Comet Hyakutake on 3/22/96. Click on image for full size (64 Kb) Courtesy of Night of the Comet/NASA

Comet Hyakutake was found on January 30, 1996 by a man in Japan named Yuji Hyakutake. He spotted it using strong binoculars. This comet was visible from late March until late April, 1996. On March 25, the comet reached its closest approach to Earth of 9.3 million miles away.

Comet Hyakutake has probably not approached Earth for thousands of years. Astronomers observing comet Hyakutake found large quantities of the molecules ethane (C₂H₆) and methane (CH₄), so far not found in other comets. Astronomers for the first time also observed X-rays being emitted from a comet.

Finding these usual molecules in a comet suggests that comet Hyakutake may be a new type of comet. An abundance of ethane comparable to that of methane implies that comet Hyakutake must have experienced very different conditions during its birth than other comets that do not contain ethane.