Meteorites are the stars of this show

NEW YORK, Oct. 3 (UPI) -- The American Museum of Natural History's matchless collection of meteorites has been freshly showcased in a spectacular circular hall designed to convey the latest research on these visitors from space and what they tell us about the origins of the earth, the sun, and the 4.56 billion-year history of our solar system.

The Ross Hall of Meteorites, first opened in 1981, has been reconfigured and fitted out with interactive computer stations and the hall's first diorama and video theater in the course of a six-month renovation. The dramatically illuminated hall is now centered on one of the museum's rarest treasures, the 34-ton Ahnighito meterorite, the largest on display in any museum in the world.

To support the weight of Ahnighito, the museum floor at the point of its display has been reinforced with steel support posts extending down into Manhattan's bedrock.

There are 130 specimens composed of either iron or stone on display in the hall, many of which can be touched, but the Ahnighito - shaped like a sinister dinosaur skull - pulls at the visitor like an iron magnet from its raised, spotlighted central platform. It was brought to the American Museum of Natural History in 1897 by Arctic explorer Robert E. Peary from Cape York, Greenland, where it landed thousands of years ago along with two much smaller meteorites, The Dog and The Woman, also on view.

Ahnighito (the word means "tent" in the Inuit language) is composed of iron with a unique pattern of crystals never found in earthly iron and comes from the heart of an asteroid. There is evidence in the case of The Woman that it was used as a source of iron by Inuit Indians. Ancient man was the first to use meteor iron in what is now known as the Iron Age, having learned that it was easier to chip away at meteorites than to dig for the metal needed to fashion durable, sharp weapons and tools.

Asteroids and comets are the most common foreign objects to impact the earth, usually in the form of fireballs that have entered the earth's atmosphere at speeds of thousands of miles an hour and caused deep craters in the earth's surface. One of the displays new to Ross Hall is a scale model of the Barringer or Meteor Crater in northern Arizona, exhibited in the form of a diorama along with two pieces of the meteorite.

Researched by mining engineer Daniel M. Barringer, Meteor Crater was important in convincing scientists a century ago that craters on the moon and other planets were caused by meteorite impacts rather than volcanic eruptions as had long been believed.

Meteor Crater was created 50,000 years ago by an 80-foot-diameter iron meteorite that blasted a cavity three-quarters of a mile wide, the best preserved crater on earth. It is one of about 200 meteorite craters that have been identified on the earth's surface to date, although countless others probably crashed on our planet.

The oldest objects in the exhibit are microscopic diamond grains -- part of the original dust from which the universe was formed -- found in fragments from the 4.5 million-year-old Allende meteorite that exploded over northern New Mexico in 1959. The diamond dust was formed by supernova explosions some 10 billion years ago before being absorbed into the meteorite.

Although many of the Museum of Natural History exhibits are accompanied by wall and computer texts written simply enough for a grade school student to understand, information provided in Ross Hall is mostly at the adult level. But there is much to fascinate children, and a seven-minute video narrated by astronaut Sally Ride explains meteorites and their relation to familiar objects in our solar system in layman's language.

One of the fascinating things about meteorites is that they still exist and are a potential impact hazard to the earth. The show explains that greatest source of asteroids, which are actually mini-planets, is a belt between Jupiter and Mars where Jupiter's gravitational pull keeps them from merging into full-fledged planets.

The earth's moon probably resulted from a glancing but titanic collision of the young earth and a planet the size of Mars that was vaporized and may have become part of both the earth and the moon. There are three rocks recovered from the moon by Apollo astronauts in the show and five rare meteorites identified as coming from Mars, the only samples of that planet on earth.

It wasn't until 1803 that it was generally accepted that meteorites arriving on earth as spectacular fireballs actually were extraterrestrial in origin. In that year one exploded over L'Aigle in Normandy and was witnessed by many people including French officials who attested to its having come from the sky. The first recorded American fireball exploded above Weston, Conn., in 1807, and a small fragment of it is in the show.

Another little-known fact gleaned from this show: Every day about 100 tons of extra-terrestrial material rain onto earth, most in the form of grains of dust that float gently downward and land undetected. The U.S. spacecraft Stardust, launched in 1999, is currently on the other side of the sun from earth collecting samples of this mysterious material.