There are many ways that exoplanets are discovered. Pulsar timing is a process in which radio waves emitted by pulsars are timed. Shifts in the timing indicate the presence of an exoplanet. A more direct method of observing exoplanets is direct imaging, which uses thermal imaging to discover heat sources around a star. An anomalous heat source can indicate the presence of an exoplanet. The oldest and most common method of discovering exoplanets has traditionally been astrometry. This is the process of measuring a star’s position in the sky and tracking to see if it has an elliptical or circular orbit, suggesting an exoplanet in the area. One final method of discovering exoplanets is relativistic beaming. This process tracks changes in a star’s brightness that occur as a result of a planet influencing the star with its gravity well.