Jupiter in 2024/25: Report no.4: NTBs jet outbreak begins

John Rogers (2025 Jan.12)

A new outbreak on the NTBs jetstream began on 2025 Jan.10.  It consists of a bright spot in the fastest jet on the planet, and should quickly become a spectacular disturbance.

The spot was absent in the early hours of Jan.10 in images by Mike Karakas. It was first recorded on Jan.10 at 09:34 UT by Isao Miyazaki, as a small, weakly-bright spot in near-IR (>685nm) and the methane band (889 nm).  However it was first noticed on the next rotation, between 18-20h UT, by Clyde Foster (who first reported it), Manos Kardasis, Dominique Dierick, Geof Lewis, and Michel Szlosser.  By that time it was very bright in near-IR and methane and also in visible light, although very small. By Jan.11, ~13:30-16:00, it was very bright in all three wavebands as imaged by multiple observers in Japan and beginning to extend to the NW.  Some of the images from the first two days are shown in the attached compilation.

The initial longitude was approx. L1 = 168, L3 = 30.  It is likely to decrease in longitude by ~-5 deg/day in L1, -12 deg/day in L3.  The bright spot is a convective plume extending up to very high altitude, and it will begin to generate a dark turbulent wake over the coming week.  There are usually several (2-4) such eruptions at different longitudes within a few days or weeks, so please image all longitudes as often as possible in order to spot any new ones.

We have been expecting this outbreak on the basis of the disappearance of the NTB, the speed of the NTBs jet last year, and the 4- to 5-year periodicity of these outbreaks (Ref.1).  The previous outbreak, 4.4 years ago, was described in our 2020 final report and links therein (Ref.2).

Ref.1:  Rogers J, Adamoli G, Bullen R, Jacquesson M, Mettig H-J & Hahn G (2024),  ‘Jupiter in 2023/24, Report no.3:  The major jets.’  https://britastro.org/section_information_/jupiter-section-overview/jupiter-in-2023-24/report-no-3-the-major-jets

Ref.2:  Rogers J & Adamoli G (2021):  ‘Jupiter in 2020, Report no.9: Final report on northern hemisphere.’    https://britastro.org/section_information_/jupiter-section-overview/jupiter-in-2020/jupiter-in-2020-report-no-9-final-report-on-northern-hemisphere