The scattered disc is a distant region of the Solar System that is
sparsely populated by icy minor planets, a subset of the broader family
of trans-Neptunian objects. The scattered disc objects have orbital
eccentricities ranging as high as 0.8, inclinations as high as 40° and
perihelia greater than 30 astronomical units. These extreme orbits are
believed to be the result of gravitational "scattering" by the gas
giants,
and the objects continue to be subject to perturbation by the planet
Neptune. While the nearest distance to the Sun approached by scattered
objects is about 30–35 AU, their orbits can extend well beyond 100 AU.
This makes scattered objects "among the most distant and cold objects
in the Solar System". The innermost portion of the scattered disc
overlaps with a torus-shaped region of orbiting objects known as the
Kuiper belt, but its outer limits reach much farther away from the Sun
and farther above and below the ecliptic than the belt proper. Due to
its unstable nature, astronomers now consider the scattered disc to be
the place of origin for most periodic comets observed in the Solar
System, with the centaurs, a population of icy bodies between Jupiter
and Neptune, being the intermediate stage in an object's migration from
the disc to the inner Solar System. Eventually, perturbations from the
giant planets send such objects towards the Sun, transforming them into
periodic comets. Many Oort cloud objects are also believed to have
originated in the scattered disc.
Read the rest of this article:
<http://en.wikipedia.org/wiki/Scattered_disc>
_______________________________
Today's selected anniversaries:
425:
Valentinian III became Emperor of the Western Roman Empire at the age
of six.
<http://en.wikipedia.org/wiki/Valentinian_III>
1642:
The Battle of Edgehill, the first pitched battle of the First English
Civil War between the Royalists and the Parliamentarians, was fought to
an inconclusive result near Edge Hill and Kineton in southern
Warwickshire.
<http://en.wikipedia.org/wiki/Battle_of_Edgehill>
1739:
Great Britain declared war on Spain, starting the War of Jenkins' Ear.
<http://en.wikipedia.org/wiki/War_of_Jenkins%27_Ear>
1955:
Prime Minister Ngo Dinh Diem defeated Emperor Bao Dai in a fraudulent
referendum supervised by his brother Ngo Dinh Nhu on the future of the
monarchy in South Vietnam.
<http://en.wikipedia.org/wiki/1955_State_of_Vietnam_referendum>
1956:
The Hungarian Revolution began as a peaceful student demonstration
which attracted thousands as it marched through central Budapest to the
Parliament building.
<http://en.wikipedia.org/wiki/Hungarian_Revolution_of_1956>
1983:
Lebanese Civil War: Suicide bombers destroyed two barracks in Beirut,
Lebanon, killing 241 U.S. servicemen and 58 French paratroopers of the
international peacekeeping force.
<http://en.wikipedia.org/wiki/1983_Beirut_barracks_bombing>
_____________________________
Wiktionary's word of the day:
haiku (n):
1. A Japanese poem of a specific form, consisting of three lines, the
first and last consisting of five morae, and the second consisting of
seven morae, usually with an emphasis on the season or a naturalistic
theme.
2. A three-line poem in any language, with five syllables in the first
and last lines and seven syllables in the second, usually with an
emphasis on the season or a naturalistic theme
<http://en.wiktionary.org/wiki/haiku>
___________________________
Wikiquote quote of the day:
We ought to hate very rarely, as it is too fatiguing; remain
indifferent to a great deal, forgive often and never forget.
--Sarah Bernhardt
<http://en.wikiquote.org/wiki/Sarah_Bernhardt>