Detection Methods

There are several methods currently used to detect exoplanets. Some of these are more effective than others at finding exoplanets (see Figure 1) of a particular type (such as the 'hot Jupiters' or 'Earth-like' object).

Figure 1: Detections of exoplanets since 1988.
Credit: data from the exoplanet.eu website (13 November 2018)

Astrometry: detecting tiny changes in a star's position caused by the presence of an exoplanet or exoplanets.

Direct Imaging: spotting the faint glow of a planet far from its parent star by blocking the star's light.

Gravitational Microlensing: using the chance alignment and lensing effect of two stars with the nearer one to us having an exoplanet.

Pulsar Timing: detecting the time varying arrival of radio waves from energetic, highly magnetic neutron stars.

Radial Velocity: using spectroscopy to detect the characteristic blue- and red-shift of a star as its orbit is perturbed by an exoplanet.

Transit: detecting an exoplanet as it crosses the face of its parent star causing the light we detect to dim.