Risk of collision of the Earth with an asteroid — the question is not idle, the more that the planet can be seen from the impact craters of Skywalker, against which the recent hero of the world's media? Chelyabinsk meteorite? or Siberian mysterious visitor? Tunguska meteorite? show "the kids."
Thus, 66 million years ago an asteroid, who met with the surface of the earth in the Yucatan peninsula, put an end to the era of the dinosaurs, leaving a crater with a diameter of more than 180 kilometers.
However, a recent survey of Australian researchers led to a new incredible discovery: at least 298 million years ago in the Green Continent asteroid crashed even larger.
"The dust and greenhouse gases, the powerful seismic shock and a gigantic explosion — the consequences of the disaster affecting the entire planet — said Professor Andrew Glikson (Andrew Glikson) from the Australian National University. — Asteroid permanently changed the environment on Earth, for example, greenhouse gases remain in the the atmosphere for thousands of years. "
In an article published in the journal Tectonophysics, Glikson and his colleagues report that traces of ancient metamorphic collision were found at a depth of four kilometers in the state of South Australia.
Using three-dimensional optical microscope, scanning electron microscope and transmission electron microscope, the experts analyzed the particles of quartz extracted from the pre-drilled holes in the ground, and explore numerous seismic anomaly.
The diameter of the space wanderer of 10 to 20 kilometers, and it affected the surface area is approximately 30 square kilometers. Because dating is not exactly done yet, scientists indicate only possible period of a meteorite (298-360 million years ago), that allows us to connect with the consequences of a collision Devonian mass extinction.
It is noteworthy that the latter is considered to be the culprit another meteor, also fell in Australia, but in the western part. About him on impact craters Woodley.
Experts believe that two of the crater (now discovered and old) may be linked. "Actually, asteroids may appear in groups of several large projects — says Glikson. — In cases where the simultaneous fall are traces of two or more meteorites, we can assume that they are part of a single asteroid before, sprawled on the approach under the influence of gravity Earth-Moon system. "
Category: Astronomy and Space