Atacama Cosmology Telescope

The Atacama Cosmology Telescope is a radio telescope with a 6-meter diameter mirror operating at 5,190 meters elevation in the Atacama Desert in northern Chile. The instrument receives microwave radiation from the early universe and relies on the extremely dry air of this mountain region for its observations.

The telescope began operations in October 2007 and worked continuously until 2022 mapping radiation from the early universe. During this period, its observations contributed significantly to our understanding of cosmic history.

The observatory attracts researchers from around the world who collaborate here to investigate questions about the origin and evolution of the universe. The international makeup of the teams reflects how this kind of research matters globally.

The telescope sits on a high mountain plateau with very dry air, which is necessary for precise measurements of microwave radiation. Visitors should know that the location is at high elevation and requires careful planning to reach.

The telescope discovered structures in the cosmic background radiation that other instruments had missed, providing new insights into how matter is distributed throughout the universe. These observations revealed how galaxies appear distorted by cosmic curvature and allowed a better understanding of invisible matter.

Location: Atacama Desert

Inception: 2007

Diameter: 6 m

Part of: Llano de Chajnantor Observatory

Website: https://act.princeton.edu

GPS coordinates: -22.95861,-67.78750

Latest update: December 12, 2025 15:11