On 6 July 2011 NASA's Solar Dynamics Observatory, observed comet C/2011 N3 plunging into the sun. Scientists theorize that this happens quite a lot, but this is the first time it has actually been witnessed, the closest that has been seen in the past is the Solar and Heliospheric Observatory, a joint mission between NASA and theEuropean Space Agency, witnessing comets passing behind the sun and failing to reappear.
Video made from the images taken by the Solar Dynamics Observatory, which takes one frame every 12 seconds. From NASA.
A formal description of this even has now been published in a paper in the journal Science by a team lead by Carolus Schrijver of the Lockheed Martin Advanced Technology Centre in Palo Alto, California. This describes C/2011 N3 (meaning the 3rd comet discovered in the 25th and 26th weeks of the year) fell to within 100 000 km of the solar surface, breaking up into several pieces before totally evaporating. In the last 10 minutes of its decent it lost between 600 and 60 000 tonnes of mass, implying a core nucleus diameter between 10 and 50 meters in diameter (not usually something that can be measured).
Still image assembled from the Solar Dynamics Observatory data. Also from NASA.