Britannica Sources used in this answer

How was the Arecibo Observatory used before its central platform collapsed?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Telescope Aerial view of the Keck Observatory's twin domes, which are opened to reveal the telescopes. Keck II is on the left and Keck I on the right.

Before its central platform collapsed in 2020, the Arecibo Observatory in Puerto Rico served as a world-leading radio telescope for diverse astronomical research. Its 305-metre spherical reflector allowed scientists to track celestial objects and conduct significant studies, including:

Planetary Science: The observatory produced detailed radar maps of Venus and Mercury. It notably discovered that Mercury rotates every 59 days, rather than 88 as previously thought.1
Pulsar Research: Scientists used the facility to discover the first extrasolar planets orbiting a pulsar (B1257+12) and the first binary pulsar, which provided critical evidence for Albert Einstein’s theory of general relativity.1
SETI Programs: The telescope was a key instrument for the Search for Extraterrestrial Intelligence, participating in projects like Project Phoenix and Project SERENDIP V to scan the skies for potential signals.2
Atmospheric Study: The site also utilized a high-power laser facility to investigate Earth’s atmosphere.1