The Moon is Earth's only natural satellite and the fifth largest moon
in the Solar System. The average centre-to-centre distance from the
Earth to the Moon is 384,403 kilometres (238,857 miles). The
gravitational pull at its surface is about a sixth of Earth's. The
Moon makes a complete orbit around the Earth every 27.3 days, and the
periodic variations in the geometry of the Earth–Moon–Sun system are
responsible for the lunar phases that repeat every 29.5 days. The
gravitational, centripetal forces generated by the rotation of the
Moon and Earth around a common axis, the barycentre, are largely
responsible for the tides on Earth. The Moon is the only celestial
body that humans have traveled to and landed on. The first artificial
object to escape Earth's gravity and pass near the Moon was the Soviet
Union's Luna 1, the first artificial object to impact the lunar
surface was Luna 2, and the first photographs of the normally occluded
far side of the Moon were made by Luna 3, all in 1959. The U.S. Apollo
program has achieved the first (and only) manned missions to date,
resulting in six landings between 1969 and 1972. Human exploration of
the Moon ceased with the conclusion of the Apollo program, although as
of 2007, several countries have announced plans to send either people
or robotic spacecraft to the Moon. On 4 December, 2006, NASA outlined
plans for a permanent base on the Moon as part of preparation for a
voyage to Mars.
Read the rest of this article:
http://en.wikipedia.org/wiki/Moon
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Today's selected anniversaries:
1565:
Pedro Menéndez de Avilés founded St. Augustine in Spanish Florida,
the oldest continually occupied European settlement in the continental
United States.
(
http://en.wikipedia.org/wiki/St._Augustine%2C_Florida)
1640:
Bishops' Wars: Scottish Covenanter forces led by Alexander Leslie
defeated Charles I's English army at the Battle of Newburn near
Newburn, England.
(
http://en.wikipedia.org/wiki/Battle_of_Newburn)
1845:
The first issue of the popular-science magazine Scientific American
was published, currently the oldest continuously published magazine in
the United States.
(
http://en.wikipedia.org/wiki/Scientific_American)
1850:
German composer Richard Wagner's romantic opera Lohengrin, featuring
the Bridal Chorus, was first performed under the direction of
Hungarian composer Franz Liszt in Weimar, Germany.
(
http://en.wikipedia.org/wiki/Lohengrin_%28opera%29)
1963:
Martin Luther King, Jr. delivered his "I Have a Dream" speech from
the steps of the Lincoln Memorial in Washington, D.C., describing his
desire for a future where blacks and whites would coexist harmoniously
as equals.
(
http://en.wikipedia.org/wiki/I_Have_a_Dream)
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Wiktionary's Word of the day:
temerity: Reckless boldness; stupid bravery.
(
http://en.wiktionary.org/wiki/temerity)
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Wikiquote of the day:
Moderation, the Golden Mean, the Aristonmetron, is the secret of
wisdom and of happiness. But it does not mean embracing an
unadventurous mediocrity: rather it is an elaborate balancing-act, a
feat of intellectual skill demanding constant vigilance. Its aim is a
reconciliation of opposites. -- Robertson Davies
(
http://en.wikiquote.org/wiki/Robertson_Davies)