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Post Info TOPIC: Asteroid seismology


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RE: Asteroid seismology
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En général, la surface des petits corps sans atmosphère du système solaire est vieillie par les impacts de micrométéorites, le vent solaire et les rayons cosmiques. Les astéroïdes qui croisent l'orbite de la Terre par contre, nous apparaissent avec une surface rajeunie, différente de ceux de la ceinture principale. Une équipe franco-américaine, dont des chercheurs de l'Observatoire de Paris, émettent l'hypothèse que les ondes sismiques induites par le passage proche de la Terre sont capables de réarranger les roches et ainsi rajeunir la surface de l'astéroïde.
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We already know that asteroid impacts can cause cataclysms on Earth - now it seems that Earth can hit back. Close encounters with our planet appear to shake up the structure of some asteroids.
The idea explains an old puzzle. Most asteroids are stained dark red by the relentless bombardment of space particles. But some asteroids that stray into the inner solar system are paler, like the interior of meteorites.
One theory was that they have suffered collisions, exposing fresh rock on their surfaces. Now researchers led by Richard Binzel of MIT has confirmed a rival theory.

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New research suggests that near-Earth encounters can 'shake' asteroids

For decades, astronomers have analysed the impact that asteroids could have on Earth. New research examines the opposite scenario: that Earth has considerable influence on asteroids -- and from a distance much larger than previously thought. The finding helps answer an elusive, decades-long question about where most meteorites come from before they fall to Earth and also opens the door to a new field study of asteroid seismology.
By analysing telescopic measurements of near-Earth asteroids (NEAs), or asteroids that come within 30 million miles of Earth, MIT Professor of Planetary Science Richard Binzel has determined that if an NEA travels within a certain range of Earth, roughly one-quarter of the distance between Earth and the moon, it can experience a "seismic shake" strong enough to bring fresh material called "regolith" to its surface.

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