Arecibo Observatory

The Arecibo Observatory has earned a reputation as the largest and most sensitive radio telescope in the world. It features the William E. Gordon telescope as well as a visitor and public outreach center and scientific research community. As more than 1,000 feet in size, it is the world’s biggest single aperture telescope. It is known also as the National Astronomy and Ionosphere Center (NAIC) and is run largely by the National Science Foundation. It was constructed in the mid-1960s in the space left in the ground from a karst sinkhole. 
With three radar transmitters, it has the largest electromagnetic-wave-gathering capacity in the world, within a forty-degree cone of visibility. Many breakthroughs and discoveries have been found by scientists from around the world in the facilities here, including the rotation rate of Mercury and evidence that neuron stars exist. The observatory was listed on the American National Register of Historic Places in 2008.

Practical Info

Visitors can learn more about the radio telescope and atmospheric science at the Observatory’s Ángel Ramos Foundation Visitor Center, open Wednesday to Sunday. Admission costs are $10 for adults and $6 for seniors and students. Don’t miss the amazing view from the Observation Deck. Drive there from San Jeuan in just over an hour.