Thankfully, no one was injured during these events. However, the pieces of rock falling from the sky are not even the greatest concern regarding meteor impacts, Cooke said. For example, the Chelyabinsk meteor — an asteroid the size of a six-story building that entered Earth's atmosphere in February over Russia — broke apart 15 miles 24 km above the ground and generated a shock wave equivalent to a kiloton explosion, Cooke said.
It injured 1, people. Another major collision was the Tunguska meteorite, which was larger than Chelyabinsk and 10 times more energetic. The meteorite exploded over the Tunguska River on June 30, , and flattened , acres 2, square km of uninhabited forest. Because of its remote location, the event is an example of a meteorite that would have gone undetected had it not been so large, Cooke and Moorhead explained. Generally, astronomers are unable to predict meteorite impacts, largely because meteoroids traveling in outer space are too small to detect.
However, even large meteorite events that originate from asteroids, which can be tracked in space, are unpredictable. Fortunately, between 90 and 95 percent of meteors don't survive the fall through the Earth's atmosphere to produce meteorites, Moorhead explained.
This is because most meteorites are believed to come from comets, which are more fragile than asteroids. PHASE —. Tonight's Sky — Change location. US state, Canadian province, or country. Tonight's Sky — Select location. Tonight's Sky — Enter coordinates. UTC Offset:. Picture of the Day Image Galleries.
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Learn about the Moon in a great new book New book chronicles the space program. Dave's Universe Year of Pluto. Groups Why Join? Astronomy Day. The Complete Star Atlas. Most meteorites are pieces of asteroids, but others were born in more distant reaches of the solar system.
By David J. Eicher Published: Monday, July 1, About 50, years ago, an iron asteroid fragment the size of a football stadium struck the Arizona desert, producing the famous Barringer Meteor Crater. The Canyon Diablo meteorite was mostly vaporized, but scattered fragments like this one remain.
Bringing the universe to your door. Inclusions in the Allende meteorite, which fell in Mexico in , date back 4. This carbonaceous chondrite stone meteorite contains solidified drops of minerals from the ancient solar system.
A rare type of meteorite — stony-iron pallasites — contains a metallic matrix included with the mineral olivine. The tail actually has twin pieces, a gas tail and a dust tail , that can extend for millions of kilometers from the comet nucleus as it travels around the Sun. As the comet gets very close to the Sun, small pieces of dust, rock grains, and ice are left behind as a trail of meteoroids. Meteor showers occur when Earth passes through the trail of dust and gas left by a comet.
What are Meteorites Made Of? Scientists classify meteorites into three groups: stony meteorites, iron meteorites, and stony iron meteorites. What Do Meteorites Tell Us? Meteorites provide us with information about the processes and materials in our early solar system. The early solar system did not consist of a sun and planets. It was a spinning cloud of dust and hydrogen gas that was hotter in the center and cooler toward the edges. As the gas and dust began to come together, chondrules — tiny spheres of minerals containing silica — condensed.
These tiny spheres and dust gradually grew as other particles collided with them and became attached — a process called accretion. Some of the particles grew to the point that they were large enough to gravitationally attract other particles, and they accreted all the material in their path as they orbited the young Sun — some of these became our planets.
Other particles remained small, space rocks left behind after the planets formed. Accretion is a hot process; when a particle slams into another particle, its motion is converted to heat. The planets and some of the space rocks became so hot that they began to change, in some cases melting. Melting allowed the bodies to differentiate, with the heavier metals of iron and nickel sinking into a central core, and the lighter materials making a mantle and outer crust.
Not much when it is in space. Actually, it is the air in front of the meteoroid that heats up. The particle is traveling at speeds between 20 and 30 kilometers per second. It compresses the air in front, causing the air to get hot. The air is so hot it begins to glow — creating a meteor - the streak of light observed from Earth.
The intense heat also melts the outside of the meteoroid. However, for most rocks from space, even the short trip is sufficient to melt away much of it; a meter-sized meteoroid can be reduced to the size of a baseball.
Small meteoroids are vaporized completely. The outer melted part of the meteoroid solidifies, leaving a fusion crust — a thin dark glassy rind. The impact from a large meteoroid striking the surface may leave a crater — a circular depression. Large meteoroids leave craters about 10 times their size, although the size depends on how fast the meteoroid is moving, its angle of approach, and other factors. Meteor Crater was formed about 50, years ago when the meter-wide Canyon Diablo meteorite struck the ground, creating a kilometer-wide depression in Arizona.
Large impacts are rare now, but were much more common during the early history of our solar system when the space debris was being swept up. The surfaces of Mercury, the Moon, and Mars are covered with impact craters, most of which scientists believe formed during the first half billion years of solar system formation. Earth also has several impact craters on its surface, some quite large. One of the most famous — and destructive — impacts believed to have occurred took place about 65 million years ago.
This impact is thought to have triggered global fires and tsunamis and created a cloud of dust and water vapor that enveloped the Earth in a matter of days, resulting in fluctuating global climate changes. Where Do We Find Meteorites? Meteorites are fairly indiscriminate about where they land. They fall everywhere on Earth. Finding them is the challenge! A little more than two-thirds of Earth is covered by water; locating a meteorite on the deep sea floor is difficult, to say the least.
Meteorites also fall in unpopulated regions and places that are difficult to reach.
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