Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

B Does Modern Astronomy have a problem?

  1. Nov 6, 2017 #21

    ohwilleke

    User Avatar
    Gold Member

    It wasn't clear from the sentence structure what the parenthetical was referencing, and since 18.5 is close to the first three significant digits of the speed of light in miles per hour, I assumed it was referring to the speed of light and in error. But, your reading does make sense.
     
  2. Nov 6, 2017 #22

    jbriggs444

    User Avatar
    Science Advisor

    Is stellar abberation due to Earth's orbital speed actually relevant for parallax measurements? I would have imagined that measurements of parallax would be done by measuring deflection of the target object against a backdrop of other distant objects in photos taken 6 months apart. Stellar abberation from the Earth's motion would cancel out of such a measurement.
     
  3. Nov 6, 2017 #23

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    It depends on where your reference is and how you establish these references. Gaia for example has the near-term reference by the same telescope and one 60 degrees ahead/behind by the other telescope, and it has to correct for aberration with high precision.

    10-6 speed corresponds to up to 0.2 arcseconds deviation, and Gaia aims for ~10 microarcseconds precision for the brightest stars, a factor 20,000 smaller.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Does Modern Astronomy have a problem?
  1. Astronomy Problems: (Replies: 1)

Loading...