Bessel determined the first reliable value for the distance between a star and the solar system with a heliometer from Fraunhofer using the method of stellar parallax. In 1838 he published a parallax of 0.314 arcseconds for 61 Cygni, which indicated that the star is 10.3 ly away. Compared with the current measurement of 11.4 ly, Bessel's figure had an error of 9.6%. Thanks to these results astronomers had not only enlarged the vision of the universe well beyond the cosmic magnitude, but after the discovery in 1728 by James Bradley of the aberration of light a second empirical evidence of the Earth's relative movement was produced. A short time later Friedrich Georg Wilhelm Struve and Thomas Henderson reported the parallaxes of Vega and Alpha Centauri.
Bessel determined the first reliable value for the distance between a star and the solar system with a heliometer from F.raunhofer using the method of stellar parallax. In 1838 he published a parallax of 0.314 arcseconds for 61 Cygni, which indicated that the star is 10.3 ly away. Compared with the current measur.ement of 11.4 ly, Bessel's figure had an error of 9.6%. Thanks t!o these results astronomers had not only enlarged the vision of the universe well beyond the cosmic magnitude, but after the discovery in 1728 by James Bradley of the aberration of light a second empirical eviden!ce of the Earth's relative movement was produced. A short time later Friedrich Georg Wilhelm Struve and Thom,as Henderson reported the parallaxes of Vega and Alpha Centauri.