Target Earth: Disasters from Space
The Earth has a very long history with celestial objects falling from space. Thousands of meteorites entering the atmosphere every year burn and disappear in the air before they can fall to the earth. The ones that are too big to burn in the air hit the ground and open craters of various sizes. There are many craters on Earth, but some of them are very difficult to find. Some have only been discovered in recent years thanks to satellite photographs taken very far away.
The Barringer Skystone Crater in Arizona is about 1 km in diameter and 200 m deep. It was created by a meteorite weighing more than 100,000 tons, some 50,000 years ago. When meteors hit the ground, their speed is about 45,000 kilometers per hour. This speed is enough to turn into a fireball and evaporate when it forms a crater.
From the sky
In 1954, Anne Hodges of America became the first known man to be shot by a meteorite. He was asleep at home when the meteorite hit, and he survived the accident with a few bruises.
The Manicouagan Crater in Eastern Canada was created by a 5 km-wide meteorite that hit Earth 200 million years ago. Today, the crater is used as an annular dam. Being filled with water makes it easier to see from space. The impact of the crater was so strong that it took about a thousand years for the crater to cool down.
MYSTERY OF CYPRUS
In June 1908, a huge explosion occurred in the Tunguska River region of Siberia. Eyewitnesses said that a fireball had fallen from the sky and that the forests in the area of 3,000 square kilometers were flat from the point of explosion. Scientists believe that the explosion was due to a large meteorite falling in the air as it landed on Earth.
Unlike Earth, the surface of the Moon is not eroded by rains and winds. Most craters were formed billions of years ago, and the larger ones contain smaller craters. The largest crater of the Moon is near the south pole and has a diameter of 2300 kilometers, almost half the width of the Moon. This crater is probably not a head-on collision, but a side-impact crash.
METEORITES FROM MARS
Few of the meteorites that have fallen to Earth originate from the planet Mars. Antarctica in this photograph was found in the ice sheet. (Antarctica is the perfect place for meteorite hunting. Dark objects on ice can be easily found.) Martian meteorites attract scientists because some of the chemicals found on Earth’s creatures have been identified.