Description
In 1989, ESA launched the first space mission dedicated to astrometry – the science of charting the sky. The satellite was named Hipparcos, echoing the name of ancient Greek astronomer, Hipparchus, who compiled the oldest known stellar catalogue in the second century BC.
Hipparcos operated for over three years and a catalogue based on its data, released in 1997, had a major impact on many areas of astronomy research.
This catalogue listed 117 955 stars, reporting their positions with unprecedented accuracy, alongside estimates of their distance from us and motions through the Galaxy. It was a huge advance on the best catalogues compiled from ground-based observations, which contained information for just over 8000 stars.
The newly launched ESA Star Mapper visualisation is an exploration of some central aspects of astrometric star catalogues, using data from ESA’s Hipparcos mission.
