Meteors

Meteors are streaks of light formed when chunks of metallic or stony matter known as meteoroids enter the Earth's atmosphere at high speeds from space. Most meteoroids disintegrate before reaching Earth. Those that do strike our planet are called meteorites.

Image at right: Meteor (courtesy of NASA).

Millions of meteors occur in the Earth's atmosphere each day. Larger meteoroids that cause these meteors are usually pieces of asteroids shattered by collisions in the asteroid belt. Smaller particles are mostly rock and dust shed by passing comets. Other sources of meteoroids have come from impacts on the Moon or Mars.

Scientists have discovered over 120 impact craters and basins on Earth. Barringer Meteorite Crater in Arizona is about 4,180 feet across and 570 feet deep. It was formed about 50,000 years ago by an iron meteor.

Features

: Moon Meteorite (Courtesy of NASA Johnson Space Center)

There are three basic kinds of meteorites: stone, iron, and stony-iron. Meteorites feel heavier than ordinary Earth rocks. A freshly fallen stone meteorite can look much like a charcoal briquette!

Once a meteorite is on the ground, it starts to weather causing oxidation of its crust and turning it from black to brown. Many small meteorites have been found in Antarctica and could provide clues regarding the material that formed the planets.

Learn more about the features of meteors on NASA's Solar System Exploration website.

Missions

: Logo of the U.S. Antarctic Program<br /> (Courtesy Don Pettit - NASA)

Meteorites can be pieces of asteroids that provide scientists with clues about the early Solar System. NASA's Dawn mission to the asteroid belt will provide us with more insight about what meteorites have been showing us. Launched in September 2007, Dawn will study Ceres and Vesta in the vast asteroid belt between Mars and Jupiter.

The Antarctic Search for Meteorites (ANSMET) program is currently collecting samples of meteorites which they send to Johnson Space Station for analyzing. They have recovered over 10,000 meteorite specimens. They are always looking for adventurous volunteers to join their team and spend five to seven weeks on an ice field in Antarctica.

Learn more about the ANSMET program.

Myths, Stories, and More

: Meteor Outburst<br /> (S. Molau and P. Jenniskens, NASA Ames Research Center)

Many ancient people such as the Greeks and Romans thought thunder, lightning, and meteors were caused by the same god. Some Native American tribes believed meteors were fragments of lunar material and referred to them as "children of the moon."

In legends of central Asia, meteors were fire serpents who traveled across they sky, sometimes bringing treasure and at other times causing problems. Various cultures have viewed meteors as something either very good or something very bad.

Discover more about meteors and folklore at StarrySkies.com.

Earth Matters

: Meteorite Hunters<br /> (Courtesy of NASA Johnson Space Center)

When Earth passes through the orbit of a comet, the leftover debris bombards Earth and burns up in our atmosphere, creating a meteor shower. Some meteor showers occur regularly, including the Perseid meteor shower that occurs every August when the Earth passes through the orbit of comet Swift-Tuttle.

You don't need a telescope to see the Perseid meteor shower! Just pick a clear night in mid-August to enjoy the show. The Perseid meteor shower happens every year and will peak August 12 and 13 in 2009. If you're in the Chicagoland area during the month of August, join the Adler at Cantigny Park to observe this remarkable meteor shower. If you could trace back the paths of the meteors you see, you would notice the paths trace back to a region in the direction of the constellation Perseus. This is why the shower is called the "Perseid meteor shower." The meteors aren't really originating from this constellation, but instead are from left-over debris from the Swift-Tuttle comet. You can view the same effect happening with the Geminid meteor shower in this photo from Geology.com.

Meteorites are very important to scientists, who analyze them to help us learn more about Earth and the Solar System. Beside the samples brought back to Earth by the Apollo (NASA) and Luna (Soviet Union) missions, meteorites are the only pieces of off-Earth materials we can study directly.

The Vatican Meteorite collection is one of the largest in the world. The curator of the Vatican Meteorite Collection, Br. Guy Consolmagno, has given many talks at the Adler Planetarium, including ones that address the history of Galileo and the Catholic Church.

Find out more about Earth and meteor connections from Nine Planets.