In the northwest mountains of the island, nestled among the karst-country hills, is the Arecibo Ionospheric Observatory, or Radio Telescope, the largest of its kind and one of the most important research facilities on the face of the earth.
The huge dish—more than a dozen football fields could fit inside—sits in a sinkhole and is forever aimed at the sky, tuned to detect the slightest sounds emitted by the farthest stars.
It is the place where planets outside our solar system were discovered and is the home base for NASA’s SETI, the Search for Extra-Terrestrial Intelligence, which you may remember from the Jodie Foster movie “Contact,” part of which was filmed here.
In the Visitors’ Center you will see how the colossal structure is used to study radio emissions from distant galaxies, quasars, pulsars and many other cosmic sources. The exhibits are interactive and contain extensive information on astronomy and atmospheric science.
It is the impressive size and magnitude of the tiled dish that leaves visitors breathless when they hike to the viewing platform and see it glimmering in the sun. Indeed it is one of the only landmarks in Puerto Rico that can easily be seen from a jetliner passing by at 33,000 feet!
The Arecibo Ionospheric Observatory is open Wednesday to Friday from 12:00 PM to 4:00 PM and Saturday, Sunday and most holidays from 9:00 AM to 4:00 PM.
How to Get There
From San Juan take Road 22 to Arecibo. In Arecibo, take Road 129 to 134, then Road 635 to 625, which ends at the observatory.