[组图]The Tunguska Fireball

1908年6月30日在西伯利亚中部的Tunguska高原发生了大爆炸，究竟是什么原因导致了这次大爆炸？

At night, you can sometimes see a meteor① if there are no bright lights nearby. We call it a“falling star.” Most meteors die as they enter the earth's atmosphere. The friction of the meteors passing through the atmosphere burns them up, even though they are made of rock and metal.

When a meteor hits the earth, it is then called a meteorite②. Most are very small. However, occasionally in the past, large meteorites hit the earth and made huge craters. There is a one in Australia and another in Arizona. They are both thousands of years old.

Was a meteorite the cause of the explosion in Tunguska, in central Siberia, in 1908? On June 30 of that year, the inhabitants of the lonely Tungus plateau③ saw a very bright light in the sky. Seconds later, they heard a explosion. For years afterwards, they talked about the brightness of the sky that night.

Tunguska is so remote that it was twenty years before scientists traveled there to look for the cause of the explosion. Even after all that time, the area was still completely destroyed. Trees were black from the explosion. At first, scientists thought a meteorite was the cause. Others said it might be a huge ball of fire. Newspapers printed articles on the fireball of Tunguska. Some journalists went further. They wrote about the crash landing of an alien spaceship.

Years have passed since then, but even today no one can fully explain the Tunguska explosion. One recent theory is that a meteor exploded just before it hit the earth's surface. That is why there was no crater like those in Arizona and Australia. However, no one knows for certain, and the explosion in Tunguska remains a mystery.

Notes:①meteor /`mi:ti/ n.流星

②meteorite /`mi:tirait/ n.陨星；陨石；陨铁

③plateau /`pltu/n.高原

by Patricia Ackert, Linda Lee and Barbara Bushby