 Since 1838, many astronomers have spent decades measuring star parallaxes, but the work is so painstaking that up until 1989, only a few hundred were measured. That's out of a total population of over 1,500 stars within 60 light years from us. In 1989, however, the European Space Agency launched a spacecraft called Hipparchus. It was specially designed to accurately measure parallaxes without all the interference from the Earth's atmosphere. It did so for over 118,000 stars. Hipparchus is accurate to within 5 to 10 percent for stars within 650 light years.