Forthcoming
2005 Mars
(2)
Mars in
2005
Masatsugu
MINAMI, Masami MURAKAMI and Akinori NISHITA
1°
The
2005 Mars, its angular diameter δ being 4.2 arcsecs at the beginning of
2005, is predicted to be closest to the Earth on 30 October 2005 (at 3:26 GMT à la J Meeus) with the maximal angular
diameter of δ=20.17 arcsecs as follows:
closest
λ 315.2°Ls
φ 14.3°S
δ 20.17"
magnitude
- 2.3 degrees
distance 0.46406 au
69.42 million km
Position
(RA: 03h02m,
App Decl: +16°14' (2000.0))
The closest distance in 2003
was 0.37272 au or 55.76 million km, and so this year the closest planet is more
away by about 14 million km.
The
opposition occurs this year after the perihelion, and so after the day the planet
is closest: The planet will thus be at opposition on 7 November at 8h GMT with Apparent Decl=+15°54'.
The rate of increase of
the angular diameter at the first half of the year is rather slow, and it is
not until mid-July that δ reaches 10 arcsecs. After opposition, the
diameter will decrease rather rapidly and goes down to δ=12.2" at the
end of 2005.
When the planet is near
at opposition, it will shine in Aries
so that its apparent declination is near +16° as noted above and so the
altitude of the shining Mars at meridian is higher by about 30° than that of
the 2003 planet when it was closest if seen from the standpoint of the
observers in the northern hemisphere. We shall repeat, but the approach during
the first half of 2005 is more asymptotic or slower until the altitude of the
planet in the northern sky will become more favourable. In early February, it
shines very low around with App Decl=
-24° at Sagittarius, and then the
planet will cross the celestial equator from south to north at the end of June,
and further ascends northward to +5° at Pisces
in summer, and will pass the western quadrature on 12 July. The apparent
diameter δ, after it passes δ=4.2” with λ=137°Ls at the beginning of 2005, gradually
reaches δ=10” around 14 July; and so we may say the first favourable time
for the northern observers would come in mid-July. The Martian season λ in
mid-July is near 250°Ls where Ls denotes the Areocentric Longitude of
the Sun. Somewhat by coincidence, it is the season
when the 2003 Mars was near at opposition. Furthermore it is the memorial time
when the 1956 global dust storm was entrained. The apparent diameter then
reaches δ=15” around on 10 September. The data in 2005 are thus made into
a Table.
|
Western
quadrature |
12
July |
δ=10.0” |
λ=247°Ls |
|
at
perihelion |
17
July |
δ=10.3” |
λ=250°Ls |
|
Stationary |
1
Oct |
δ=17.8” |
λ=298°Ls |
|
closest
approach |
30
Oct |
δ=20.2” |
λ=315°Ls |
|
Opposition |
7
Nov |
δ=19.9” |
λ=320°Ls |
|
Stationary |
12
Dec |
δ=15.1” |
λ=338°Ls |
Here we shall go in some
details to compare the Martian season and the status of the 2005 Mars with
those in 2003 and /or 2001.
As
is suggested by the Figure at the left-hand side, the maximal δ (=20.2”)
in 2005 corresponds to the angular diameter we experienced in 2003 around on 20
July and/or on 3 October, and so we may say the 2005 apparition is similar to
the 2003 case where a period of about 2.5 months from the latter part of July
2003 to the beginning of October 2003 are completely missed. The diameter of
20.2 arcsecs implies to be smaller than the maximal diameter in 2001, but it is
still larger than the case in 1999. The above figure suggests however another
important characteristic of the 2005 apparition to be noticed: the peak of the
diameter comes quite at different Martian season. The apparent diameter δ
in Fig 3 is a function of the Ls, and
so apparently the 2003 Mars showed us well the surfaces of Mars before the
summer solstice of the Martian southern hemisphere (λ=270°Ls), while the 2005 Mars will provide us
the season from the southern summer solstice to southern autumn equinox
(λ=360°Ls (=000°Ls)). At opposition the 2005 Mars will
attain the season of λ=315~320°Ls,
so that we can watch better the seasons around this λ=310~325°Ls, while in 2003, this season visited
in mid-December so that the δ was less than 10 arcsecs. So from the point
of view of observing the Martian season, the 2005 apparition is very
supplementary and our continuation of observations is indispensable.
It is also interesting to
notice the intersection point of the 2001 and the 2005 graph. It is near the
perihelion, and this implies that we can observe the season at λ=250°Ls in 2005 under the condition similar
to that in 2001. Just the defect of illumination must be at the opposite side.
We thus say we can observe the season symmetrically three times successively in
2001, 2003, and 2005.
