Forthcoming 2007/2008 Mars
(7)
The
Seasons of Dusts
CMO #331 (25 May 2007)
Masatsugu
MINAMI
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n the coming 1st day of June 2007,
the Martian season reaches λ=249°Ls. It was at λ=250°Ls that the
Noachis great dust storm spectacularly broke out in 1956, and so we should say
the season of great dust storms has arrived. Note however that since then no
Noachis dust storm has been seen at the same season, and if there arose a great
dust storm it has chosen quite a different time (so if we borrow Don PARKER (DPk)’s words, it is quite natural for Mars to foil us).
Even then we have been obliged to watch the place at the season and this time
also we can not help watching. We cannot say it has meaningless to check
whether it will occur or not. The dust activity must be a kind of catastrophe
which arises when a consistence of a certain income and outgo is broken, but
its catastrophe and feedback must not simply follow the solar calendar since
Mars is not dead as the Moon. However the season of Mars is not irregular as
Jupiter’s, and so it does not make any wrong if we say the season of dusts has
set in.
On the other hand, this apparition proceeds
very slowly until the opposition time, and on 1 June the apparent diameter δ
is only 5.7". One may be afraid that, in addition to the low altitude of
the planet in the morning sky, such a small diameter will make it impossible to
find and chase the dust cloud. However the fact that such images as were
obtained by BUDA (SBd) and HEFFNER (RHf) from 23 April (λ=225°Ls) to 30
April (λ=229°Ls) when δ=5.2"~5.3" clearly show the dark area
of M Serpentis tells us easily that such a bar-like dust as observed in 1956
and 1971 cannot be missed to be recorded even when δ=5.7". By naked
eyes it may be hard in general to detect the dust disturbance if the diameter δ
is under 10", but ANTONIADI once detected the disappearance of S Meridiani
because of the dust covering when δ=7.5". This was of course made by
the use of the Grande Lunette at Meudon, but it must be doubtless such an
outstanding case will be caught by the present-day ccd
technique, and even by the naked eyes it may be possible since the place is
very characteristic if used a medium sized telescope. This discovery was just
said made in January 1925 in his book: La
Planète Mars, p92, but at p126 he describes that the
Lunette showed him as if S Margaritifer was protruding from the terminator due
to an orange cloud mass over there on 18 Jan 1925, and so the cloud on
Meridiani S must have been related with this. Then the season must have been
around λ=335°Ls. In 2007 this comes at the end of October with δ=11.4".
In 2005,
The
reason why we should not disregard the dust appearance even when the angular
diameter is tiny is because the early dust disturbance may cause or have a
relation with the further big disturbance later. It is well known that in 1971,
the big 1971b great dust storm followed the preceding small 1971a dust. More
serious case was in 1973: In 1973 the great dust storm occurred at λ=300°Ls
and it is believed that this dust was given rise to by the temporary large dark
marking at Daedalia which was extraordinary and appeared in early 1973 or
before. Apparently this temporary dark albedo marking
must have been caused by another preceding dust disturbance. Unfortunately this
dust disturbance was not identified. In the case of Shotaro MIYAMOTO, Kwasan
Observatory,
The rare example which we witnessed when the
dark marking was produced by the dust disturbance is the case at M Serpentis in
July 2003 (λ=215°Ls): The dark marking readily showed up as the dust
subsided. In the case of Daedalia in 1973, we can suppose a much brighter dust
must have occurred around there, and so it could not have been missed even if
the diameter was smaller. By the same token, at present the area of M Serpentis
is a live spot to be watched as well as Deucalionis R.
So we
here, in order to give a guiding table, pick out some of data accumulated by
the forerunners as a function of the coming season.
