Comet C/1919 Q2 Metcalf catches the attention. The intriguing object was discovered in August of 1919 and remained visible until early 1920, but no subsequent observations have been made. In 1973, Allan Cook discovered that the Omicron Draconids meteor stream seemed to be following the orbit of the earlier comet. Suspicion is strong that the comet broke up and that the Omicron Draconids are simply the result of that event, a manifestation of cometary debris.
All of which makes the fireball that streaked through European skies last July a bit more interesting than your average bolide. A new paper will suggest that the boulder that caused it — probably a meter across and massing 1.8 tons — was a chunk of the original comet, a boulder that broke apart from the original ice and rock nucleus as C/1919 Q2 Metcalf disintegrated. That would mean we have comet fragments out there waiting to be discovered. Josep M. Trigo-Rodríguez (Institute of Space Sciences, CSIC-IEEC, Spain) explains:
“If we are right, then by monitoring future encounters with other clouds of cometary debris, we have the chance to recover meteorites from specific comets and analyse them in a lab. Handling pieces of comet would fulfill the long-held ambitions of scientists – it would effectively give us a look inside some of the most enigmatic objects in the Solar System.”
Image: A close-up image of the Bejar bolide, photographed from Torrelodones, Madrid, Spain. Credit: J. Perez Vallejo/SPMN.
A fascinating prospect indeed. The fireball was seen on July 11, 2008 at 2117 UTC, reaching an intensity 150 times brighter than the full Moon. Tracked by three stations of the Spanish Fireball Network, it disappeared at an altitude of 21.5 kilometers above the town of Bejar, near Salamanca in Spain. Studying large pieces of a comet in a laboratory would reward the search for fragments, but tracking them down won’t be easy. The paper is Trigo-Rodríguez et al., “Observation of a very bright fireball and its likely link with comet C 1919 Q2 Metcalf,” scheduled for publication in Monthly Notices of the Royal Astronomical Society (abstract). An RAS news release is also available.