2°
As stressed in the
preceding section, it is absurd to regard the 2005 apparition is inferior to
the 2003 apparition. They are both equally important with respect to the
observations of the Martian seasons, and in some respects the 2005 Mars shows
unrivalled points.
As suggested, the
apparent diameter δ becomes larger than 15 arcsecs around 8 September 2005
when the season λ reaches 284°Ls.
Since our recent Martian observations aim at the Martian meteorology as a
function of the season, this value implies something dividable.
In
2003, δ proved to have been already near 16.1 arcsecs when the Martian
season attained 286°Ls. The δ was
further down to 15 arcsecs when the season reached λ=290°Ls, so that in 2005 from around
λ=290°Ls, the 205 Mars will
surpass the conditions in 2003.
On 30 October, when δ=20.2, the season
reaches λ=316°Ls as repeatedly
noted, but in 2003, at λ=316°Ls
the δ was no larger than δ=9.8". The season λ=290°Ls will arrive on 17 September, and the
day is the beginning of new era.
The south polar cap
(spc) is already at the minimal state at λ=290°Ls. The 2005 apparition provides the last opportunity in the present
cycle to be able to observe the total regions of the southern hemisphere: In
fact, after March 2005, the tilt of the north pole will go away from the Earth
and the central latitude φ (=DE)
keeps φ=14°S even when the planet is near at opposition. So this is the
best chance to watch the final/residual state of the spc beyond λ=310°Ls. It should be remarked that after
λ=235°Ls (around at the end of
June in 2005) the centre of the spc will deviate from the south pole towards
the direction of Ω＝030°W,
and the appearance of the final state of the spc is
variable according as the CM varies.
There are several
phenomena characteristic or just observable in the season which we encounter in
2005. For instance the minute aftermath of the detachment and vanishing of
Novus Mons is a subject of observation. At the same time of the observations of
the inside of the spc as well as its periphery, the high latitude continents
and dark markings should be carefully observed: For example in 1990 the region
of Hellas showed a strange light and shade partly misted during the period
λ=320~330°Ls. Eridania also
behaved interestingly in 1990. Interesting is also the observation of the
Tharsis ridges and Olympus Mons when they are in the afternoon. The evening
orographic cloud over the summit of Olympus Mons ceases to be active around
from λ=200°Ls (in 2005 around on
26 April), but the three Montes at Tharsis are different (also different among
them), and the cloud over Arsia Mons continues to be active and makes another
smaller peak from λ=250°Ls to
λ=330°Ls, namely the period when
the planet is before and near at opposition. The Arsia white cloud was not
observed at this season in 2001 because of the presence of the yellow cloud. So
the white cloud must be sensitive to the mixture rate of condensate and dust.
The summit of Olympus Mons should be watched carefully when it becomes near the
terminator or limb. These should be checked by the use of the genuine Blue
filter.
Even if the season after
λ=290°Ls is very own with
respect to 2005, we should also pay our careful attention to the season before
that because the Martian season is not a simple repetition. The time of
occurrence of the dust clouds is different from year to year, and we should be
on alert concerning the yellow cloud around from λ=200°Ls (at the end of April) though δ
is still smaller with 6.5". The spc begins to thaw rapidly around from the
time.
Rather unfortunately,
the 2005 Mars will not provide well the information about the north polar region (npr), but we should pay attention to the
activity of the north polar hood (nph) in relation with some possible dust
disturbances. It was reported in 2002 the MGS cameras caught several dust
outbursts near the northern high latitude region during the very season from λ=315°Ls to λ=350°Ls (http://www.msss.com/mars_images/moc/weather_reports/
). In this sense, M Acidalium and Utopia are the regions attentively watched in
2005: As well Chryse and the area from Neith R to Ætheria are the important
gates concerning the npr dust/condensate cloud
information. Since Chryse played frequently a special role in entraining the
dust disturbances in 2003 (especially the December 2003 significant dust
occurred at λ=315°Ls), we should
be attentive about this particular region.
The last but not the
least, we should call attention a bit to a possibility of the reflection flare
occurrence in 2005. The 2005 Mars is akin to the 1958 case, and so the Solis L
area is still a candidate. Geometrically the coincidence of DE and DS
will occur around 8 November when the apparent diameter is still of
δ=19.9". Refer to a detail in another article which we shall
translate soon from the Japanese edition.
3°
Finally we try to mention
about the observation cycle and stress that the observation of the Martian
season is now a principal object of the Martian observations.
