Forthcoming 2005 Mars


The Case of the 1990 Apparition

Masatsugu MINAMI

Japanese here

0°  Introduction: The apparition of Mars this year is the next one of the so-called great apparition, and so the 2005 Mars must be similar to the case we observed in 1990 which was really the next one to the 1988 great apparition. However, there is a slight difference: The planet Mars was at opposition in 1990 on 27 November (λ=340°Ls), while this year it will be at opposition on 7 November (λ=329°Ls). This is less different than the cases of 1988 and 2003 apparitions where the oppositions were widely different since they occurred at λ=277°Ls in 1988 while at λ=250°Ls in 2003. Here in 2005, the separation deceased to 20 days, and the difference of Ls also reduced by half.

We here so, for the sake of the 2005 observations, look back on the case of the 1990 how we experienced. It is recommended for the readers to refer to the Ls values and compare them with the coming values and days in 2005.


1°  General Review: The CMO treated the reports of the observations in 1990/91 twenty times (once or twice a month) from CMO #086 (5 April 1990 issue) to #105 (25 May 1991 issue). The domestic (Japanese) observers who contributed to the CMO was 18 in number and quite less than the total domestic contributors, 34, in 1988, The number of observations also reduced to 2700, 20% fewer than the 1988 results. Among them however, Tohru IWASAKI (Iw) obtained a total of 400 drawings the season, and Takashi NAKAJIMA (Nj) produced a total of 498 drawings that was the best he had given in those years (he was 51 of age in 1990: Nj produced further a total number of 591 drawings later in 1999). The present writer (Mn) obtained 888 drawings (285 at Otsu and 503 at Fukui), quite less than in 1986 and 1988.

According to the 1990/91 Report of the BAA given by Richard McKIM (RMk) (JBAA, vol 102, No 5, Oct 1992), the total number of the British Mars observers in 1990/91 was 33, and so very prevailed over us. Even then the total observers and the observations were reported to have reduced by half compared with the case of 1988.

The first observation of the present writer (Mn) was made on 4 January at Otsu, while the work was not yet on the right track. We however got off to a good start at the Observatory of the Fukui City Museum of Natural History as usual with Nj on 29 March (λ=193°Ls). In April (λ=195°Ls on 1 April) and May (λ=213°Ls on 1 May), the spc was clear and it was a stimulus to us. In June it looked roundish (φ23°S) and became smaller at the end of June (λ=251°Ls). Depressiones Hellesponticæ looked dark.  In 2005, the deepest central latitude read φ25°S at the end of May (λ=221°Ls), when nearly δ=8".

In 1990, the ccd imagers were not crowded, and in our country (ccd none yet) the observations became active after the angular diameter exceeded 9 arcsecs in August. In August there were reported about 350 drawings and TP/colour photo sets. In mid-August, the season reached λ=280°Ls, and so the spc was the main theme. At the end of September, two Typhoons (Nos 19 & 20) hit us, but in October the weather recovered rather fine. In mid-Oct, the angular diameter δ reached 15". (As anybody remembers, the planet Saturn showed, after a cycle of thirty years after, a big white oval which was detected by ISHADOH (Id) and WAKUGAWA(Wk) in Okinawa on 1 October, and the discovery was readily communicated to MIYAZAKI (My) to take a set of TP photos in an earlier stage.)

In November (λ=326°Ls~342°Ls), 500 observations were produced by the domestic observers. N Alcyonius, Gyndes and Propontis I were all caught, while everybody felt it not easy to detect Iuventæ Fons compared with the case in 1988. A detail of Nilokeras was still easy. In December, according to Id, the weather in Okinawa turned to bring just like a summer seeing to produce good results (see below). On the new year day in 1991, the Martian was near the southern autumn equinox λ=358°Ls with δ13". (This time, on 1 January 2006, the season will read λ=350°Ls and δ12.1".) Iw observed by chasing the nph until March 1991. At Fukui, the final observation was made by Nj on 7 May 1991 when δ=5", λ=057°Ls, φ10°N.


