Volcanism on Io, a moon of Jupiter, produces lava flows, volcanic pits, and
plumes of sulfur and sulfur dioxide hundreds of kilometres high. This
volcanic activity was discovered in 1979 by Voyager 1 imaging scientists.
Observations of Io by passing spacecraft and Earth-based astronomers have
revealed more than 150 active volcanoes. Io's volcanism makes the satellite
one of only four known volcanically active worlds in the Solar System. First
predicted shortly before the Voyager 1 flyby, the heat source for Io's
volcanism comes from tidal heating produced by Io's forced orbital
eccentricity. Io's volcanism has led to the formation of hundreds of
volcanic centres and extensive lava formations, making the moon the most
volcanically active body in the solar system. Three different types of
volcanic eruptions have been identified, differing in duration, intensity,
lava effusion rate, and whether the eruption occurs within a volcanic pit.
Lava flows on Io, tens or hundreds of kilometres long, have primarily
basaltic composition, similar to lavas seen on Earth at shield volcanoes
such as Kīlauea in Hawaii. As a result of the presence of significant
quantities of sulfurous materials in Io's crust and on its surface, during
some eruptions, sulfur, sulfur dioxide gas, and pyroclastic material are
blown up to 500 kilometres (310 mi) into space, producing large,
umbrella-shaped volcanic plumes.
Read the rest of this article:
http://en.wikipedia.org/wiki/Volcanism_on_Io
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Today's selected anniversaries:
1444:
The Ottoman Empire under Sultan Murad II defeated the Polish and Hungarian
armies under Władysław III of Poland and John Hunyadi at the Battle of Varna
near Varna, Bulgaria in the final battle of the Crusade of Varna.
(
http://en.wikipedia.org/wiki/Battle_of_Varna)
1871:
"Dr. Livingstone, I presume?" – Journalist and explorer Henry Morton Stanley
located missing missionary and explorer David Livingstone in Ujiji, near
Lake Tanganyika in present-day Tanzania.
(
http://en.wikipedia.org/wiki/Henry_Morton_Stanley)
1928:
Hirohito was crowned the 124th Emperor of Japan.
(
http://en.wikipedia.org/wiki/Hirohito)
1969:
The children's television series Sesame Street debuted on the National
Educational Television network in the United States.
(
http://en.wikipedia.org/wiki/Sesame_Street)
1955:
Playwright and environmental activist Ken Saro-Wiwa and eight others from
the Movement for the Survival of the Ogoni People were executed by the
Nigerian military government.
(
http://en.wikipedia.org/wiki/Ken_Saro-Wiwa)
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Wiktionary's word of the day:
vouchsafe (v) To condescendingly grant a right, benefit, outcome,
etc.; to deign to acknowledge.
(
http://en.wiktionary.org/wiki/vouchsafe)
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Wikiquote quote of the day:
A free society is one where it is safe to be unpopular.
--Adlai Stevenson
(
http://en.wikiquote.org/wiki/Adlai_Stevenson)