NASA's Jet Propulsion Laboratory, it will be possible to measure stellar positions to within 20 millionths of an arcsecond by 2005.
ECONOMIST: A roadmap for planet-hunting
2.
Viewed from a distance of ten light-years, the sun's side-to-side wobble due to Jupiter causes its position to change by 1.6 thousandths of an arcsecond.
ECONOMIST: A roadmap for planet-hunting
3.
It will have two telescopes mounted at opposite ends of a ten-metre boom, and will be able to measure astrometric wobbles as small as a millionth of an arcsecond.