 2°  The first Dust: Even after the so-called season of the great dust storm (at those times we set the deadline to be around λ=200°Ls~ 250°Ls), no great dust disturbance started. Eventually no southern great dust storm was found in 1990. The rainy season at the Hokuriku district (including Fukui and Noto) ended on 20 July, quite normal, but the coming summer proved to be a real hot summer, and it was reported the Biwa Lake at Otsu, the largest lake in Japan, suffered from the shortest of water since 1939. The Solis L area was well observed from the breaking period of the rainy season and showed us three times until the opposition time. At the beginning of October, the central latitude went downward to φ3°S: The spc was thus all the more difficult to observe, but it was quite clear at the latter part of October for the period λ=317°Ls~321°Ls under good seeing.

On 4 October (λ=310°Ls), Don PARKER (DPk) and Jeff BEISH (JBs) detected a dust disturbance from Chryse to Eos (IAUC #5116, see also BEISH’s LtE on 6 October: CMO #095 p0808). This dust disturbance must have been one of the dusts which originated from the northern district around the nph, as is recently the well-known topic of discussion about the MGS results. The aftermath was not clear at that time however, whether it dispersed before it faced to us or not. See a detail in RMk’s article cited below. Just note the Martian season was λ=310°Ls similar to the MGS cases.


3°  Activity of the nph: At the end of October, the nph was observed very disturbed at the area of M Acidalium. The present writer’s continual observations from 20 October to 23 October (λ=320~321°Ls) were shown in a schematic figures with 4×6 partial drawings in CMO#096 at p0816. This set of figures was also reproduced in Mn’s article in "Sky Watcher' Handbook" (edited by J MUIRDIN, published by Freeman, Oxford, 1993). Here we cite a drawing on 22 October (λ=321°Ls) at ω=030°W, φ=04°S, δ=16.1". A part of M Acidalium was seen trough the nph, but this was not stable. It is still amazing to see the sketchbook at that period which shows well realistically a Sturum und Drang of the nph around M Acidalium. There seem to exist sometimes outbursts to the southwards from the edge of the nph, and they suggest a role played by the dust. It is thus important to chase the npr from λ=310°Ls (as pointed out by Christophe PELLIER (CPl), private communication, the December dust in 2003 must have also been originated from the higher northern latitudes at λ=315°Ls), while in 2005 unfortunately the central latitude does not go down beyond φ=11°S: when λ=310°Ls (21 Oct) onward, φ13°S or southward. However the angular diameter δ is about 20", and it may be easier to watch the area of Chryse itself. In Japan, Chryse will face to us at midnight as November begins.


4°  Second Dust: On 2 November 1990 (λ=326°Ls) there was reported an observation of a dust near Auroræ S in Italy, T PLATT in England took clearly its ccd image on 3 November, and it was chased well in Europe. This is detailed in the aforementioned RMk’s report (whose summary was made in CMO ##112 and 124), and finally a complete narrative of RMk was given in his masterpiece: Memoirs of the BAA, vol 44 (1999) Telescopic Martian Dust Storms; A Narrative and Catalogue (pp112~115). If we see the diagram and the original ccd images (at the Pic du Midi) made on 6 November (λ=329°Ls), the dust was clearly seen also in the northern hemisphere, and hence it is quite possible it was also originated in the higher northern latitudes though observations were lacking.

According to the catalogue of RMk, there occurred three dust storms in 1990, and the final was also observed in Chryse during 4 December (λ=344°Ls)~16 December (λ=350°Ls). At any rate, the season from λ300°Ls to 350°Ls is very important.

