NTB were the normal, reddish brown color, much of it had taken on this fainter, gray appearance. By December 2002, images by Parker revealed that the NTB had mostly vanished with only a few remaining dark segments scattered around the planet. On February 22, 2003 a CCD image taken by Eric Ng of Hong Kong, revealed a short segment of NTB, 20° long, near System 2 longitude 320°. By May 3, 2003 a CCD image by Christophe Pellier revealed a very short, faint segment of the NTB near System 2 longitude 140° (Fig. 3.8). I saw no remnants of the NTB in CCD images after that date. The NTB continues to be absent through July 2006. This gives Jupiter the appearance of having a bright alabaster zone stretching from the north edge of the NEB to the NPR with only a faint, bluish gray north tropical band south of the NTB's normal position. In some high-resolution CCD images, a faint bluish-gray band can also be made out in the north temperate zone (NTZ). Do not mistake these bands for remnants of these two belts, as they are not (Fig. 3.6). According to Peek [3] and Rogers, NTB fadings normally last for periods from 8-13 years [4]. As recent as February 2007, the NTB was absent. However, that began to change in late March and by April 27, 2007, the NTB was almost completely restored. We must be always alert because sometimes events really do happen just this quickly!

Some of the most interesting, visual features of the NTB may be the so-called rapid moving spots (RMS) that are sometimes present. According to Peek, "in 1880 there appeared for the first time in Jupiter's recorded history an outbreak of dark spots at the south edge of the NTB that displayed the shortest rotation periods that had ever been observed on Jupiter" [5]. The drift rates of the RMS are incredibly fast. These spots are seen on the southern edge of the NTB (NTBs) when present and may reside within the NTBs prograding jet stream. This jet stream is the fastest jet stream on the planet. The RMS may also be associated with the NTBs jet stream outbreaks. These outbreaks appear to have had periods of 10 years in the past and more recently 5 years [6]. Although a few suspicious features were observed during the 2000-2001 and 2001-2002 apparitions, the last notable outbreak of RMS seen visually seems to have occurred in 1997. In that year, several spots were recorded and observed throughout the apparition. These 1997 RMS had a drift rate of -56 to -57° per 30 days. These spots appear to have been associated with the North Temperate Current C (NTC C). NTB outbreaks may also result in the appearance of white spots or ovals.

Fig. 3.8. A highly detailed webcam image of Jupiter taken on January 5, 2003. Note the discontinuous, fragmented NTB and narrow NEB. The EZ appears to be very disturbed and south temperate oval BA is seen on the STBs. South is up. (Credit: Ed Grafton).

In addition to observations of the RMS, the NTB can also fade, and it can exhibit a shift in latitude. Dark spots and streaks can also appear on the north edge (NTBn) of the NTB from time to time [7]. During the 2000-2001 and 2001-2002 apparitions, several dark condensations could be observed on the NTBn. A few observers even detected faint gray festoons streaming away from some of these dark condensations, stretching into the brighter NTZ. Occasionally, a bright oval could be seen on the NTBn, intruding noticeably into the NTB. These features were easily seen in the better amateur CCD images.

Separating the NTB and the NNTB is the NTZ. The NTZ can exhibit some interesting features worth monitoring by amateurs. On many occasions the NTZ simply appears dusky gray, approaching the bland appearance of the polarregions with no distinctive markings. At other times it can appear much brighter, being a distinct divide between the NTB and NNTB. During the 2000-2001 apparition, the NTZ was described as almost alabaster by many observers. Indeed, the zone rivaled the north tropical zone in brightness, appearing brighter than the north tropical zone to many observers. During the apparition of 2001-2002, several segments of the NTZ were observed to be rather dusky in appearance while the remainder of the zone was bright. These dusky segments may be caused by the absence of bright, high altitude clouds at these longitudes. Changes such as these in the appearance of a zone are worth careful monitoring and should certainly be reported. During 2006, the NTZ was very bright with no obvious activity.

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