In ANTONIADI’s book, there is shown a figure
showing his observations in 1909 on 23, ~27 August by the use of a 22cm spec
(p40): The figure shows a vast yellow cloud which covers the northern
hemisphere from the area of Trivium Charontis to the morning side. The season
was around λ=258°Ls~260°Ls. This corresponds to mid-June 2007. ANTONIADI
also writes that M Cimmerium is covered often by the yellow clouds which deform
its shape or make it disappear, and among several examples, he picked out the
case on 22, & 23 Aug 1909 when it was considerably pale (p174), and so this
must have been an influence of the dust cloud just mentioned. He also writes
that in August 1909 he certified (with QUÉNISSET) that Syrtis Mj was also virtually invisible near the CM covered by the
lemon yellow cloud (p86) by the use of a 24 cm at Juvisy. (It
was from 20 September 1909 that ANTONIADI used the 83cm refractor at Meudon.)
At the beginning of September 1909, he also certified that Solis L disappeared because
of dust covering (p142), and this was also the influence of the same dust
event: This must have been just before λ=270°Ls. In 2007, the period λ=260°Ls~270°Ls corresponds to the term from the end of
June to the beginning of July.
The moment λ=260°Ls was the one the
great dust storm was entrained at Noachis in 1971 (1971b). This case also has
never repeated since then, but as the dust season it is well matured. In 2007
it occurs in mid-June. λ=260°Ls is realised on 18
June, and can be seen in Europe to the
When
the planet Mars was most approaching the Earth in 1924, ANTONIADI observed
consecutively five days from 10 to 14 October 1924 at Meudon, and made several
observing notes. Among them, he observed on 12 October (with QUÉNISSET) that
the coming Syrtis Mj was not perceived since it was covered
by a greyish yellow cloud mass (p86). The season
might have been around λ=277°Ls, and so we should a bit remember this in
mid-July 2007.
The aforementioned ANTONIADI’s description of
the yellow clouds at M Cimmerium was mainly concerned with the case during the
period from 10 Oct to 31 Oct in 1894: Since it was seen at the opposition time,
there were joined a lot of observers including FLAMMARION. BARNARD at Mt
Hamilton was another. BARNARD suspected a presence of the dust from September,
and he reported it continued until 28 Oct on which day M Cimmerium quite
recovered. His drawing on 22 October shows a queer aspect of the region. Here
we employ the date 10 Oct according to
ANTONIADI, while in the Tome II of FLAMMARION’s book:
The Planète
Mars, there is shown a fine drawing by QUÉNISSET made on 20 September 1894
in which a dust core is shown to the south of the faint M Sirenum and this
might have been related with the Oct dust. This was made by a use of 17cm
refractor, but amazingly QUÉNISSET detected the spc
to have been split into two (this was observed by BARNARD on 7 October by the big
Lick refractor). The season was around λ=285°Ls. The period 10 Oct ~ 28 Oct might have been
corresponded to λ=298°Ls ~ 308°Ls, and in 2007 the period will be realised from 19 Aug (δ=7.6") ~ 5 Sept (δ=8.5").
Incidentally this 1894 Oct cloud was also
observed by
As
mentioned, the great dust storm in 1973 occurred at λ=300°Ls. This 2007 year
the season will visit around 23 August with δ=7.8". Because Daedalia
has been bright ever since except for a presence of Phasis,
no serious dust has been observed, but in 1973, there were known several small
dusts since the time MIYAMOTO started till λ=300°Ls, and also in 2005
there occurred a Solis L active dust on 21 Oct 2005 at λ=310°Ls, we should
be careful.
After
λ=300°Ls, we must be attentive to the so-called cross-equatorial dusts
which originate from the northern hemisphere. As noted in CMO #289,
http://homepage3.nifty.com/~cmomn3/289Note02_03/index.htm
the second period of the north originated dusts
is around λ=300°Ls~350°Ls (while the first one is around λ=210°Ls~230°Ls),
and it is possible for some of the dusts to propagate to the southern hemisphere.
The October 2005 Solis L dust at λ=310°Ls belongs to this kind, as well as
the December 2003 dust detected by DPk at λ=315°Ls. So after λ=300°Ls, that is,
after mid August in 2007, we should be careful to the dust from the area of M
Acidalium as well as from the area of Utopia.
