The rings of Neptune were discovered in 1989 by the Voyager 2
spacecraft and are tenuous, faint and dusty, and resemble the rings of
Jupiter more closely than those of Saturn or Uranus. Neptune possesses
five known rings, each named for an astronomer who contributed
important work on the planet: the Galle, Le Verrier, Lassell, Arago and
Adams rings. Neptune also has a faint unnamed ring coincident with the
orbit of Neptunian moon Galatea. The rings of Neptune are made of
extremely dark material, likely organic compounds processed by
radiation similar to that found in the rings of Uranus. The proportion
of dust in the rings (between 20 and 70%) is high, while their optical
depth is low, at less than 0.1. Uniquely, the Adams ring is divided
into five discrete arcs, named Fraternité, Égalité 1 and 2, Liberté,
and Courage. The arcs occupy a narrow range of orbital longitudes and
are remarkably stable, having changed only slightly since their initial
detection in 1980. How the arcs maintain stability is still under
debate. However, their stability is probably related to the resonant
interaction between the Adams ring and its inner shepherd moon,
Galatea.
Read the rest of this article:
<http://en.wikipedia.org/wiki/Rings_of_Neptune>
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Today's selected anniversaries:
1643:
Thirty Years' War: The French led by Louis II de Bourbon, Prince de
Condé scored a decisive victory against the Spanish in Rocroi, France.
<http://en.wikipedia.org/wiki/Battle_of_Rocroi>
1780:
A combination of thick smoke, fog, and heavy cloud cover caused
complete darkness to fall on parts of Canada and the New England area
of the United States, requiring candles to be used from noon until
midnight.
<http://en.wikipedia.org/wiki/New_England%27s_Dark_Day>
1802:
Napoléon Bonaparte, First Consul of the French Republic, established
the Légion d'honneur order as a reward to commend civilians and
soldiers.
<http://en.wikipedia.org/wiki/L%C3%A9gion_d%27honneur>
1848:
Mexico ratified the Treaty of Guadalupe Hidalgo that was previously
signed to end the Mexican–American War, officially ceding present-day
California, Nevada, Utah, and other territory to the United States.
<http://en.wikipedia.org/wiki/Mexican_Cession>
1919:
Mustafa Kemal Atatürk traveled to Samsun to establish the Turkish
National Movement to resist the partitioning of the Ottoman Empire
after World War I, marking the start of the Turkish War of
Independence.
<http://en.wikipedia.org/wiki/Turkish_War_of_Independence>
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Wiktionary's word of the day:
Ruritanian (adj):
1. Of or having the characteristics of a place full of adventure,
romance, and intrigue, as in works of romantic fiction.
2. Used to describe a fictitious and generic foreign government or
person, as used to state a general or hypothetical situation
<http://en.wiktionary.org/wiki/Ruritanian>
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Wikiquote quote of the day:
Humankind consists of two sexes, woman and man. Is it possible that a
mass is improved by the improvement of only one part and the other
ignored? Is it possible that if half of a mass is tied to earth with
chains and the other half can soar into skies?
--Mustafa Kemal Atatürk
<http://en.wikiquote.org/wiki/Mustafa_Kemal_Atat%C3%BCrk>