From 1976 to 1991, some people thought these odd formations were the work of aliens (which they probably are), but some are intricate fakes. Who came forward - Making crop circles - Lightning in slow motion - Tesla coils play Mario
X-ray technology shows how Leonardo da Vinci achieved a mystifying quality in his paintings. Layers thinner than hair - Looted art at Colosseum
World endures hottest year on record
Weather analysis blames El NiƱo for abnormally warm temperatures and droughts. What may cool us down - How people chill out - Europe heat melts roads
Droid X vs. BlackBerry vs. iPhone 4
These phones may be best-in-class, but each comes with its own drawbacks. One is "notoriously clunky" - Droid X already sold out
Skin-lightening Facebook app causes stir
A new ad campaign encourages men in India to whiten their profile photos. Long-running, racially charged issue - Indian caste system - Summer skin FAQ