Jupiter in 2024/25, Report no.6: Other recent developments on Jupiter

John H. Rogers (BAA),                                                                                                                        (2025 April 19)

including data from Shinji Mizumoto (ALPO-Japan), Gianluigi Adamoli, Rob Bullen, Michel Jacquesson, Hans-Jörg Mettig, & Marco Vedovato (JUPOS team)

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Following the NTBs outbreak, here is a brief summary of other interesting phenomena on the planet in recent months, with a labelled map of the planet in late March. (Another labelled map can be found in our report on PJ69.)

NNTBs jet outbreak? There are usually dark spots on the NNTBs (N2) prograde jet, but they tend to disappear during NTBs jet outbreaks.  Up to late Jan., the JUPOS chart showed these spots at all longitudes, with fewer thereafter. However, most of the spots were small and inconspicuous, and their reduction from early Feb. onwards could be due to decreased image resolution.

NTB:  Our posted report only goes up to mid-March, after the plumes disappeared.  At that time, the reviving NTB(S) was starting to redden at some longitudes, and this continued to give an orange-tinted belt, with a narrow grey NTB(N) also present at some longitudes.  However, one sector did not redden and has faded greatly (L1 ~ 90-220 on March 28).

Marking the f. end of the reddish (brown) sector, an ‘orange blob’ developed in mid-March, on the NTBs edge at 24ºN, with a drift of DL1 = -0.7 deg/day (from L1=87 on March 19 to 69 on April 15). It is weakly methane-bright, and has become a darker brown.  Its outline has been rather diffuse so it’s not clear whether it is a vortex.

NEB:  This belt was very broad in 2024, but the N edge is starting to recede. All the anticyclonic white ovals (AWOs) are still white or light, but White Spot Z was quite dull before the outbreak and remains so.   Although they have not darkened as in previous NTBs outbreaks, all the AWOs are still affected by white streaks intruding from the disturbed NTropZ, even more than at the height of the NTBs outbreak.

Equatorial Zone:  There is much dark material in the EZ.  NEBs dark formations and festoons are conspicuous, and there is a broad, light grey-brown Eq. Band at all longitudes, indicating that a coloration event is again in progress.

S. Equatorial Disturbance: The main complex of the SED is still present although it has sometimes been difficult to see. The JUPOS chart is useful in showing it as a slow-moving gap in the chain of SEBn spots, and Shinji Mizumoto’s maps are useful in tracking it morphologically. It was conspicuous up to Dec.21-24, when it was at L1 ~ 100 with DL1 = +1.0 deg/day, passing the mid-SEB outbreak. Thereafter it became more variable and often subdued, esp. difficult to identify from Jan.25 to Feb.11 as it approached and passed (Jan.28) the GRS.  It tended to appear as a bright white oval without obvious rift, as on March 21-24 (L1 ~ 180, passing GRS) and April 2 (L1 ~ 200), though not thereafter. On April 11 it had its classic form again (L1 = 212).

Mid-SEB outbreak:  This had appeared on 2024 Nov. 11.  Shinji Mizumoto posted frequent maps of the outbreak (and an animation) on the ALPO-Japan web site, and tracked 6 individual plumes erupting from the f. end up to Dec.30 (as usual, nearly fixed in L2), then one at the p. end on Dec.25.  Some other, less conspicuous plumes also appeared at these two ends, but after Jan.17 outbreaks at the f. end ceased, and the whole disturbance prograded (~55-75º long). It is still active internally, and in March its p. end prograded more rapidly, so by April 3 it spanned ~95º longitude. It is now approaching the disturbance f. the GRS.

GRS:  The GRS remains very small, with a length of only 11.2º (S. Mizmoto) or 11.5º (JUPOS) throughout this apparition.  After an unexplained one-off shift of -4º long. during solar conjunction, its average drift has been steady at DL2 = -1.75 (±0.05) deg/30d.