Forthcoming 2007/2008 Mars
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Mars in 2007/2008. II

CMO #336 (25 September 2007)

Masatsugu MINAMI, Masami MURAKAMI and Akinori NISHITA


 


 

20 As already stated in I in CMO #325 (25 November 2006) the planet Mars in 2007 will be closest to the Earth on 19 December 2007 at 00h GMT (with maximal angular diameter δ=15.9"), and at opposition on 24 December 2007 at 20h GMT, and so the latter half of the apparition occurs in 2008. And so as a sequel to I, we shall here be concerned with possible observational points in 2008.

 

21 At the beginning of 2008, the planet Mars is going backward and stays at the eastern part of Tau. On 7 January (λ=014Ls) its apparent declination reads the northernmost value (D=2659'N), and Mars shines very high up (about 80 degrees high) from our lands. On 30 January (λ=025Ls), its motion becomes stationary, and then resumes going eastwards. On 30 March (λ= 051Ls), the planet attains the eastern quadrature with a diameter under 7 arc seconds and henceforward the planet is to be observed in the evening sky.

 

22 As was shown in the first figure in I (CMO #325) (or see also a figure at page Ser2-0541 in CMO #327), the angular diameter δ rapidly decreases after opposition (more rapidly than the time it approaches). On 1 January (λ=010Ls), the δ is 15.4", and well large, but on 20 February (λ=034Ls) it goes down to δ=10", and on 1 June (λ=079Ls) further down to δ=5". The apparent declination will goes to the southern sky at the end of August with δ=3.9". The conjunction with the Sun occurs on 5 December 2008.

 

23 The observable season in 2008 is so from around λ=010Ls to λ=105Ls (the end of July when δ=4.1").

 

24 At the beginning of 2008, the activity of the north polar hood (nph) is still expected, and so such a phenomenon as the Dawes Slit may be observed. The north polar cap (npc) must attain the largest size at around the spring equinox (λ=000Ls), but afterward the activity of the nph will be weakened and the dark fringe of the npc may peep out through the nph (especially at around Gyndes canal at Ω=180W). To witness the moment when the npc pops out, one should be attentive from λ=010Ls to 020Ls.

25 The observation of the recession of the npc is an interesting and important problem of the present and following apparitions. We shall detail this problem in a coming issue: Around λ=050Ls when the so-called Baum's plateau comes to an end, the northern hemisphere will become to well face to us (at the end of March, the tilt will turn to be φ=4N~5N).

 

26 The ccd images may catch some dusts inside the npc. On 18 September 1996 (λ=011Ls) and on 15 Oc-tober 1996 (λ=024Ls), the HST witnessed the dust

streak from the inside of the npc to the edge side. More recently the MGS-MOC proved an existence of an envelope front of the dust inside the npc on 7 August 2004 (λ=071Ls) - see Christophe PELLIER's colour mosaic cited on page Ser2-0615 (CMO #330). All are within the season in 2008.

 

27 Some dust protrusions from the north polar region (npr) may also be expected this season. On 29 August 2000 (λ=042Ls) the MGS caught a dust burst which protruded outwards from the edge of the npc. In 1963 on 1 February (λ=049Ls), T SAHEKI and S MIYA- MOTO observed at the same time some dust streaks from the npr which curiously crossed Sabaeus S.

 

28 After the spring equinox, the water vapour caused by the thawing of the npc will go southwards and on the way generates some ascending evening clouds at the higher mountains. Especially this kind of cloud will be conspicuous from λ=060Ls, at Olympus Mons, Pavonis Mons, Ascraeus Mons and Elysium Mons. These cloud may be detected even if the angular diameter decreases. Arsia Mons is slightly different: the evening ascending cloud will be seen but the best time will be after the end of the season.

 

 29 We also note that in 1993 on 12 February (λ=039Ls) Y MORITA detected a large bright patch (maybe dust) from Elysium to Cebrenia (see CMO #140, 25 Dec 1993 issue). In 1995 at the end of January (λ=051Ls), M MURAKAMI and T IWASAKI and others observed a bright patch (maybe a white cloud) at Alba (CMO #179, 25 Sept 1996 issue). Alba behaves like Olympus Mons and so any should be attentive on this area also this season.

 

30 Finally we note that Hellas now enters a different phase. After a while from the southern autumnal equinox, the Hellas basin becomes covered by frost or is icebound. So we should be attentive to Hellas around from λ=060Ls. Seasonally its behaviour looks akin to the evening ascending cloud of Olympus Mons et al but by a very different reason. At the end of the present apparition at λ=100Ls, it will shine near the southern limb because the tilt is around φ=25N, and so some may confuse it with the spc.

 

31 Occultations of Mars by the Moon occur on 20 January, seen from N Russia, Arctic regions, NW tip of N America, on 12 April, seen from NE Canada, Greenland, Iceland, N Scandinavia, on 10 May, seen from N Africa, Europe except N part, and S Asia, and on 8 June, seen from New Zealand. None from Japan. Mars passes by ε Gem on 30 March, by α Leo on 1 July. The planet Saturn approaches Mars up to 0.7 on 11 July. On 24 May, the planet Mars proceeds through the Prsepe Beehive cluster (M44).

 


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