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  2. Parallax in astronomy - Wikipedia

    en.wikipedia.org/wiki/Parallax_in_astronomy

    The motion of the Sun through space provides a longer baseline that will increase the accuracy of parallax measurements, known as secular parallax. For stars in the Milky Way disk, this corresponds to a mean baseline of 4 AU per year. For halo stars the baseline is 40 AU per year. After several decades, the baseline can be orders of magnitude ...

  3. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    The motion of the Sun through space provides a longer baseline of the parallax triangle that will increase the accuracy of parallax measurements, known as secular parallax. For stars in the Milky Way disk, this corresponds to a mean baseline of 4 AU per year, while for halo stars the baseline is 40 AU per year. After several decades, the ...

  4. Parallax - Wikipedia

    en.wikipedia.org/wiki/Parallax

    The motion of the Sun through space provides a longer baseline of the parallax triangle that will increase the accuracy of parallax measurements, known as secular parallax. For stars in the Milky Way disk, this corresponds to a mean baseline of 4 AU per year, while for halo stars the baseline is 40 AU per year. After several decades, the ...

  5. Stellar parallax - Wikipedia

    en.wikipedia.org/wiki/Stellar_parallax

    Stellar parallax is so difficult to detect that its existence was the subject of much debate in astronomy for hundreds of years. Thomas Henderson, Friedrich Georg Wilhelm von Struve, and Friedrich Bessel made the first successful parallax measurements in 1832–1838, for the stars Alpha Centauri, Vega, and 61 Cygni.

  6. Aberration (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Aberration_(astronomy)

    The other, observable, part is an acceleration toward the galactic center of approximately 2.5 × 10 −10 m/s 2, which yields a change of aberration of about 5 μas/yr. [15] Highly precise measurements extending over several years can observe this change in secular aberration, often called the secular aberration drift or the acceleration of ...

  7. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    The 1976 definition of the astronomical unit was incomplete because it did not specify the frame of reference in which to apply the measurement, but proved practical for the calculation of ephemerides: a fuller definition that is consistent with general relativity was proposed, [26] and "vigorous debate" ensued [27] until August 2012 when the ...

  8. Hipparcos - Wikipedia

    en.wikipedia.org/wiki/Hipparcos

    The resulting effect of secular or perspective acceleration is the interpretation of a transverse acceleration actually arising from a purely linear space velocity with a significant radial component, with the positional effect proportional to the product of the parallax, the proper motion, and the radial velocity.

  9. TAU (spacecraft) - Wikipedia

    en.wikipedia.org/wiki/TAU_(spacecraft)

    TAU concept art Stellar parallax is the basis for the parsec, which is the distance from the Sun to an astronomical object that has a parallax angle of one arcsecond. (1 AU and 1 pc are not to scale, 1 pc = ~206265 AU) What TAU would do is use its distance from the Earth to make the parallax measurement, so rather than just 1 AU as with an Earth-based annual parallax it would be hundreds of AU.