"40 Years Later: Insights Gained from Surprise Comet Flyby"

In April 1983, a new comet was discovered by the InfraRed Astronomical Satellite (IRAS) and was named IRAS-Araki-Alcock. It made a close approach to Earth, passing within 3 million miles, and was visible to the naked eye. The comet was studied by astronomers and radar signals were bounced off it to determine its radius, rotation, and composition. Close approaches of comets to Earth are infrequent, but there have been several comets that may have approached Earth even more closely since 1983. Halley's Comet, the most famous of all comets, passed just 3.1 million miles from Earth in 837 and will pass within 8.6 million miles in 2134.