Question

Exoplanets have been found using a variety of methods. As of May 2020, the following three methods had detected exoplanets as follows:

Transit measurements: 3038 planets
Gravitational microlensing: 120 planets
Astrometry: 10 planets

Explain some of the reasons for the differences in the numbers of detections for the methods listed above. (i.e. why have some methods resulted in many detections compared to other methods with fewer detections?)

Answer 1

The differences in the number of exoplanet detections using different methods can be attributed to the sensitivity and limitations of each method.

Step-by-step explanation:

There are several reasons for the differences in the number of detections for the methods used to find exoplanets.

Firstly, the transit method, which measures the dip in brightness of a star as a planet passes in front of it, has detected the most exoplanets. This is because it is sensitive to detecting large planets close to their parent stars, which are easier to observe.

Secondly, the gravitational microlensing method detects exoplanets by measuring the distortion of light caused by the gravitational pull of a planet. However, this method requires a rare alignment between the planet, star, and observer, leading to fewer detections.

Finally, the astrometry method, which measures small shifts in a star's position due to the gravitational pull of an orbiting planet, is less sensitive and less precise, resulting in fewer detections.