Why are there two LIGO observatories?

LIGO has two detectors ~3000 km apart for three main reasons:
Noise discrimination – separating local vibrations from real signals by comparing distant data.
Signal timing – gravitational waves travel at light speed; timing differences over 10 ms rule out false signals.
Source localization – two sites help narrow wave origins; adding more (like Virgo) improves precision, as in the 2017 neutron star event.

https://www.ligo.caltech.edu/page/ligo-detectors

Graphic by Mayara Pacheco

#Astrodon #GravitationalWaves