BUILDING PLANETS

PIECES OF ASTEROIDS AND PLANETS THAT FALL TO EARTH AS METEORITES REVEAL THE PROCESSES AT WORK DEEP INSIDE PLANETS-INCLUDING OUR OWN.

THE FARMLAND NEAR BRENHAM, KANSAS, is flat and almost entirely free of rocks-yet farmers in the 1880s occasionally bent their plows on mysterious metallic objects. Homesteader Eliza Kimberly noticed that the odd black rocks resembled a meteorite she had seen as a schoolgirl in Iowa. Despite teasing from her husband and neighbors, she collected a large pile of the "iron rocks," and after five years of letter-writing she convinced a scientist to look at them. They were indeed meteorites.

The remarkable Brenham meteorite fragments contain gemlike olivine crystals embedded in an iron-nickel alloy. Billions of years ago, this rock and iron mixture formed when a large asteroid melted and separated into an iron core and a rocky crust. Meteorites that come from the deep interiors of such asteroids provide tantalizing clues about the interior of Earth and other planets.

METEORITES ON THE MOVE

The Brenham meteorite scattered more than three tons of meteorite fragments in the vicinity of Brenham, Kansas. Pieces of the Brenham meteorite have also been found up to 1,500 kilometers (1,000 miles) away-transported by Native American traders and buried in mounds by the Hopewell people more than 1,500 years ago. Some pieces were pounded into iron knives, ear ornaments, chisels, buttons and beads.

For thousands of years, meteorites were the primary source of iron metal for peoples around the world. All natural iron rusts, or oxidizes. But only meteoritic iron is mixed with nickel, forming a steel alloy that is extremely strong and rust-resistant.

SEARCHING FOR METEORITES

The world's greatest meteorite hunter was Harvey H. Nininger (1887-1986). To track down these rare objects, Nininger went door to door in areas where meteorites had been discovered, urging men, women and even children to keep an eye out for further specimens. He gave lectures in stores, bars and on the street, educating entire communities about the science of meteorites. More meteorites were discovered in places where he visited than anywhere else in America. Through gifts and purchases, Nininger amassed a personal collection so large he started his own museum.

In the 1920s, Harvey Nininger visited the Kimberly farm in Brenham, Kansas, where more than a ton of meteorites had been discovered. Examining a large oval depression-previously thought to be just a buffalo wallow-he concluded it was actually a crater formed by the impact of a large meteorite. His 1933 excavation, performed with the help of his family (above), proved him correct. The crater formed by the Brenham meteorite was one of the first impact craters discovered in the United States and one of Nininger's greatest successes.