Writing up this way has inclined the present writer (Mn) to think that der Sturum und Drang at the end of October of the nph must have possibly been a precursor of the Chryse-Eos dust disturbance at the beginning of November. At that time we never dreamt such a relation, but in view of the northern originating dusts, it is quite natural to think it is quite possible. On the day of 2 November (λ=327°Ls) when the dust was observed in Europe, the present writer observed starting from ω=242°W (14:20GMT) to 19:40 GMT (4:40 JST) at ω=320°W when M Acidalium was just coming up. On 3 November MIYAZAKI (My) also took a set of photos at ω=317°W at 20:15 GMT (5:15 JST), but no further. The nph was strong as well. Unfortunately there still lies a vast vacant region from Japan to Europe.


5°  Tharsis Ridges: The cloud behaviour of the Tharsis ridges as well as Olympus Mons before the opposition is an important objective to record: In 1990, the second peak at around λ=310°Ls of the cloud activity of Arsia Mons was clearly caught by MIYAZAKI (My) on 13 October (λ=315°Ls) at ω=095°W, 123°W and on 18 October (λ=318°Ls) at around ω=110°W. One month later, it was quite near opposition, but those Int, R and B shots by My were precious made on 18 November (λ=335°Ls) and 19 November. Arsia Mons now ceased to be less active than the previous case (as well as at λ=280°Ls in 1988) and showed the activity was minimal. Olympus Mons, without cloud, looked evident however weaker than the case in 1988. In 2005, the region will be seen around from the end of October at λ=315°Ls in Japan (in the US in mid-October), and we should pay our attention to the area. It is just before opposition. One month before we should be on alert from the mid-September in Japan around λ=290°Ls (in the US at the beginning of September, and in Europe at the beginning of October). The second minimum will visit however after opposition, and so it will be rather difficult to prove (the first minimum is at λ=225°Ls~230°Ls while the angular diameter may be too small to prove (δ=8")).


6°  Miscellaneous: The area of Solis L appeared in 1990 to be the same as in 1988 and 1986. Such a marking as Phasis was caught easily for example on MURAKAMI (Mk)’s TP photos taken by the use of a 10cm Nikon refractor (Mk secured 20 photos in October and 25 photos in November by the same object grass).

The apparition was suited to chase the final state of the spc, while it depended on the weather and the facing longitude of the central meridian. At Fukui, the watching of the spc was only up until 21 November ~ 23 November (λ=338°Ls) where we could watch ω=020°W ~ 080°W. Next occasion when we could catch the region came at the end of December, and already δ was under 15". In 1988, My and other chased it until λ=340°Ls.

After October 1990, (we should say after λ=325°Ls in Japan), there was observed a strange cloud broad belt form the southern bottom of Hellas towards southward, while Zea L was apparent. This was also evident in December and even after the southern autumn equinox (λ000°Ls). It is expected to record further observations. In December, after Hellas came into the disk there observed a few thick cloud patches near the morning terminator: These were quite apparent on B photos by My and AKUTSU (Ak) on 6 December (λ=345°Ls) and so on.


7°  Finally: we note the above description heavily depended on a review by NAKAJIMA and MINAMI Mars Observations in 1990/91 published in Bulletin of the Fukui City Museum of natural History No. 40 (1993). Of course some of the CMO paper versions were referred.

To sum up, der Sturum und Drang at the northern hemisphere after λ310°Ls should be important to be watched, especially to the north of Chryse and Utopia. In these cases the ccd imagers should shoot the area every 20 minutes to grasp the delicate motions of the cloud. The B ingredient is particularly important. As to a possibility of the southern dust storm around λ300°Ls as in 1973, we shall review in a following article (the global dust storm in 1894 was on set possibly just before λ300°Ls).

In 1990, it was cloudy in Fukui both the day (20 November) at opposition and the day (27 November) the planet was closest to the Earth. CMO #098 informs it was all the same all over Japan. However at the later fortnight in November it was fine for more than seven days. In December, the first ten days were good. On 7 December, Iw’s sketch reached No 209 the season which corresponded to his 1000th drawing ever since he became a serious Mars observer in 1984. On the note of the next drawing, watching the Huygens crater he wrote this may be the last moment to see Grace’s Fons, and I may not be able to see it until the 21 Century. Was it so?

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