Phigla

Dear Gfamily, Thanks for your reply, it clarify a little bit the Heliometer principle for parallax measurement made by Bessel. But is sill remaining a bit nebulous Have a nice week

Good morning, I just registered on this website. As said in my presentation since recently I'm passionate about the history of the Astronomy...It's my first question I read that the first parallax measurement was made by , Friedrich Bessel in In 1838 using a Fraunhofer heliometer. Looking on the internet this topic the only thing I read is that is a refracting telescope with the lens cut in two, one half is fixed, the other half mobile with a micrometer. At the origin it was made for sun diameter measurement and Bessel used it for parallax measurement If a member can tell me more about the principle and how it's work I will be very happy, because I do not find any info on the net. Thanks in advance

Good morning, I'm retired in China, I'm 72 and coming from Europe. Since few months I'm interested about the history of Astronomy since Copernic till the 20th century I registered on this forum to discuss this topic and mainly the astronomical instruments and of course I will have question Hello to everybody Have a nice day