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The Sutter's Mill meteorite is a carbonaceous chondrite which entered the Earth's atmosphere and broke up at about 07:51 Pacific time on April 22, 2012.〔〔 The name comes from the Sutter's Mill, the California Gold Rush site near which some pieces were recovered.〔〔 This was the largest meteoroid impact over land since asteroid 2008 TC3. Meteor astronomer Peter Jenniskens assigned SM numbers to each meteorite, with the documented find location preserving information about where a given meteorite was located in the impacting meteoroid. As of May 2014, 79 fragments have been publicly documented with a find location. The largest (SM53) weighs 205 grams,〔〔 and the second largest (SM50) weighs 42 grams.〔 The meteorite was found to contain some of the oldest material in the Solar System.〔http://www.sciencenews.org/view/generic/id/347199/description/California_meteorite_a_scientific_gold_mine〕〔http://www.nature.com/news/us-meteorite-was-fastest-on-record-1.12095〕〔http://www.businessinsider.com/one-of-the-fastest-rarest-meteorites-recovered-in-californias-gold-county-2012-12〕 Two 10-micron diamond grains (xenoliths) were found in the meteorite recovered before rain fell.〔 In primitive meteorites like Sutter's Mill, some grains survive from what existed in the cloud of gas, dust and ices that formed the Solar System. ==History== During the 2012 Lyrids meteor shower, a bolide and sonic boom rattled buildings in California and Nevada in daylight conditions in the early morning at 07:51 PDT on 22 April 2012.〔 The bolide air burst was caused by a random meteoroid, not a member of the Lyrids shower.〔 The bolide was so bright that witnesses were seeing spots afterward.〔 The falling meteorites were detected by weather radar over an area centered on the Sutter's Mill site in Coloma, between Auburn, California, and Placerville, California.〔 Robert Ward found a small CM chondrite fragment in the Henningsen Lotus Park just west of Coloma, CA on 24 April 2012.〔 Later that day, Peter Jenniskens found a crushed 4 g meteorite in the parking lot of that same park and Brien Cook found a 5 g meteorite off Petersen Road in Lotus. These were the only meteorites found before rain hit the area on 25 April. On 1 May 2012, the James W. Marshall Gold Discovery State Historic Park's Ranger Suzie Matin discovered two pieces of the meteorite (SM14 @ 11.5 grams) in her front yard. The park contains what is now known as Sutter's Mill (site).〔 On 3 May 2012 scientists with the Ames Research Center and the SETI Institute utilized an airship to search the strewn field for the impact scars of kg-sized meteorites, but it is now understood that the high entry speed prevented the survival of meteorites as large as found in the Murchison meteorite fall.〔 Ground-based searches resulted in the additional recovery of two pristinely collected meteorites (SM12 and SM67) for scientific study. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sutter's Mill meteorite」の詳細全文を読む スポンサード リンク
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