Details

Autor(en) / Beteiligte

• Brown, Shannon
• Janssen, Michael
• Adumitroaie, Virgil
• Atreya, Sushil
• Bolton, Scott
• Gulkis, Samuel
• Ingersoll, Andrew
• Levin, Steven
• Li, Cheng
• Li, Liming
• Lunine, Jonathan
• Misra, Sidharth
• Orton, Glenn
• Steffes, Paul
• Tabataba-Vakili, Fachreddin
• Kolmašová, Ivana
• Imai, Masafumi
• Santolík, Ondřej
• Kurth, William
• Hospodarsky, George
• Gurnett, Donald
• Connerney, John

Titel

Prevalent lightning sferics at 600 megahertz near Jupiter’s poles

Ist Teil von

• Nature (London), 2018-06, Vol.558 (7708), p.87-90

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2018

Beschreibungen/Notizen

• Lightning has been detected on Jupiter by all visiting spacecraft through night-side optical imaging and whistler (lightning-generated radio waves) signatures 1 – 6 . Jovian lightning is thought to be generated in the mixed-phase (liquid–ice) region of convective water clouds through a charge-separation process between condensed liquid water and water-ice particles, similar to that of terrestrial (cloud-to-cloud) lightning 7 – 9 . Unlike terrestrial lightning, which emits broadly over the radio spectrum up to gigahertz frequencies 10 , 11 , lightning on Jupiter has been detected only at kilohertz frequencies, despite a search for signals in the megahertz range 12 . Strong ionospheric attenuation or a lightning discharge much slower than that on Earth have been suggested as possible explanations for this discrepancy 13 , 14 . Here we report observations of Jovian lightning sferics (broadband electromagnetic impulses) at 600 megahertz from the Microwave Radiometer 15 onboard the Juno spacecraft. These detections imply that Jovian lightning discharges are not distinct from terrestrial lightning, as previously thought. In the first eight orbits of Juno, we detected 377 lightning sferics from pole to pole. We found lightning to be prevalent in the polar regions, absent near the equator, and most frequent in the northern hemisphere, at latitudes higher than 40 degrees north. Because the distribution of lightning is a proxy for moist convective activity, which is thought to be an important source of outward energy transport from the interior of the planet 16 , 17 , increased convection towards the poles could indicate an outward internal heat flux that is preferentially weighted towards the poles 9 , 16 , 18 . The distribution of moist convection is important for understanding the composition, general circulation and energy transport on Jupiter. Observations of broadband emission from lightning on Jupiter at 600 megahertz show a lightning discharge mechanism similar to that of terrestrial lightning and indicate increased moist convection near Jupiter’s poles.