Now
there is known a great dust storm in 1924 which was similar to the Noachis dust
storms in 1956 and 1971: It was Dr McKIM (RMk) who
unearthed some drawings of Rev PHILLIPS and others on 9~10 December 1924
showing a dust germ which broke Hellespontus near the
CM. The season was around λ=313°Ls with a diameter of 10", and it developed
to a great dust storm. In ANTONIADI’s book there is shown a drawing on 31 December
1924 where the surface was vastly covered by the dust except for the shadowy
crest of Olympus Mons. This was at λ=325°Ls, and so it lasted long. In 2007, at λ=310°Ls δ is under 8", and as stated comes
around 8 September. On the other hand λ=325°Ls implies the beginning of October 2007.
In
ANTONIADI’s book at p41, there is a chart where it is shown there was a large
dust storm on the southern hemisphere in 1911 from 3 November to 23 December (à). The season was around from λ=325°Ls ~
355°Ls with the diameter around 17" before opposition. The dust on 3
November was already large and so it started earlier but not trapped because of
no observation in Asia (the systematic Mars observation in
Incidentally the present writer (Mn) is of the opinion that the southern hemisphere in 1879 was also
largely covered by the big yellow cloud as in 1911. This belief is based on the
fact that SCHIAPARELLI faintly drew the southern hemisphere compared with the
northern coasts of the central dark markings on his Albedo Map in 1879
(see the
Tome I of FLAMMARION’s book at p332-p333), and there is also at least one drawing
where the southern hemisphere is made very blank. In 1879 the planet was at
opposition on 12 November (quite similar to the 2005 case: On 11 November, he
spotted the shining Olympus Mons before noon), and the season he observed from
September 1879 to March 1880, and produced the Map based on 30 complete
drawings and 104 numbers of partial sketches. Here a part of the Map is copied
from the Mimesis Edition of “La Vita sul Pianeta Marte”
of SCHIAPARELLI (which book was given to Nj at Brera). Click the lhs Figure to see a larger one. The strange shape of the S Sabaeus and the dusty Deucalionis R must have been based on
his drawing on 28 November, and so the dust phenomenon was going on at the
season λ=335°Ls and so the situation was quite similar to the case in 1911
(including the fact that the date of the start is unknown). 1911 = 1879 +15+17.
We have thus picked out some of interesting
dust phenomena on the southern hemisphere, and eventually the season of dust is
revealed to last without a break this year. However, as we have stated first,
any dust occurrence don’t necessarily follow the rut left by the preceding dusts,
and so a list is a list, and there are naturally Martian years where no big
dust disturbance does not occur. Originally the dusts frequently occur when the
balance of income and outgo is broken, but when the energy-balance is kept long,
the big catastrophe is difficult to occur (as around in 1990). But recently
there seem to be observed occasional changes in global albedo,
and so the balance of energy looks a bit excessively in the red or black. So we
should be careful this year.
To sum up, here is a Table which shows
possible period of dust seasons in 2007, but not perfect.
|
A |
B |
C |
D |
E |
|
λ=250°Ls λ=258°Ls λ=260°Ls λ=277°Ls λ=285°Ls λ=298°Ls λ=300°Ls λ=310°Ls λ=313°Ls λ=315°Ls λ=325°Ls λ=330°Ls λ=335°Ls |
Noachis Elysium Noachis Syrtis Mj Phaethontis M Cimmerium Solis L Solis L Noachis Chryse Southern H Southern
H |
Aug 1956 Aug 1909 Sept 1971 Oct 1924 Sept 1894 Oct 1894 Oct 1973 Oct 2005 Dec 1924 Dec 2003 Nov 1911 Nov 1879 Jan 1925 |
b. June m. June 18 June m. July 29 July Aug-Sept 23 Aug b. Sept 13 Sept m. Sept Oct-Nov Oct-Nov e. Oct |
AO AO E,A E AO All A AO AO AO All All AO |
A: The season
when the dust started
B: The area
where the dust started
C: The period
when the dust started
D:
Corresponding period in 2007
E: Possible
terrestrial region where the corresponding area can be seen
Abbreviation: b.=beginning, m.=mid, e.=end of the
month
AO: Asia-Oceania, E:
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