The LIGO and GEO 600 detectors

In This Section

Laser Interferometer Gravitational Wave Observatory (LIGO)

LIGO has two locations in the United States – one in Livingston, Louisiana and the other in Hanford, Washington . Each site has an interferometer with 4-km long arms that are enclosed in 1.2-m diameter vacuum pipes. The Hanford location also has a smaller interferometer with 2-km long arms.


Aerial view of LIGO’s Livingston, LA facility. Image courtesy of LIGO Laboratory.	Aerial view of LIGO’s Hanford, WA facility. Image courtesy of LIGO Laboratory.

The two LIGO interferometers work together as one observatory. This is because changes in laser intensity, mini-earthquakes, and other local disturbances can look like gravitational wave signals. Local signals like these only register in one interferometer, but gravitational wave signals register in both. Therefore, comparing data from the two locations helps scientists figure out which signals are from local noise.

LIGO started collecting data in 2003. The observatory is the largest, most sensitive gravitational wave detector ever built. The sensitivity of LIGO will be increased even more over the next few years, by a series of upgrades to be completed in 2011. The upgraded LIGO will have a new type of mirrors, more powerful lasers, and better isolate the signal from outside noise.

For more information, visit the LIGO website.

Participating Institutions: California Institute of Technology, Massachusetts Institute of Technology