Space Rocks In Australia: How to Find a Meteorite
January 13, 2016
On Nov. 27, 2015, a rock ended a space journey that had lasted for billions of years when it collided with Earth. This itself is not unusual, but this rock happened to be large enough to survive the fall to Earth, and it fell in an area monitored by a network of cameras created to record exactly these types of events.
A meteor is a streak of light that appears in the sky. Meteors appear when pieces of matter enter Earth’s atmosphere from space at high speeds. Such a piece of matter, while in space, is called a meteoroid. Many meteoroids are chunks broken off from larger orbiting bodies called asteroids. As the meteoroid flies through Earth’s atmosphere, it is heated so that it glows, creating a shining trail of hot gases. Most meteoroids that cause visible meteors are smaller than a pebble and disintegrate in the atmosphere. Some meteoroids are larger or made of stronger materials, however, and reach Earth’s surface. These meteoroids are called meteorites once they are on Earth’s surface.
Meteorites are “leftovers” from the formation of our solar system some 4.5 billion years ago. Scientists can learn much about the solar system’s origin and makeup by studying them. But most meteorites are never found. Their landings go unnoticed after they crash on Earth and they end up buried in soil or sediment or at the bottom of the ocean. Meteorites that are found are usually discovered long after they have landed, with few or no clues as to where in space they came from.
When the meteorite struck Earth on November 27th, however, it was spotted by the Desert Fireball Network (DFN), a grid of 32 cameras pointed at the sky in Western Australia and South Australia. These cameras are situated on the Nullarbor Plain, a dry, desert region where few people live, so there is little light pollution (the glow from streetlights and other artificial lights that is found in cities). This light pollution, called skyglow, would obscure the cameras’ views of the night sky. The Nullabor Plain also has other features that make it a good place to retrieve meteorites. The plain has very little plant growth to obscure features left by a meteorite’s impact with Earth’s surface, and the infrequent rains allow craters to be preserved for many months.
Using the data obtained by the DFN, scientists from Curtin University of Technology in Perth estimated the size and landing site of the meteorite. After days of searching, they found the 3.5-pound (1.6-kilogram) rock under several inches, or centimeters, of mud in the dry bed of Lake Eyre in South Australia, just hours before rains would have washed the impact features away. The researchers will now be able to combine data on the path the meteorite took to Earth with its composition to determine its orbit and parent asteroid. This information will help to reveal conditions in the early solar system.
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