New Horizons shoots a movie

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In anticipation of its fly of Pluto next year, the New Horizon spacecraft has produced a 12 frame movie showing Pluto’s moon Charon circling the planet.



  • DK Williams

    What I find really cool about this movie is that you can see Pluto wobble in response to the gravitational tug of Charon as the latter orbits around its host planet. (I refuse to add “minor.) This is readily apparent because the mass of Charon is substantial relative to Pluto. It’s one method (wobble) used to detect extrasolar planets, although I believe the light dimming method is preferred. Bob, please correct me if I’m wrong.

  • Edward

    A couple of decades ago, before extrasolar planets were being discovered, I went to a talk about methods to find them. Each method had its disadvantages.

    Occultation (dimming) required that the target solar system (or at least the planet’s orbital plane) be edge-on to our line of sight. Thus, I was surprised at the large number that Kepler seems to have found.

    Doppler (wobble) would likely find many planets, but their mass would be difficult to determine, as the wobble would be reduced due to the angle of the orbital plane relative to the line of sight. Thus, all that could be determined was a planet’s minimum possible mass.

    Direct observation would have been the preferred method, but the range for distinguishing a planet from its star was short, limiting this method only for nearby stars.

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