Forthcoming 2005 Mars


LOWELL’s Mars in 1894

Masatsugu MINAMI


he apparition of the 2005 Mars is just the next apparition of the great apparition, and so as far as we experienced it must be akin to the 1990 apparition or to the 1973 apparition. In order to draw up a plan of the campaign in 2005, to look back on these preceding apparitions may be instructive.

Similar apparitions occurred several times during these one hundred years as are they listed as follows (in the order of the opposition days)


 27 Nov 1990   δ=18.1" 

 25 Nov 1911   δ=18.3"

 18 Nov 1858   δ=19.2"

 07 Nov 2005   δ=20.1" 

 04 Nov 1926   δ=20.4"

 25 Oct 1973   δ=21.5"

 20 Oct 1894   δ=21.7"

 10 Oct 1941   δ=22.8"


where δ implies the maximal angular diameter when the planet was closest to the Earth.


 As seen, the 2005 Mars is quite akin to the 1926 apparition (79 years cycle), and further we should say the 2005 Mars lies mid-way between the 1990 and the 1973 apparition. The 1973 Mars should be said similar to the 1894 Mars. The 1941 Mars was particular, and it was quite akin to the grand opposition (opposition making a twin with the 1939 great opposition whose δ was 24.1" ) and has been remembered as the year when Bernard LYOT was active at the Pic du Midi and produced a lot of excellent composite images.


  Here we touch a bit upon the year of the 1894 Mars: Since it was the first year Percival LOWELL planned a Mars campaign at Flagstaff, his observational attitude may be suggestive to us. Percival LOWELL finally left Yokohama on 24 November 1893, and first appeared at Flagstaff on 28 May 1894. He missed the 1982 great opposition, but his plan was beginning around from 1890 through the communications with the Pickering brothers, and really his letter to W H PICKERING in November 1892 is known. According to SHEEHAN’s Mars book (The Planet Mars, Arizona Univ Press, 1996), P LOWELL was presented C FLAMMARION’s La Planθte Mars in December 1893 as a Christmas present from his aunt.


As to the 1894 Lowell Mars, the present writer gave a series of talks at Anamidzu Lowell Conference in May 2004 based on LOWELL’s Mars published in 1895, and also reported about it, and so the following items are no more than a repetition, but here we pick out the least cases that are appropriate to our plan of the 2005 observation. We never here enter into the logics or perspectives of P LOWELL. 


We should first say the observation at Flagstaff in 1894 was well organised. The Mars campaign at the Lowell Observatory in 1894 has the following characteristics: 1) The observers made a team, and 2) the observation period lasted nearly one year. LOWELL thus employed from the outset the method which is suggestive and we should learn. Item 2) implies that the intension of LOWELL was not only to detect the canals or minor markings, but was quite interested in the climatology of Mars. The team of 1) consisted of W H PICKERING, A E DOUGLASS and P LOWELL. It was good that the former two had both already been established as Mars observers, especially they observed the great 1892 Mars at Arequipa, Peru (at an altitude of 2469 m with the use of a 33cm Clark refractor).


The observation was carried from 22 May 1894 to 3 April 1895. During this long period they made a total of 917 drawings. On 22 May 1894, the angular diameter was only about 8 arcsecs, and even then they started the routine observation. We suppose this must have depended on a strong suggestion by W H PICHERING to start their observation from the southern early spring within the period the south polar cap was not so melted away. Note that it was on 28 May that they got into Flagstaff, and really on 31 May LOWELL observed Mars for the first time with PICKERING but with a 30cm refractor, while it was on 1 June that they started to observe by the use of a main 45cm F/17.5 Brashear refractor (the famous Clark 61cm refractor was installed in July 1896, and could not be used in 1894). So we should say Mars arrived before their plan. On 22 May, 24 May, 25May and 27 May they had to use a 15 cm refractor, the one LOWELL once brought into Tokyo, but on 22 May W H PICKERING already found a rift inside the spc and so they were forced to count 22 May into as the first day of their observation period.


As far as our experience was concerned, we checked in 1986 that the centre of the spc began to be shadowy compared with the surrounding brighter torus ring just before the southern spring equinox λ=180°Ls, and as noted again in Report 11 of CMO #276, Parva Depressio was observed in 1988 from 3 June 1988 (λ=208°Ls) at ω=161°W, and in 2003 Parva Depressio was quite evident on Maurice VALIMBERTI’s image on 24 June 2003 (λ=209°Ls) at ω=127°W, and so we can suppose PICKERING was successful in detecting Parva Depressio on 22 May. On 31 May, they observed the surfaces showing Syrtis Mj and the rift was considered extending from 170°W to 345°W, and hence this was mainly occupied by Rima Australis including Parva Depressio. On 10 June DOUGLASS found another rift. The shadowy areas inside the spc play a serious and decisive role on LOWELL’s view of Mars and hence their start on 22 May can never be said too early. (We understand the day and time are described, if not specified, in terms of MST which is seven hrs west of GMT=GMST. GMST starts from the noon, and so the old day GMT=GMST is converted to the present day GMT by adding 12 hrs.)    


