Weird Tracks

NASA's Mars Curiosity rover does not have built-in GPS. The only way to track Curiosity's whereabouts and how far it has traveled is by following the six explorer's wheel marks.

For this reason, engineers put holes in Curiosity's treads so that every time the wheels turn, they leave a unique imprint on Mars. Orbiters photograph the print and scientists can determine how far the rover has moved.

The track pattern spells out "JPL" in Morse code through a series of "dots" and "dashes." JPL is an acronym for NASA's Jet Propulsion Laboratory, the agency arm in charge of Curiosity.

Top Five Candies of 2010

Who says older is not better? Here are four oldies and one new one. All of them are still dominated by Mars and Hershey. Of the top ten candies, five are gum and five are chocolate.

1 M&Ms - Named after its two inventors, Forrest E. Mars Sr. and R. Bruce Murrie, M&Ms originally were packaged in a tube in 1941.
2 Reese's Pieces - H.B. Reese was a former dairy employee of Milton S. Hershey who began selling "penny cups" of peanut butter dipped in Hershey's chocolate in 1923. Hershey bought his company 40 years later.
3 Hershey's - Milton S. Hershey began making his milk-chocolate bar in 1900.
4 Snickers - Snickers has been around since 1930 and was the Mars family's second product. It was named after their favorite horse.
5 - Orbit Gum - Orbit hit the U.S. market in 2001, but the brand goes back in Europe to 1976, when it was introduced as Wrigley's first sugarless gum. Mars took over Wrigley in 2009.