Search for extra-solar planets

A number of different observational techniques are used today for the detection of planets beyond our solar system. Most of them are indirect methods, based on dynamical or photometric effects induced by the planet and measured on the parent star. The most successful technique so far has been the Doppler (radial-velocity) method, based on precise measurements of small variations in the radial velocity of the parent star. About one hundred extra-solar planets have been discovered by this technique. Other methods are based on astrometric measurements, direct imaging, photometry, interferometry and gravitational microlensing. Some of these techniques are already able to produce positive results, but many of them axe future projects needing more advanced instrumentation. In this paper the most important techniques for extra-solar planet detection will be reviewed and their results summarized. In the second part, two different projects carried out at Mt John University Observatory, Lake Tekapo, New Zealand will be presented, both involved in planet hunting. One is the HERCULES radial-velocity programme and the other is the MOA microlensing project.