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
_______________________________ 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)
_____________________ Wiktionary's Word of the day:
temerity: Reckless boldness; stupid bravery. (http://en.wiktionary.org/wiki/temerity)
_____________________ 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)