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B Oumuamua asteroid discussion

  1. Dec 20, 2017 #21
  2. Dec 20, 2017 #22


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    Staff: Mentor

    Even with our current technology it would be trivial to spot signs of life on Earth from within the inner solar system. An image of the night side with sufficient contrast would work, a radio receiver would work, spectroscopy of Earth would see methane and oxygen as signs of life and couple of artificial compounds as signs of a civilization. We might be able to shut down the radio emissions, but not everything else.

    And we'll have much better technology long before we have the means to make interstellar trips, even at such a slow speed.

    If that would be an artificial object, "staying silent" wouldn't work.
  3. Dec 21, 2017 #23
    I also imagine that shooting a nuclear missile at it would be the equivalent of shooting an aircraft carrier with a bow and arrow.
  4. Dec 21, 2017 #24
  5. Dec 22, 2017 #25
    The asteroid is not that big. A nuclear weapon would most likely vaporize the 230 x 35 x 35 meter asteroid. Assuming it has an equivalent, or less, density than Earth. If the asteroid were to impact Earth and we could be assured that all the pieces of the asteroid after the nuclear blast were smaller than 20 meters in diameter, then that would be the way to go.

    A 20m diameter asteroid with 5.51g/cm3 density traveling at 50 km/s approaching the Earth at a 90° angle would begin to break up at an altitude of 48,900m (161,000 ft) and bursts into fragments at an altitude of 11,000m (36,200 ft.). The air blast would release 2.89 x 1016 Joules (6.89 MegaTons TNT) of energy. At a distance of 100 km the air blast will arrive approximately 5.08 minutes after the asteroid explodes in the atmosphere. The peak overpressure would be 987 Pa (0.14 psi) with a maximum wind velocity of 2.32 m/s (5.18mph) and have a sound intensity of 60 dB (heavy traffic). If you were directly beneath the air blast, the overpressure wave would arrive 47.2 seconds after the blast and peak at 14,700 Pa (2.09 psi) with a maximum wind velocity of 32.6 m/s (73 mph) and have a sound intensity of 83 dB (loud heavy traffic).

    Anything larger than ~20m (or denser than Earth) and there is a good possibility that it could reach the surface of the planet.
    Last edited: Dec 22, 2017
  6. Jan 11, 2018 #26


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    Aha! let me have a stab...
    The reference says that the initial velocity is closest to the local M Dwarf stars (Red Dwarfs) which are relatively common in the Galaxy.
    From Wikipedia - "Many red dwarfs are orbited by exoplanets, but large Jupiter-sized planets are comparatively rare." https://en.wikipedia.org/wiki/Red_dwarf#Planets
    So, abundant stars, with many small planets. How about two of these planets smash into each other and a fragment of metallic core blasts off towards us?

    (Oh, and the local aliens hop on board for the ride, hollow it out and live there, and watch us and giggle gleefully as we speculate about what it is. o0))
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