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Lunar eclipse tonight, perfect caching weather

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  • Teeje
    Subject: Lunar eclipse tonight http://skyandtelescope.com/observing/objects/eclipses/article_1340_1.asp October s Ideal Lunar Eclipse By Alan M. MacRobert
    Message 1 of 1 , Oct 27, 2004
      Subject: Lunar eclipse tonight


      October's Ideal Lunar Eclipse
      By Alan M. MacRobert

      Total lunar eclipse
      This view of totality, taken on January 9, 2001, by Swedish
      astrophotographer Bengt Ask, shows the eclipsed Moon amid several
      bright stars in Gemini. He used an 8-inch Schmidt-Cassegrain reflector
      with a focal reducer and a 6-second exposure on ISO 400 film to
      capture this scene. Totality on October 27–28, 2004, may look like
      this, as the geometries of the 2001 and 2004 eclipses are similar.

      The best astronomical events usually seem to happen at the worst times
      and places at 3 a.m. low above your most obstructed horizon, or maybe
      only in East Antarctica. But not this time, not for observers anywhere
      in the Americas. On October 27, 2004, the full Moon will undergo a
      deep total eclipse lasting for 1 hour 22 minutes, when it will be high
      in the eastern sky after dark but while most people are still awake
      and about.

      The only slightly problematic area will be near the West Coast of
      North America, where the partial phase of the eclipse will begin just
      a few minutes after sunset and moonrise. But if you have an open view
      low to the east, even this situation will only add to the drama. As
      twilight fades, westerners will see the shadow-bitten Moon coming into
      stark view low above the landscape, and by the time totality begins,
      the sky will be getting quite dark and the Moon will be fairly high.

      What's more, in a conjunction of events never before seen in history,
      this eclipse happens during Game 4 of the World Series. The World
      Series Lunar Eclipse should be visible to fans with good sight lines
      from Busch Memorial Stadium in St. Louis, and we can hope that TV
      crews periodically aim up to show the progress of the event — if the
      sky is not too cloudy!
      Millions of watchers could be inspired to duck outside for a look
      between innings. (P.S.: Go Sox!)

      Europe and much of Africa also get a good view of the eclipse, but at
      a less convenient time: before dawn on the morning of October 28th.

      Regions of eclipse visiblilty

      Find your location to see whether the Moon will rise or set during any
      phase of the eclipse for you. Because an eclipsed Moon is always full,
      the Sun sets or rises almost simultaneously on the opposite horizon. Sky &
      Telescope: Gregg Dinderman.

      If you're clouded out (or can't see the eclipse from your location), try
      these sites for possible live webcasts of the eclipse:

      * MIRA Public Observatory, Belgium
      * Saro Group Scientific Expeditions, Canary Islands
      * High Moon, Switzerland
      * Universidad de Sonora, Mexico
      * ParsSky.net, Iran
      * AstroNet, Netherlands
      * East Antrim Astronomical Society, Northern Ireland
      * Friends of Astronomy, Argentina

      The Sequence of Events

      Path of Moon through Earth's shadow

      During this eclipse, the Moon (in Aries) crosses deep inside the northern
      part of Earth's shadow core (the umbra). The partial phases before and
      after totality occur while the Moon is moving across the umbra's edge.
      Much less noticeable are the stages when the Moon is in the shadow's pale
      penumbra. The diagram gives Universal Times on October 28th. The table at
      the bottom of the page lists the corresponding Eastern, Central,
      and Pacific Daylight Times on the evening of the 27th and morning of the
      28th. Sky & Telescope: Gregg Dinderman.

      The illustration at right shows the Universal Times of events as the Moon
      moves into and out of the two parts of Earth's shadow: the penumbra, the
      shadow's pale outer fringe, and the umbra, the darker central region. The
      table below gives the civil times of events in North American time zones.

      The outermost part of the penumbra is so lightly shaded that you won't
      notice any change on the Moon here at all. But by the time the Moon's
      leading edge gets about halfway across the penumbra, you may begin to
      detect a very weak dimming of the Moon's eastern side. How early can you
      be certain you see it? As the Moon advances farther across the penumbra,
      the shading becomes much stronger and more obvious.

      When the Moon's edge first reaches the umbra, true partial eclipse
      The change is dramatic. A dark dent forms in the Moon's eastern side, and
      as the minutes tick by, the dent becomes a big, curved bite. In a
      telescope you can watch the umbra's slightly ill-defined edge engulf one
      familiar lunar feature after another.