The planet Mars
approaches to the Earth every two years and two months and then away, and every
apparition the planet shows us a different season in Ls to us with a different maximal diameter. So in order to observe
the whole Martian season in a favourable condition it will need exactly seven
times of apparitions or 15 or 17 terrestrial years. During the period, there
are several apparitions where the maximal angular diameter is below 15 arcsecs,
and in those periods we (the northern observers) are under the cold winter
season. However these apparitions also are important for us to gather the data
about the seasonal meteorology on Mars.
Yes the present day
observation of Mars is for the observations of the atmospheric phenomena on
Mars and nowadays the effort just to detect the details on the Martian
topography has been very out of date. However it is important for the observers
to be acquainted with the fundamental dark or bright markings on the planet
since the diurnal variations and/or the annual variations, and/or furthermore
the secular changes can be observed with reference to the fundamental marking
configuration on Mars. In any scientific work, repetition or comparison is a
key word: the true difference (or even differentiation in mathematics) can be
established based on a rigid comparison (or a reference frame in mathematics)
and if the comparison frame is fragile, any assertion cannot be proved. In real
observations of Mars, the repeated comparisons of the surface with the same
surface on the preceding days are the least requirement of the wise
observations. A repetition day by day of observing the same surface from the
same angle, even if boring, is one of fundamentals.
If one wishes to compare
the surface on the day with the surface appearance of the day before one should
have prepared the observation 40 minutes earlier than the day before.
Conversely speaking to find the same surface as the surface one observed the
day before, one have only to observe 40 minutes earlier than the time one
observed the day before, because the rotation of Mars is longer than the
rotation of the Earth by about 40 minutes (exactly 41.3 minutes longer, while
the rotation of Mars is 24h37m26s: more exactly speaking we must further take
account of the every-day mutual motions). If we repeat this consideration, we
are easily led to the following axiom: To prepare the documents enough to cover
all the cases, we should observe every 40 minutes every day at fixed times. The
planet rotates nearly 10 degrees every 40 minutes, and so if we observe every
40 minutes, we are to have a series of images each of which are separated by 10
degrees and its multiples. The following tables show how we shall get the
series of ω (=Longitude of the
LCM seen from Asia and Oceania
|
GMT |
12:20 |
13:00 |
13:40 |
14:20 |
15:00 |
15:40 |
16:20 |
17:00 |
17:40 |
18:20 |
19:00 |
|
27 Oct |
068°W |
078°W |
088°W |
097°W |
107°W |
117°W |
127°W |
136°W |
146°W |
156°W |
166°W |
|
28 Oct |
059°W |
069°W |
079°W |
089°W |
098°W |
108°W |
118°W |
128°W |
137°W |
147°W |
157°W |
|
29 Oct |
050°W |
060°W |
070°W |
080°W |
089°W |
099°W |
109°W |
119°W |
128°W |
138°W |
148°W |
|
30 Oct |
042°W |
051°W |
061°W |
071°W |
081°W |
090°W |
100°W |
110°W |
120°W |
129°W |
139°W |
|
31 Oct |
033°W |
043°W |
052°W |
062°W |
072°W |
082°W |
091°W |
101°W |
111°W |
121°W |
130°W |
|
01 Nov |
024°W |
034°W |
044°W |
053°W |
063°W |
073°W |
083°W |
092°W |
102°W |
112°W |
122°W |
|
02 Nov |
015°W |
025°W |
035°W |
045°W |
054°W |
064°W |
074°W |
084°W |
093°W |
103°W |
113°W |
|
03 Nov |
006°W |
016°W |
026°W |
036°W |
045°W |
055°W |
065°W |
075°W |
085°W |
094°W |
104°W |
|
04 Nov |
358°W |
007°W |
017°W |
027°W |
037°W |
046°W |
056°W |
066°W |
076°W |
086°W |
095°W |
|
05 Nov |
349°W |
359°W |
008°W |
018°W |
