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Mars at Its All-Time Finest

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  • blackstar7us
    Mars at Its All-Time Finest Page where the story of Mars started,with pictures at site: http://skyandtelescope.com/printable/observing/objects/planets/article
    Message 1 of 1 , Jul 2, 2003
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      Mars at Its All-Time Finest

      "Page where the story of Mars started,with pictures at site:
      http://skyandtelescope.com/printable/observing/objects/planets/article
      _988.asp

      SkyandTelescope.com
      Martian Flare Watch
      By Thomas A. Dobbins
      ----------------------------------------------------------------------
      "Story can be found at this address,with pictures at site:
      http://skyandtelescope.com/printable/observing/objects/planets/article
      _985.asp

      Tan Wei Leong of Singapore obtained this superb CCD image of Mars
      using an 11-inch telescope. Edom Promontorium, where numerous bright
      flares were seen in early June 2001, is near the central meridian in
      its normal non-flare state. South is up.




      Will Martian flares like those observed in 2001 appear again in 2003?
      Amateur and professional astronomers will be watching the red planet
      closely to find out.
      In the May 2001 issue of Sky & Telescope, my colleague William
      Sheehan and I discussed rare historical observations of bright, star-
      like flares from certain regions on the planet Mars. We suggested
      that the brightenings might be caused by specular (mirror-like)
      reflections of sunlight off water-ice crystals in surface frosts or
      thin clouds. Many of these glints were reported when the sub-Sun and
      sub-Earth points (where the Sun and Earth, respectively, are directly
      overhead as seen from Mars) were nearly coincident and close to the
      planet's central meridian, the imaginary line running down the center
      of the visible disk from pole to pole. Based on our analysis, we
      predicted that flares like those reported only four times between
      1894 and 1958 might erupt in the region known as Edom Promontorium,
      near the Martian equator at longitude 345°, in early June 2001.

      I organized an expedition to the Florida Keys, where the red planet
      would climb high in the south under exceptionally steady skies. Team
      members from Sky & Telescope and the Association of Lunar and
      Planetary Observers (ALPO) scrutinized the planet using a variety of
      telescopes nightly beginning June 5th. No flares were seen for the
      first two nights. But on June 7th, beginning around 06:35 Universal
      Time (2:35 a.m. Eastern Daylight Time), about 85 minutes before Edom
      crossed the central meridian, we saw a series of brightenings. Each
      lasted 3 to 5 seconds; they occurred once or twice a minute over the
      next hour and a half, until clouds ended the observations. The flares
      were seen visually at magnifications of 300x to 366x through two 6-
      inch (15-centimeter) Newtonian reflectors and were recorded on
      videotape at 1,400x through a Meade 12-inch (30-cm) Schmidt-
      Cassegrain telescope. Visually, the flares seemed to cut the dark
      linear feature Sinus Sabaeus nearly in two. More brightenings of Edom
      were observed on June 8th; these were as brilliant as the ones the
      night before but not as frequent. For details see IAU Circular 7642.


      One of several flares seen on June 7, 2001, peaks in brightness
      (left) and fades considerably less than a minute later (right). Both
      images are identically processed 9-frame composites from an SVHS
      video recording made through a 12-inch telescope. South is up.
      Courtesy David Moore.


      Our June 2001 observations support the idea that the flares came from
      sunlight glinting off patches of frost or ice on the Martian surface.
      Because the flashes occurred before Edom crossed the center of the
      planet's disk, the reflectors must have been tilted as much as 19°
      east-west; perhaps they rested on inclined surfaces on the ground,
      for example, the slopes of dunes. Intriguingly, the light-colored
      oval of Edom Promontorium corresponds to the large, flat crater
      Schiaparelli, and in May 2002 NASA's Mars Odyssey spacecraft found
      indications that this region is anomalously rich in water ice for a
      site near the Martian equator. The historical tendency of flares to
      occur when the sub-Sun and sub-Earth points are nearly coincident
      suggests to Masatsugu Minami, director of the Oriental Astronomy
      Association's Mars section, that the sources of the reflections lie
      at the bottoms of narrow fissures or trenches on the planet's
      surface.

