HIPPARCOS, also known as the High Precision Parallax Collecting Satellite, is an astrometry satellite launched by the European Space Agency (ESA) in 1989. The name "HIPPARCOS" is an acronym derived from the Greek astronomer Hipparchus, who is often regarded as the founder of trigonometry and the first person to make systematic stellar observations.
HIPPARCOS was designed to accurately measure the positions, distances, and motions of celestial objects, particularly stars, with unprecedented precision. It achieved this by employing the method of astrometry, which involves measuring the apparent positions of celestial bodies with respect to other background stars. By recording and analyzing these data, HIPPARCOS aimed to construct a precise three-dimensional map of the Milky Way galaxy and improve our understanding of stellar evolution, as well as the structure and dynamics of our galaxy.
Equipped with a 29-centimeter telescope and an array of sensitive detectors, HIPPARCOS made incredibly precise stellar measurements using the principle of parallax. Parallax is the apparent shift in the position of an object when observed from different vantage points, and by measuring this shift for stars over a period of several years, HIPPARCOS could calculate their distances with remarkable accuracy.
The data collected by HIPPARCOS had a huge impact on astrophysics and astronomy. Its measurements significantly improved our understanding of star formation, the distribution of dark matter in the galaxy, and the nature of binary star systems. HIPPARCOS data also served as a baseline for subsequent missions, such as the Gaia satellite, which was launched by the ESA in 2013 with the sole purpose of mapping the positions and motions of over a billion stars in our galaxy.
