Periodic comet 73P/Schwassmann-Wachmann 3 has now broken into more than 30 different pieces as it approaches the Sun, scientists at NASA’s Jet Propulsion Laboratory report.

The comet, discovered May 2, 1930, by Arnold Schwassmann and Arno Wachmann at the Hamburg Observatory in Germany, was the third periodic comet discovered by the pair and the 73rd comet to be recognized as periodic.

Because of poor observing conditions, the comet was not recovered during its next return to perihelion in 1935-1936. As a result, calculations of the comet’s orbit were rough and its close passes by Jupiter in October 1953, at 0.9 AU, and November 1965, at 0.25 AU, further degraded astronomers’ predictions.

An Astronomical Unit is about 93 million miles, or the distance between Earth and the Sun.

The comet was re-discovered on Aug. 13, 1979, missed during the next return to perihelion in 1985-1986 – again because of poor observing conditions – and then observed during its returns in 1990, 1995-1996, 2000-2001 and the current 2005-2006 encounter.

In late 1995, the comet began to break up into fragments. The main comet – now called fragment C – has further split into fragments A and B.

In 2001, fragment C was observed along with the fragment B and a new fragment E.

During its 2006 return to perihelion, which for fragment C will take place on June 6 – just inside the Earth’s orbit – the comet has fragmented into more than 30 additional pieces. All of the observed fragments in 2006 will pass relatively close to Earth between May 12 and May 28, but none will pass closer than 5.5 million miles.

Astronomers consider the nearby passes of the fragments an excellent opportunity to examine the cometary breakup process and they hope their observations will improve understanding of why comets disrupt.

Apparently some comets have very weak internal structures, and perhaps rapid rotation or the pressure of vaporizing interior ices, as the comet approaches the warming Sun, causes the breakup events.

In addition to ongoing ground-based visual observations, the Hubble Space Telescope and the Spitzer infrared space telescope are continuing to monitor the comet. The Arecibo and Goldstone planetary radars will begin their observations on April 30.