Comet IRAS-Araki-Alcock was jointly discovered, in 1983, by the Infrared Astronomical Satellite (IRAS) and ground-based astronomers Genicki Araki and George Alcock. When first detected, the comet’s orbit could not be accurately determined. Scientists even worried that it might strike the Earth. Fortunately, it did not; instead, it came within about 750 Earth radii—a stone’s throw in astronomical terms. 
    The word “comet” derives from the ancient Greek name for “long-haired star.” In 1531 a European astronomer noted that comet tails point away from the Sun, an observation previously made by the ancient Roman philosopher Seneca as well as by Chinese astronomers. (Chinese