NASA’s Juno spacecraft has cruised through the Jupiter system in recent years, taking photos and measurements of the solar system’s largest planet. Juno recently reached the end of its pre-planned mission, but NASA extended it for a few more years. There’s a lot to see on and around Jupiter, such as the asteroid impact that Juno captured in 2020.
Jupiter is a huge planet with a correspondingly tremendous gravity. As such, it is hit by a lot of space debris. However, Rohini Giles of the Southwest Research Institute says most of these minor effects are minor and so short lived that it is unusual to see them. Giles is the lead author of a new study published in Geophysical Research Letters outlining the arguments for this rare impact detection.
According to Giles, the bright flash of the end of 2020 stood out in the data. Juno spent a lot of time scanning Jupiter’s powerful magnetic field and aurorae, but the flash on April 10, 2020 had a different spectral signature. It lasted only 17 milliseconds, but that was much longer than Transient Luminous Events (TLEs) that are common in Jupiter’s upper atmosphere. The spectral characteristics were also quite different, as indicated by the probe’s ultraviolet spectrograph (UVS).
Giles’s team concluded that this bright flash (pictured above) came from an asteroid or comet that fell into Jupiter’s atmosphere and exploded as it warmed. Based on the brightness of the flash, the team estimated that the object had a mass of 550 to 3,300 pounds (249 to 1,496 kilograms), making it far too small to leave marks on the gas giant. Comet Shoemaker-Levy hit 9 Jupiter in 1994, but it was more than a mile wide. Teams who followed up after that impact found visible scars and X-rays that took months to disappear.
These effects can have major consequences for even large planets. Fifteen years after Shoemaker-Levy 9, that object was still responsible for 95 percent of the water in Jupiter’s stratosphere. If the 2020 unnamed impactor caused local effects, Juno could not detect it. However, Juno has a few more years to keep an eye on more space rocks entering the planet.
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