Infrared measurements of the Neptune stratosphere — the planet furthest from the sun, 30 times farther than we are from the Sun — suggest that a huge comet would have impacted Neptune in the recent past, about 1000 years ago.
Astronomers have long sought to know where the abnormal abundance of carbon monoxide (CO) on Neptune could come from. This phenomenon ended up being associated with the impact of comets that would have crashed on the planet, which ended up altering its atmosphere. Recently, researchers wanted to confirm this hypothesis by looking for carbon disulfide (CS), another molecule usually associated with the presence of a comet. The latter has also been observed continuously in the atmosphere of Jupiter since the impact of the comet Shoemaker-Levy 9 in 1994.
Based on data from the Atacama Large Millimeter Array (ALMA) network in Chile, the researchers detected the presence of carbon disulfide. “We report the detection of CS in the atmosphere of Neptune, the first unambiguous observation of a sulfur species in a giant planet beyond Jupiter,” the researchers confirm in a study published in Astronomy & Astrophysics.
Carbon disulfide appears to be present in small amounts at the submillimeter levels. Its privileged origin here would be the impact of a large comet of about 2-mile wide, which occurred several centuries ago — about 1000 years ago. Astronomers believe that on Neptune, such a phenomenon can occur every 3400 to 4100 years, which is common on the scale of the Universe.
It remains incredible that we can – from Earth – detect the presence of such a molecule in such minute proportions. NASA expressed a few months ago its intention to send an orbiter and an atmospheric probe directly on site by 2030 to study in depth the rings, the satellites, the atmosphere and the magnetosphere of the giant. Such a mission should teach us more about the origins of the solar system, but also the newly discovered exoplanets, as the similarities are numerous.