Parallax measurements for nearby stars
Parallax measurements for nearby stars
The graphic illustration shows how New Horizons has effectively enlarged the baseline for stellar parallax measurements, i.e. for the astronomical trigonometric determination of the distance to other stars. When making Earth-bound measurements, observers have a maximum baseline of just two astronomical units (1 AU = 150 million kilometres), 182 days apart. The angles measured and the apparent change in position along the different lines of sight are therefore small. New Horizons has extended the baseline to 47 AU. As a result, the apparent positional change of a nearby star is larger and more pronounced, relative to the distant background stars. Nevertheless, conventional parallax measurements have been more accurate so far, as the number of observations is higher for each star. The highest accuracies in distance determination are currently achieved using ESA's Gaia astrometry satellite, which observes the stars of the Milky Way from the Lagrange point L2.
