From Richard McKIM
@. . . . . . I was observing Mars earlier this
evening and Sinus Meridiani marked the eastern limit of the visible disk. No
dust obscuration was visible at about 22h UT (27 June). But we will chase the area
in the next few days.... even if by then nothing remains visible. The
description sounds typical of those
Yours Ever
(
@ . . . . . . . . . .Thank you for the images you
sent, from which it is clear that this dramatic event is similar to others from
the past. My research showed that regional events in Hellas could start as
early as Ls = 163ﾟ, and in
1986 and 1988 regional events there began around 180. The event imaged
resembles the 1988 June storm in that dust expanded eastward into Ausonia and
crossed Hesperia, but the interesting thing is that you remark there was a
cloud right from the start over part of M. Tyrrhenum (or perhaps Hesperia).
This may throw some light upon the origin of the large storm of 1894 which also
began in this region (affecting mostly M. Cimmerium) but whose initial cloud
was not caught.
If
the
I do recommend your
readers to get hold of a copy of my book about dust storms in which all these
past events are detailed. Copies can still be obtained through the BAA.
For the present event I will try to observe as
early as possible this evening to catch the storm's westward progress on the
eastern limb of the planet! Best wishes
(
@ . . . . . . . . . . .Thank you for your latest
email "Storm is now global". This seems just a little premature, for
I have not heard of there being any evidence that the longitudes of (for
instance) Mare Erythraeum or Solis Lacus have been affected, at least not up to
the time of writing this. The only thing global about the event is in terms of
coverage by observers!
Of course,
it may spread further, but if it did so it would be unusual for the current Ls.
One cannot compare this disturbance with the only truly global storm of 1971,
or even the encircling storms of the 20th century, from 1909 to the epoch of
Viking. It seems in this case that dust has propagated largely to the east,
invading the southern deserts including Hellas, Ausonia and Electris, and
obscuring Tyrrhenum M., Cimmerium M. and even the Syrtis Major and parts of the
N. hemisphere. In this respect the progression is reminiscent of aspects of the
regional storms of 1894 October, 1907 July, 1941 November, 1943 September, 1958
October, etc...., though only the 1907 event was at a reasonably similar Ls. In
some of these cases dust stretched three-quarters of the way around Mars, but
one would not describe any of them as being global or even encircling.
Historically, the great encircling events have only broken out later in the
season, and seem to require a secondary, independent focus of activity to
develop to enable them to reach encircling status. Thus the seasonally earliest
encircling event commenced at Ls = 204ﾟ.
There have been many other
I was
observing last night (July 1 U.T., with my 42-cm Dall-Kirkham Cassegrain) under
CM = 325-335ﾟW and
found a general loss of contrast, but the markings all clearly recognisable.
The Syrtis Major was clearly visible though a little pale, except at the N.
end. The Mare Serpentis area was well marked. Libya-Isidis and
With sincere good wishes,
(
@ . . . . . . . . .Just a note to thank everyone for
their work this apparition, and to ask anyone with images or drawings to send
to let me have them. I am away from home from tomorrow till July 28, so will be
unable to read or answer email from now until then. Some of you may wish to
keep images and send them after my return, but send them in as you get them if
you wish. For interest I attach a draft summary of the apparition and
personnel, as submitted to the BAA Council for publication in the October
number of the Journal. It is intended to update the Section's web page in due
course. With best wishes
(
Richard McKIM (Peterborough,
UK)
BAA Mars Secrion Director