5 comments

  • astro123 37 days ago

    I highly recommend these books by Alan Hirshfeld [1][2]. The first is about the discovery of parallax, and the instrument that was used to do this in 1838 was built by Fraunhofer. The precision of the instrument required to do this is incredible - the movement of a star due to parallax is, over the course of a year, about a fifth of the angular size of jupiter's great red spot. Unless you've been lucky enough to look through a fairly big telescope, you've probably never seen the great red spot and two centuries ago Bessel (using Franhofer's instrument) was able to detect a change in position of a small fraction of this.

    The second book is about the technological developments of ~1850-1920 (cameras, spectroscopes, big telescopes) and is also really interesting. Fraunhofer also makes an appearance here - he was one of the first people to measure the absorption spectrum of the sun. These absorption features are still called Fraunhofer lines [3]. Later Kirchhoff (of the circuit laws) and Bunsen (of the burner) worked out what caused these.

    The personal histories of all these people are also really cool, and these books discuss the people as much as the science/tech. It's amazing for how many people a small bit of luck was needed (or in Fraunhofer's case with the house collapsing -> meeting the elector, a big bit of luck)!

    [1] https://www.amazon.com/Parallax-Measure-Alan-W-Hirshfeld/dp/... [2] https://www.amazon.com/Starlight-Detectives-Astronomers-Ecce... [3] https://en.wikipedia.org/wiki/Fraunhofer_lines

    • mymythisisthis 36 days ago

      https://librivox.org/edison-his-life-by-dyer-and-martin/ Thomas Edison

      "The attitude thus disclosed toward Mr. Edison's work was never changed, except that admiration grew as fresh inventions were brought forward. To the day of his death Lord Kelvin remained on terms of warmest friendship with his American co-laborer, with whose genius he thus first became acquainted at Philadelphia in the environment of Franklin."

    • basementcat 37 days ago

      This is the person of which the Fraunhofer Institute is named in honor. Among other things, they also developed the MP3 coding format.

      https://en.wikipedia.org/wiki/Fraunhofer_Society

      • taejo 37 days ago

        Minor nitpick: the Fraunhofer Society is an organization with multiple Institutes across Germany (plus some Centers outside Germany), each working on different areas of applied science. MP3 was developed at the Fraunhofer Institute for Telecommunications.

        • 4k05 37 days ago

          Since we are nitpicking...mp3 was invented by the Fraunhofer Institute for Integrated Circuits, the Fraunhofer Institute for Telecommunications is a relatively new addition to the Fraunhofer Society, before 2003 it was called Heinirch Herz Institute. If I recall correctly, HHI was instrumental in developing the H.256 Video Coding Standard

          • taejo 36 days ago

            That's what I get for just skimming the Wikipedia article. Thanks.

        • amelius 37 days ago

          > they also developed the MP3 coding format.

          Why did they name their format after the litigous MPEG group, while in fact it was (afaik) an open format?

        • dang 37 days ago
          • sxcurry 37 days ago

            Interesting article. I just started doing some amateur spectroscopy with an ALPY spectroscope. Seeing the absorption and emission lines of distant stars is fascinating.

            • dylan604 37 days ago

              I've always wanted to do this myself just so I can see how one isolates a single star in view to get the reading.

            • colinmegill 37 days ago

              Cosmos dedicated an episode to him