      Mars observers and planetary scientists hope to learn more about the
      flare phenomenon during the red planet's 2003 apparition, now
      building toward a record-breaking closest approach in late August.
      Because Mars's southern hemisphere is tipped our way this year, the
      geometry precludes seeing any flares from Edom or other equatorial
      regions. Instead, specular reflections are likely from sites at more
      southerly Martian latitudes.

      In late July and early August this year, the sub-Sun and sub-Earth
      points will converge at a Martian latitude of –20°. By then the
      apparent diameter of Mars's gibbous disk will exceed 20 arc seconds.
      From July 24th through August 10th, observers should keep an eye on
      northern Thaumasia, northern Solis Lacus, southern Tithonius Lacus,
      Deucalonius Regio, Iapygia, and northern Hellas — all at or near
      latitude –20°. It will be interesting to see if specular reflections
      like those observed at Edom in 2001 are rare events that suggest
      something special about that site, or if they can be seen at many
      locations whenever the Mars-Sun-Earth geometry is favorable.

      Observations, both positive and negative, are welcomed by the Mars
      sections of both ALPO and the British Astronomical Association, as
      well as by the International Mars Watch. Of course, we also welcome
      your observing reports at Sky & Telescope!

      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      - - - - - - - - - - - - - - - - - - - - -

      Tom Dobbins is a contributing editor of Sky & Telescope magazine and
      the author of several acclaimed books on observing and imaging the
      solar system. S&T editors Rick Fienberg and Gary Seronik, who
      accompanied Dobbins to Florida in June 2001 and saw the Martian
      flares themselves, contributed to this article.
      ----------------------------------------------------------------------
      -

      Related Articles:

      Mars Odyssey Support for Visual Ice Flashes?
      A Mars Record for the Ages


      ©2003 Sky Publishing Corp.




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      "This web site can be found at this address,just text no pictures:
      http://cfa-www.harvard.edu/iauc/07600/07642.html#Item1



      Central Bureau for Astronomical Telegrams
      INTERNATIONAL ASTRONOMICAL UNION
      Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA
      02138, U.S.A.
      IAUSUBS@... or FAX 617-495-7231 (subscriptions)
      CBAT@... (science)
      URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
      Phone 617-495-7440/7244/7444 (for emergency use only)


      MARS
      R. Tresch Fienberg, Sky and Telescope (S&T), reports that he
      and a team of observers representing S&T and the Association of
      Lunar and Planetary Observers (T. Dobbins, G. Seronik, D. Parker,
      T. D'Auria, D. Moore, P. D'Auria, D. Troiani, S. Ireland, L.
      Ireland, C. Petersen, M. Petersen, and B. Itzenthaler), succeeded
      in detecting a brightening of Edom Promontorium during June 7 and
      8, both visually with two 0.15-m Newtonian reflectors and via
      monochrome videotape recorded with a 0.30-m Schmidt-Cassegrain
      reflector located in the Florida Keys, following predictions by
      Dobbins and Sheehan [2001, S&T 101(5), 115]. Observing conditions
      were good, with partly cloudy skies and excellent seeing. No
      brightenings were detected under good observing conditions on June
      5 and 6. A perceptible brightening of Edom was first detected
      around June 7.274 UT, about 85 min before the feature transited
      Mars' central meridian. By June 7.278, sporadic pulsations in
      brightness were evident, occurring once or twice a minute with
      brightness maxima of about 3-5 s duration that were not correlated
      with atmospheric turbulence; these brightness variations, which
      appeared along the north margin of Sinus Sabaeus, were seen
      simultaneously by visual observers and by those viewing the video
      monitor until June 7.312. Brightening around Edom also occurred
      on June 8, having intensity like that of June 7, with a series of
      short-lived (3- to 5-s) brightenings observed during June 8.292-
      8.306 and another series of frequent variations seen during June
      8.328-8.350. These specular reflections may continue for the next
      few nights, as detailed by Dobbins and Sheehan (op.cit.).



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