A New Strategy for SETI: Earth as an Exoplanet

UoM administered thesis: Master of Science by Research

  • Authors:
  • Andreea Dogaru


Over 3,800 exoplanets have been discovered so far, although none of them are quite like our Earth in terms of the mass-radius ratio and the distance from the host star. For example, even if a few exoplanets have a mass similar to Earth’s, their radius is unknown and/or they are significantly closer to the host star than Earth is to the Sun. There are several ways of detecting exoplanets e.g. two very successful ones that led to the discovery of 94% of exoplanets i.e. transit photometry and radial velocity (RV), as well as astrometry, which is a promising method that could revolutionise the exoplanet detections in the near future. These methods can, however, be employed by an intelligent civilisation on a faraway planet to detect the Earth. In this dissertation, a new SETI strategy is developed, how detectable the Earth is from outer space. Earth’s detectability as an exoplanet is investigated to find out which stars have the best view of us. In this way, the stars in the proximity of which we are most likely to receive a SETI signal from are investigated. Signal-to-noise ratios (SNRs) of the Earth as seen from 1.6 million stars in the Milky Way are derived, first for each individual detection method and then by combining all or two specific detection methods. The detectability is measured by considering the sensitivity of the detection methods. Maps of the Milky Way are obtained which outline which portions contain the highest SNR stars. Four SETI surveys, that have a well known sky coverage, are plotted over the combined map and the resolutions of three of them along with an array of telescopes involved in the SETI research are calculated to examine their resolution as a function of wavelength. Finally, a crossmatch is made in between the target stars and the hosts of the confirmed exoplanets. Sixty-six good exoplanet matches within 1 arcsecond are revealed, three of which are terrestrial and four that are potentially terrestrial.


Original languageEnglish
Awarding Institution
Award date1 Aug 2019