Did a Comet Hit Neptune 200 Years Ago?

Researchers studying Neptune's atmosphere found evidence that a comet may have hit the planet about two centuries ago. Was this a "cold-case" file re-opened, or did they discover a way to travel back in time to witness a long-ago event? To make the discovery, a team from the Max Planck Institute for Solar System Research actually used the Herschel Space Telescope's PACS (Photodetector Array Camera and Spectrometer) instrument, along with what was learned from observations from when the Shoemaker-Levy 9 hit Jupiter sixteen years ago.

The 1994 impact on Jupiter was watched and documented by Voyager 2, Galileo and Ulysses, and today this data helps scientists detect cometary impacts that happened many, many years ago. In fact, just in February of this year, scientists from Max Planck discovered strong evidence for a comet impact on Saturn about 230 years ago. These "dirty snowballs" leave traces of water, carbon dioxide, carbon monoxide, hydrocyanic acid, and carbon sulfide in the atmosphere of the gas giant planets. These molecules can be detected in the radiation the planet radiates into space.

So, the team turned their attention to Neptune, and used the PACS to analyze the long-wave infrared radiation of Neptune.…

See Universe Today for links to further info.

Also see ScienceDaily.com.