PARIS, July 26 (UPI) -- European scientists studying the atmosphere of Neptune say they've seen evidence a comet collided with the planet about 200 years ago.
Analyzing the composition of Neptune's atmosphere, using data from the European Space Agency's orbiting Herschel space telescope, researchers found an unexpected distribution of carbon monoxide, indicating a possible comet impact, SPACE.com reported Monday.
Studying similar impacts on Jupiter and Saturn has helped astronomers detect the telltale signs of cometary impacts, SPACE.com said.
Comets, sometimes described as "dirt snowballs," leave traces of their impact with the atmospheres of gas giants like Jupiter and Neptune in the form of water, carbon dioxide, carbon monoxide, hydrocyanic acid and carbon sulfide.
Such traces gases, especially carbon monoxide, were detected in higher than expected amounts in the upper levels of Neptune's atmosphere, ESA scientists said.
"The higher concentration of carbon monoxide in the stratosphere can only be explained by an external origin," Paul Hartogh, principle investigator of the ESA Herschel science program, said.
