In 1952, the Palomar Observatory imaged a close grouping of three point-like light sources, measuring 15th magnitude in brightness. It took another image an hour later, and the three objects had vanished. Follow-up observations scanned the area down to 21st magnitude and they were still missing. Now astronomers have used the 10.4-m Gran Terescopio Canarias, which should have seen anything brighter than 25.5 mag. Still nothing. What were they, and where did they go?
I like this idea. There's something shark in the water-ish about having three more planet(oids) in the solar system that we only caught a glimpse of for an hour in 1952. It reminds me of Melancholia.