Still, there is a paucity of surface features that can be unambiguously interpreted as cryovolcanoes. One of the first of such features revealed by "Cassini" radar observations in 2004, called Ganesa Macula, resembles the geographic features called "pancake domes" found on Venus, and was thus initially thought to be cryovolcanic in origin, until Kirk et al. refuted this hypothesis at the American Geophysical Union annual meeting in December 2008. The feature was found to be not a dome at all, but appeared to result from accidental combination of light and dark patches. In 2004 "Cassini" also detected an unusually bright feature (called Tortola Facula), which was interpreted as a cryovolcanic dome. No similar features have been identified as of 2010. In December 2008, astronomers announced the discovery of two transient but unusually long-lived "bright spots" in Titan's atmosphere, which appear too persistent to be explained by mere weather patterns, suggesting they were the result of extended cryovolcanic episodes.