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Wikipedia is a multilingual, Web-based, free content encyclopedia project, written collaboratively by volunteers from all around the world. Since its creation in 2001, Wikipedia has grown rapidly into one of the largest reference web sites, attracting at least 684 million visitors yearly by 2008. There are more than 75,000 active contributors working on more than 10,000,000 articles in more than 250 languages. As of today, there are 6,823,776 articles in English. Every day hundreds of thousands of visitors from around the world make tens of thousands of edits and create thousands of new articles to enhance the knowledge held by the Wikipedia encyclopedia. (More....) |
Mars is the fourth planet from the Sun. It was formed approximately 4.5 billion years ago, is a terrestrial planet and is the second smallest of the Solar System's planets with a diameter of 6,779 km (4,212 mi). A Martian solar day (sol) is 24.5 hours and a Martian solar year is 1.88 Earth years (687 Earth days). Mars has two small and irregular natural satellites: Phobos and Deimos. Carbon dioxide is substantially present in Mars's polar ice caps and thin atmosphere. It has the highest mountain in the solar system, Olympus Mons, and the largest canyon, Valles Marineris. There are large annual temperature swings on the surface, between −78.5 °C (−109.3 °F) and 5.7 °C (42.3 °F) – similar to Earth's seasons. Due to its geological history, the possibility of past or present life on Mars remains of great scientific interest. Mars has been explored by uncrewed spacecraft and rovers, and is an attractive target for future human exploration missions. (This article is part of a featured topic: Solar System.)
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Wikipedia's sister projectsWikipedia is written by volunteer editors and hosted by the Wikimedia Foundation, a non-profit organization that also hosts a range of other volunteer projects:
Wikipedia languagesThis Wikipedia is written in English. Many other Wikipedias are available; some of the largest are listed below.
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