Shocks created by the impacts led to high-temperature chemical reactions that produced hydrogen cyanide, which remains in the air but has been spread around a bit in the years since. The comet also delivered carbon monoxide and water, which through an interaction with sunlight, scientists suspect, was converted to carbon dioxide.

The hydrogen cyanide has diffused some both north and south, mixed by wave activity. Jupiter’s cloud bands carry material around the planet swiftly, but the bands do not mix easily. Not surprisingly, hydrogen cyanide is most abundant in a belt at the latitude where the comet was absorbed.

The highest concentration of carbon dioxide, however, has shifted away from the latitude of the impact. It is most prevalent poleward of 60 degrees south and decreases abruptly, toward the equator, north of 50 degrees south. Another smaller spike in its presence occurs at high northern latitudes, around 70 to 90 degrees north.

Perhaps the two chemicals got distributed at different altitudes, and are being moved around by different currents. Or maybe the formation of the carbon dioxide was more complex than thought. He said it might have involved carbon monoxide first moving away from the impact area and then interacting with other substances at higher latitudes before being converted to carbon dioxide.

These findings are the result of the Cassini spacecraft, now at Saturn, as it examined Jupiter in 2000 and 2001.