The arrival of solid particles from outside our solar system would present uswith an invaluable source of scientific information. Attempts to detect suchinterstellar particles among the meteors observed in Earth's atmosphere havealmost exclusively assumed that those particles moving above the Solar System'sescape speed -- particles on orbits hyperbolic with respect to the Sun-- wereprecisely the extrasolar particles being searched for. Here we show thathyperbolic particles can be generated entirely within the Solar System bygravitational scattering of interplanetary dust and meteoroids by the planets.These particles have necessarily short lifetimes as they quickly escape ourstar system; nonetheless some may arrive at Earth at speeds comparable to thoseexpected of interstellar meteoroids. Some of these are associated with theencounter of planets with the debris streams of individual comets; however,such encounters are relatively rare. The rates of occurrence ofhyperbolically-scattered sporadic meteors are also quite low. Only one of every10,000 optical meteors observed at Earth is expected to be such a locallygenerated hyperbolic and its heliocentric velocity is typically only a hundredmeters per second above the heliocentric escape velocity at Earth's orbit.Mercury and Venus are predicted to generate weak 'hyperbolic meteor showers':the restrictive geometry of scattering to our planet means that a radiant nearthe Sun from which hyperbolic meteors arrive at Earth should recur with theplanet's synodic period. However, though planetary scattering can producemeteoroids with speeds comparable to interstellar meteors and at fluxes nearcurrent upper limits for such events, the majority of this locally-generatedcomponent of hyperbolic meteoroids is just above the heliocentric escapevelocity and should be easily distinguishable from true interstellarmeteoroids.
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