The first planets outside the solar system were discovered around Pulsar B1257+12, a rapidly rotating pulsar with three Earth-like planets in orbit. ( early 1990s )
One of its first accomplishments: Establishing the rotating rate of Mercury, which turned out to be 59 days rather than the previously estimated 88 days ( 1965 ).
Detailed maps of the distribution of galaxies in the universe ( late 1980s ).
The first pulsar in a binary system was discovered ( 1974 ), leading to important confirmation of Einstein's theory of general relativity and a Nobel Prize for astronomers Russell Hulse and Joseph Taylor ( 1993 ).
Investigations of ice craters at the polar regions of the planet Mercury with the radar system ( 1990s ) and similar investigation of the lunar poles for evidence of ice ( 1997 ).
Provided much of our pre-Magellan mission knowledge of the surface of Venus via 1.5 km resolution imagery of the surface through the planet's cloud cover using the radar system.
The observatory has made major contributions to our understanding of the chemistry and dynamics of the Earth's upper atmosphere and ionosphere.
Discovery of two classes of pulsars: millisecond pulsars, which rotate several hundred times per second, and slower-rotating pulsars, which rotate about once per second. The slow-rotating pulsars speed through space, while millisecond pulsars move slowly through space.
Arecibo Observatory is uniquely suited to search for signals from extraterrestrial life, by focusing on thousands of star systems in the 1,000MHz to 3,000 MHz range. No such signals have been found.
Arecibo Observatory has provided a unique setting for Hollywood filmmakers. The observatory was the setting for the climatic scenes in the James Bond movie
, and a good portion of the movie
, based on a novel by Carl Sagan and starring Jodie Foster, takes place at Arecibo. Another science fiction movie called
was filmed on observatory grounds.