type-M in older systems), they are included in the larger X-type asteroid group and are distinguishable only by optical albedo: : Characteristics Composition Although widely assumed to be metal-rich (the reason for use of "M" in the classification), the evidence for a high metal content in the M-type asteroids is only indirect, though highly plausible. Their spectra are similar to those of iron meteorites and enstatite chondrites, and radar observations ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rosetta Triumphs At Asteroid Lutetia
Rosetta or Rashid (; ar, رشيد ' ; french: Rosette ; cop, ϯⲣⲁϣⲓⲧ ''ti-Rashit'', Ancient Greek: Βολβιτίνη ''Bolbitinē'') is a port city of the Nile Delta, east of Alexandria, in Egypt's Beheira governorate. The Rosetta Stone was discovered there in 1799. Founded around the 9th century on site of the ancient town Bolbitine, Rosetta boomed with the decline of Alexandria following the Ottoman conquest of Egypt in 1517, only to wane in importance after Alexandria's revival. During the 19th century, it was a popular British tourist destination, known for its Ottoman mansions, citrus groves and relative cleanliness. Etymology The name of the town most likely comes from an Arabic name '' Rašīd'' (meaning "guide") and was transcribed and corrupted in numerous ways – the name ''Rexi'' was used by the Crusaders in Middle Ages and ''Rosetta'' or ''Rosette'' ("little rose" in Italian and French respectively) was used by the French at the time of Napoleon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
