A University of Texas astronomer has photographed a rare eclipse of the distant planet Pluto, proving the existence of a moon and giving valuable clues to the planet`s size.
Graduate astronomy student Richard Binzel observed the eclipse Feb. 17 at UT`s McDonald Observatory near the town of Ft. Davis in west Texas.
The discovery of eclipses between Pluto and its moon also can help researchers determine Pluto`s size, Binzel said.
”Ever since the discovery of Pluto, its size has been uncertain,”
Binzel said. ”Now we can make a good guess at it.”
The existence of Pluto`s moon, called Charon, was postulated in 1978, when Navy astromomer James Christy observed that Pluto`s shape was distinctly elongated.
The inference was that Pluto, itself not seen until 1930, had a moon. But visual evidence was difficult to obtain because of Pluto`s great distance from Earth, averaging about 3.5 billion miles.
