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    Re: A question for the geodisists
    From: Frank Reed
    Date: 2013 Dec 18, 23:40 -0800

    Alex, you wrote:
    "Well, we know examples of complete disappearance of islands in the Pacific (Tabor=Maria-Theresa island and reef Ernest Legouve are some examples:-) So why should we be so surprised if an island is shifting a little?"


    Your reference to your favorite vanishing islands (calling back to your earliest messages in 2004) reminds me of the Gaia astrometry mission which will be launching aboard a Russian Soyuz rocket from Kourou in French Guiana about two hours from now. The Gaia spacecraft is fundamentally an angle-measuring instrument, in effect a spectacularly accurate space-based sextant. It will measure the parallaxes of a BILLION stars in the Milky Way over the course of the next ten years, and those measurements will yield yet another revolution in modern astronomy. Here's an article describing the Gaia mission and its amazing angular observations: http://www.skyandtelescope.com/news/home/Gaia-to-Pinpoint-a-Billion-Stars.html.

    With any luck, right about now, some readers of this message are thinking, 'how the heck do we go from a reference to a disappearing island in the Pacific to a spacecraft launching in two hours from South America?!?' Good question...

    First, you need to know that the lost island "Tabor" or "Maria Theresa" was adopted by Jules Verne as the location of Captain Nemo's "Mysterious Island". That alone should get you halfway there since, after all, what could be more "Jules Verne" than a European astrometric spacecraft launching from French Guiana on a Russian rocket? Truth is stranger than fiction.

    But the real sequence that connected these things up for me personally is a little more "warped" ...as in "warp speed". It goes like this: Jules Verne and Maria Theresa Island made me think of Captain Nemo. Captain Nemo made me think of the classic Disney movie "20,000 Leagues Under the Sea". In the Disney movie there is a penal colony island named "Rura Penthe". Ok so far? Now we make a spacetime jump: in the movie "Star Trek VI", Kirk and McCoy are sentenced to the Klingon prison asteroid --which is named "Rura Penthe" as a little homage to that earlier movie. And "Star Trek" is the first place that I can remember hearing the word "parsec" which is defined as the distance at which a star would have an annular parallax of one arcsecond. And that brings us back to the Gaia mission which will measure stellar parallaxes at a level of a few dozen micro-arcseconds. And now it all makes sense, right?! From a non-existent island in the South Pacific back in the 19th century to a rocket launch in French Guiana ...all in seven easy steps.

    For those of you awake, either because it's daylight on your side of the Earth, or because you're a night owl like me, you can watch the launch of Gaia live, if the weather cooperates, here:


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