From aboard the Juno spacecraft, a Southwest Analysis Institute-led instrument observing auroras serendipitously noticed a brilliant flash above Jupiter’s clouds final spring. The Ultraviolet Spectrograph (UVS) crew studied the information and decided that that they had captured a bolide, a particularly brilliant meteoroid explosion within the fuel big’s higher ambiance.
“Jupiter undergoes an enormous variety of impacts per 12 months, way more than the Earth, so impacts themselves are usually not uncommon,” mentioned SwRI’s Dr. Rohini Giles, lead creator of a paper outlining these findings in Geophysical Analysis Letters. “Nevertheless, they’re so short-lived that it’s comparatively uncommon to see them. Solely bigger impacts might be seen from Earth, and you must be fortunate to be pointing a telescope at Jupiter at precisely the fitting time. Within the final decade, novice astronomers have managed to seize six impacts on Jupiter.”
Since Juno arrived at Jupiter in 2016, UVS has been used to review the morphology, brightness and spectral traits of Jupiter’s auroras because the spacecraft cartwheels near its floor each 53 days. Throughout the course of a 30-second spin, UVS observes a swath of the planet. The usinstrument has sometimes noticed short-lived, localized ultraviolet emissions outdoors of the auroral zone, together with a singular occasion on April 10, 2020.
“This remark is from a tiny snapshot in time—Juno is a spinning spacecraft, and our instrument noticed that time on the planet for simply 17 milliseconds, and we do not know what occurred to the brilliant flash outdoors of that timeframe,” Giles mentioned, “However we do know that we did not see it on an earlier spin or a later spin, so it should have been fairly short-lived.”
Beforehand, UVS had noticed a set of 11 brilliant transient flashes that lasted 1 to 2 milliseconds. They have been recognized as Transient Luminous Occasions (TLEs), an higher atmospheric phenomenon triggered by lightning. The crew initially thought this brilliant flash may be a TLE, nevertheless, it was totally different in two key methods. Whereas it was additionally short-lived, it lasted no less than 17 milliseconds, for much longer than a TLE. It additionally had very totally different spectral traits. Spectra of TLEs and auroras characteristic emissions of molecular hydrogen, the principle part of Jupiter’s ambiance. This bolide occasion had a easy “blackbody'” curve, which is what is anticipated from a meteor.
“The flash length and spectral form match up effectively with what we count on from an influence,” Giles mentioned. “This brilliant flash stood out within the information, because it had very totally different spectral traits than the UV emissions from the Jupiter’s auroras. From the UV spectrum, we will see that the emission got here from blackbody with a temperature of 9600 Kelvin, situated at an altitude of 140 miles above the planet’s cloud tops. By wanting on the brightness of the brilliant flash, we estimate that it was brought on by an impactor with a mass of 550-3,300 kilos.”
Comet Shoemaker-Levy was the biggest noticed Jupiter impactor. The comet broke aside in July 1992 and collided with Jupiter in July 1994, which was intently noticed by astronomers worldwide and the Galileo spacecraft. An SwRI-led crew detected impact-related X-ray emissions from Jupiter’s northern hemisphere, and outstanding scars from the impacts endured for a lot of months.
“Impacts from asteroids and comets can have a major influence on the planet’s stratospheric chemistry—15 years after the influence, comet Shoemaker Levy 9 was nonetheless liable for 95% of the stratospheric water on Jupiter,” Giles mentioned. “Persevering with to watch impacts and estimating the general influence charges is due to this fact an necessary component of understanding the planet’s composition.”
Rohini S. Giles et al, Detection of a bolide in Jupiter’s ambiance with Juno UVS, Geophysical Analysis Letters (2021). DOI: 10.1029/2020GL091797
Southwest Research Institute
Scientists picture a brilliant meteoroid explosion in Jupiter’s ambiance (2021, February 22)
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