In 2005, the days correspond to the beginning of May 2005. On 10 May 2005, and λ=208°Ls with the angular diameter δ=7.1". If we want to pin down the spring equinox, we must start from around 24 March 2005. With respect to the happening of the 2001 dust storm, it is necessary to for us to be on a train of observations in March. Fortunately the sub-Earth point latitude on 1 March is 10°S, and henceforward the south pole declines further to us, and reaches about 25°S around the beginning of June. Next bottom will visit at the end of September to 10°S, but then rises up again.


We here digress, but we should like to stress that from the point of view of the dust circumstances which we encountered in 1973 (a sister apparition of 1894), it is also preferable to start earlier: It is known in 1973, at least two conspicuous dust disturbances occurred (biggest one was onset at λ=300°Ls), but there is a reason that there must have occurred another big dust disturbance much earlier which influenced the following dust storms. In 1973, Professor S MIYAMOTO started on 28 April 1973 (λ=195°Ls, δ7.1"), and we can consider that this was determined from the same background as employed by the Lowell team, but even then this was too late from the view-point of the dust phenomena.


Among many observations made by the Lowell team, LOWELL’s detection of two bright spots in the midst of the spc on 7 June is known as a pioneering work of the flare detection on the planet Mars. They dazzled like stars and flashed out and then disappeared after a few minutes. He calculated their position located at Ω=280°W~290°W, Φ=76°S and so it could be regarded to be associated with Novus Mons when it stayed still inside the spc. LOWELL knew that the detached Novus Mons had already been observed by MITCHEL in 1846 and GREEN in 1877, but this was observed around λ=218°Ls, and so totally inside. This was perhaps the reflection by the H2O ice. That Novus Mons is fully bright inside the spc was proved by the Viking mission. It may be attractive if there is a moment we can catch the sunlight reflection on the spc by an appropriate tilt of the axis.


As was pointed out also at the Conference last year, we may say DOUGLASS had a keen eye to the darker part, while LOWELL was inclined to detect bright spots. As noted, DOUGLASS checked another dark rift inside the spc on 10 June, while LOWELL found on 13 June a bright spot associated with the rift. In general, they were making a scrutiny along the terminator to detect brighter part or shadowy depression. 


During the campaign, it was reported they detected a total of 736 irregularities along the terminator, 694 out of which were measured. Of these 403 were depressions and 291 were the projections. We don’t here discuss about the unbalance of the numbers of the depressions and projections, nor their causes as atmospheric or geographical, but the concern about the terminator of the Lowell team look quite natural. Nowadays, the MOLA provides the geographical undulation in colour, but we feel somewhat frustration since MGS MOC images don’t provide the undulated limb but just flat limb (if not seen from the 14 hrs). In this sense the LOWELL description is quite attractive, and still these days the scrutiny along the critical terminator is necessary. Here we cite from the Mars book the observation of the terminator by W H PICKERING on 24 August 1894.


DOUGLASS made also an interesting observation on 26 and 27 November GMT of a bright spot which was detected in the unilluminated part of Mars. The one observed on 26 November at 4:35GMT was on the southern part of Protei Regio, and the one on 27 November appeared at 5:15 GMT nearly 9 degrees north. The description is quite detailed: if similar observation is made they are easily compared. They considered this to be an atmospheric variation. (Here the date and time have been converted into the modern GMT. If the time in the PICKERING limb observations is given in GMST, we should add 12 hrs to get GMT.)


Percival LOWELL was not a serious observer and often he was absent from Flagstaff even when the planet is in the very season, but we should say his plan of the 1894 campaign was quite successful maybe under the advisory PICKERING to cover the whole season of the southern hemisphere. As the spc thawed, Novus Mons was detached and they observed around from λ=238°Ls the deviation of the centre of the spc from the pole to the direction of ω=054°W, and decided the spc disappeared on 13 October. This was slightly before λ=300°Ls and should be said earlier than expected (at those time, it was believed the cap does not vanish as nowadays and soon grow large).


 The 1894 Mars was thus seen rather high in the sky from Flagstaff and we want to emphasise the 1894 Mars provided LOWELL to survey the possible cycle of the southern hemisphere to match his desire to be acquainted with the Martian season during the period from the season where the spc was largest to the season where the spc melted away. We also suggested their observations of the terminator should be revived in some sense.


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