028°W |
038°W |
047°W |
057°W |
067°W |
077°W |
086°W |
|
06 Nov |
340°W |
350°W |
360°W |
009°W |
019°W |
029°W |
039°W |
048°W |
058°W |
068°W |
078°W |
|
07 Nov |
331°W |
341°W |
351°W |
001°W |
010°W |
020°W |
030°W |
040°W |
049°W |
059°W |
069°W |
LCM seen from Europe
|
GMT |
21:20 |
22:00 |
22:40 |
23:20 |
00:00 |
00:40 |
01:20 |
02:00 |
02:40 |
03:20 |
04:00 |
|
|
27 Oct |
209°W |
218°W |
228°W |
238°W |
248°W |
257°W |
267°W |
277°W |
287°W |
296°W |
306°W |
|
|
28 Oct |
200°W |
209°W |
219°W |
229°W |
239°W |
249°W |
258°W |
268°W |
278°W |
288°W |
297°W |
|
|
29 Oct |
191°W |
201°W |
210°W |
220°W |
230°W |
240°W |
249°W |
259°W |
269°W |
279°W |
289°W |
|
|
30 Oct |
182°W |
192°W |
202°W |
211°W |
221°W |
231°W |
241°W |
250°W |
260°W |
270°W |
280°W |
|
|
31 Oct |
173°W |
183°W |
193°W |
203°W |
212°W |
222°W |
232°W |
242°W |
251°W |
261°W |
271°W |
|
|
01 Nov |
165°W |
174°W |
184°W |
194°W |
204°W |
213°W |
223°W |
233°W |
243°W |
252°W |
262°W |
|
|
02 Nov |
156°W |
166°W |
175°W |
185°W |
195°W |
205°W |
214°W |
224°W |
234°W |
244°W |
253°W |
|
|
03 Nov |
147°W |
157°W |
166°W |
176°W |
186°W |
196°W |
206°W |
215°W |
225°W |
235°W |
245°W |
|
|
04 Nov |
138°W |
148°W |
158°W |
167°W |
177°W |
187°W |
197°W |
206°W |
216°W |
226°W |
236°W |
|
|
05 Nov |
129°W |
139°W |
149°W |
159°W |
168°W |
178°W |
188°W |
198°W |
207°W |
217°W |
227°W |
|
|
06 Nov |
121°W |
131°W |
140°W |
150°W |
160°W |
169°W |
179°W |
189°W |
199°W |
208°W |
218°W |
|
|
07 Nov |
112°W |
122°W |
132°W |
141°W |
151°W |
161°W |
170°W |
180°W |
190°W |
200°W |
209°W |
|
LCM seen from America
|
GMT |
05:20 |
06:00 |
06:40 |
07:20 |
08:00 |
08:40 |
09:20 |
10:00 |
10:40 |
11:20 |
12:00 |
|
27 Oct |
326°W |
335°W |
345°W |
355°W |
005°W |
014°W |
024°W |
034°W |
044°W |
053°W |
063°W |
|
28 Oct |
317°W |
327°W |
336°W |
346°W |
356°W |
006°W |
015°W |
025°W |
035W |
045°W |
054°W |
|
29 Oct |
308°W |
318°W |
328°W |
337°W |
347°W |
357°W |
006°W |
016°W |
026°W |
036°W |
046°W |
|
30 Oct |
299°W |
309°W |
319°W |
329°W |
338°W |
348°W |
358°W |
007°W |
017°W |
027°W |
037°W |
|
31 Oct |
290°W |
300°W |
310°W |
320°W |
329°W |
339°W |
349°W |
359°W |
008°W |
018°W |
028°W |
|
01 Nov |
282°W |
291°W |
301°W |
311°W |
321°W |
330°W |
340°W |
350°W |
360°W |
009°W |
019°W |
|
02 Nov |
273°W |
283°W |
292°W |
302°W |
312°W |
322°W |
331°W |
341°W |
351°W |
001°W |
010°W |
|
03 Nov |
264°W |
274°W |
284°W |
293°W |
303°W |
313°W |
323°W |
332°W |
342°W |
352°W |
002°W |
|
04 Nov |
255°W |
265°W |
275°W |
284°W |
294°W |
304°W |
314°W |
324°W |
333°W |
343°W |
353°W |
|
05 Nov |
246°W |
256°W |
266°W |
276°W |
285°W |
295°W |
305°W |
315°W |
324°W |
334°W |
344°W |
|
06 Nov |
238°W |
247°W |
257°W |
267°W |
277°W |
286°W |
296°W |
306°W |
316°W |
325°W |
335°W |
|
07 Nov |
229°W |
239°W |
248°W |
258°W |
268°W |
278°W |
287°W |
297°W |
307°W |
317°W |
326°W |
As seen, since the
rotation period is irrational, the degrees slightly deviate after a while, and
hence every week we should adjust the observing time. In the above cases, if one
wishes to obtain the surfaces which one saw five days before, one should shift
the observation times by 20 minutes. After about 40 days or about 20 degrees in
Ls, the similar surface come around
to recur, and it is good again if one could obtain a series of the surfaces
with the same longitudes to compare.
For the ccd imagers, the span of 40 minutes from one shot to the
following looks too long. If so, one can take the surface pictures every twenty
minutes. In this case one can get two series of images to be compared.
Furthermore, since such a phenomenon as the movement concerning the polar hood
or the polar dust is rapidly variable and so these cases demand a shorter span observations, the every 20 minute
observations are recommended.
(December 2004)