Speaker
Description
To detect distant, low-mass exoplanets, the microlensing technique has been proven to be one of the most successful techniques. On the other hand, to detect the Earth as a rocky planet in the Solar system, the other technological civilisations could also use the microlensing technique. Assuming that technological civilisations have equal chance to be located around any star anywhere in the Galaxy, we can define the “Earth microlensing zone'' (EMZ) as the region of the sky from which observers may most likely see Earth's microlensing signal. The EMZ can be thought of as the microlensing analogue of the Earth Transit Zone (ETZ) from where observers see Earth transit the Sun. Just as for the ETZ, the EMZ could represent a game-theoretic Schelling point for targeted searches for extra-terrestrial intelligence (SETI). To compute the EMZ, the Gaia DR2 catalogue with magnitude G<20 is used to generate Earth microlensing probability and detection rate maps to other observers. We then show that Earth could be observable on average of thousands per year.
