Inthesummerof1978anEnglishmannamedStevenwasdrivinghistractorthroughafieldofwheatwhenhediscoveredsomethingstrange.Someofhiswheatwaslyingontheground.Theflattenedwheatformed(形成)acircleaboutsixmetersacross.Aroundthiscirclewerefoursmallercirclesofflattenedwheat.

　Threeyearslaterafarmerwholivednearbydiscoveredalmostthesamecirclesinoneofhisfields.Thesecircleswerelarger—nearly15metersacross.Thatsameyear,anotherEnglishfarmerdiscoveredthreecirclesofflattenedwheatonhisland—onelargecirclebetweentwosmallcircles.Duringthefollowingyears,farmersinEnglandfoundcirclesintheirfieldsmoreandmoreoften.

　Thecirclesarecalled“cropcircles”becausetheyusuallyappearinfieldsofwheatorcorn.Thewheatinthecirclesliesonthegroundbutisneverbroken;itkeepsongrowing,andthefarmerscanlaterharvestit.Farmersalwaysdiscoverthecropcirclesinthemorning,sothecirclesprobablyformatnight.TheyappearonlyinthemonthsfromMaytoSeptember.Whatcausesthecropcircles?

　Atfirst,peoplethoughtthatsomekidsweremakingthemasajoke,orthatfarmersweremakingthemtoattracttourists.(Infact,in1991,twomensaidtheymadethecirclesthemselves,butmanyscientistsdon’tbelievethem.)Peopletriedtocopythem:Theytriedtomakecirclesexactlyliketheonesthefarmershadfound.Theycouldn’tdoit.Theycouldn’tenterafieldofwheatwithoutleavingtracks,andtheycouldn’tflattenthewheatwithoutbreakingit.

　Severaltimespeoplereportedseeingstrangerobjectsnearthefieldswherecropcircleslaterappeared.Manypeoplebelievethatthesecropcirclesarethemessagessentbylivingthingsfromouterspace(外层空间)orthemarksleftbytheirspaceships.

　Scientistswhohavestudiedthecropcirclestrytofindoutwhatcausesthem.Inthesummerof1990somescientistsspentthreeweeksinthepartofEnglandwheremanycircleshaveappeared.Theyhadallthelatesthigh-techequipment(最新高科技设备).Theequipment—worth1.8milliondollars—gotnothing.Butonenight,asthescientistswerewatchingafield,cropcirclesformedinthefieldbehindthem,whichwerequitedifferentfromtheothers.Thescientistshadneitherseennorheardanything.

　WhenStevendisco