Astrometric searches try to detect directly the motion of the star. To get a feel for the difficulty of astrometric searches , suppose that we lived on the nearest star to the Earth (excluding the Sun), Proxima Centauri. Could we see our Solar System? Proxima Centauri is at a distance of 4.3 light years or 40 trillion kilometers from the Earth. This is a long way away -- 1 Astronomical Unit = 8.3 light minutes.

Jupiter orbits in our Solar System in an orbit of size 5.2 A. U. with orbital period of 11.9 years. From the distance of Proxima Centauri this would correspond to an orbit of angular size ~ 0.004 arc-seconds. Recall 1 degree = 60 arc minutes. 1 arc-minute = 60 arc-seconds ===> 1 arc-second = 1/3,600 of a degree!! Given current technology for ground-based observatories, this is not do-able.

There are currently no good candidates based on astrometric searches. In the future, we will develop space-based experiments which will have pointing accuracies of better than 0.00001 arc seconds and thus will be able to see nearby planetary systems.