      After 1 hour 9 minutes of partial eclipse, the last edge of the Moon
      out of partial sunlight into the umbra. But already it has become
      that the umbra is not completely dark. The shaded area of the Moon glows
      with a weird reddish hue anywhere from bright sunset-orange to dark
      blood-black. This illumination on the Moon is sunlight that is bent by
      atmosphere around the edge of Earth into the planet's shadow. The strange
      light on a totally eclipsed Moon is the combined illumination from all
      sunrises and sunsets ringing the Earth at the time.

      The actual brightness of the Earth's sunrise-sunset ring depends on
      weather conditions around the world and especially on the amount of dust
      suspended in the upper atmosphere. A clear stratosphere on Earth
      produces a bright and colorful lunar eclipse, with coppery and orange
      colors predominating. A major volcanic eruption can load the stratosphere
      with a thin haze of ash and dust, resulting in very dark lunar eclipses
      such as occurred for several years after the enormous eruptions of Mount
      Pinatubo in the Philippines in 1991, Mexico's El Chichón in 1982, and
      Indonesia's Mount Agung in 1963. Recent lunar eclipses have been much
      lighter, and this one should be too.

      Even during a given eclipse, colors and shades in the umbra can be
      surprisingly varied. The Moon will pass north of the shadow's center this
      time, so around mideclipse time the north (upper) part of the Moon will
      almost certainly look brighter than its bottom part because that region
      will be closest to the umbra's edge. Time-lapse photography sometimes
      reveals mysterious bands of darker shadow sweeping across the Moon during
      totality. Around the beginning and end of total eclipse, you'll probably
      see a bright yellowish or even bluish white arc just inside the umbra's
      edge. These effects can give the eclipsed Moon a remarkably
      three-dimensional appearance, making it look like a luminous rotten

      After totality, the partial phases unwind in reverse order as the Moon
      creeps out of the umbra. But even when the last edge of the Moon leaves
      the umbra, the show is not over. The penumbral shading should remain
      visible on the Moon's celestial west (right) side for another 30 minutes
      or so. When will you lose the last definite trace of it?

      Total Eclipse of the Moon, October 27–28, 2004
      Eclipse stage UT Eastern Daylight Time Central Daylight Time
      Mountain Daylight Time Pacific Daylight Time
      Moon enters penumbra 0:05 8:05 p.m. 7:05 p.m. 6:05
      p.m. --
      First visible shading? 0:45 8:45 p.m. 7:45 p.m. 6:45
      p.m. --
      Partial eclipse begins 1:14 9:14 p.m. 8:14 p.m. 7:14
      p.m. --
      Total eclipse begins 2:23 10:23 p.m. 9:23 p.m. 8:23
      p.m. 7:23 p.m.
      Total eclipse ends 3:45 11:45 p.m. 10:45 p.m. 9:45
      p.m. 8:45 p.m.
      Partial eclipse ends 4:54 12:54 a.m. 11:54 p.m. 10:54 p.m.
      9:54 p.m.
      Last visible shading? 5:25 1:25 a.m. 12:25 a.m. 11:25 p.m.
      10:25 p.m.
      Moon leaves penumbra 6:03 2:03 a.m. 1:03 a.m. 12:03 a.m.
      11:03 p.m.

      Estimating Brightness

      Lunar eclipse sequence
      Aligning his camera on the same star for nine successive exposures, Sky &
      Telescope contributing photographer Akira Fujii captured this record of
      the Moon's progress dead center through the Earth's shadow during the
      2000 total lunar eclipse.

      About a century ago, the French astronomer André Danjon devised a scale
      for rating the overall darkness of lunar eclipses. Estimates of the
      "Danjon number" form another long-running record of lunar-eclipse
      variations, so they are well worth continuing again, partly to calibrate
      what the number may say about atmospheric conditions before modern types
      of measurements. Here are Danjon's L (for luminosity) values:

      Danjon Scale of Brightness
      L Value Description
      0 Very dark eclipse, Moon almost invisible,
      especially at midtotality.
      1 Dark eclipse, gray or brownish coloration;
      details distinguishable only with difficulty.
      2 Deep red or rust-colored eclipse, with a
      very dark central part in the umbra and
      the outer rim of the umbra relatively bright.
      3 Brick-red eclipse, usually with a bright
      or yellow rim to the umbra.
      4 Very bright copper-red or orange eclipse,
      with a bluish, very bright umbral rim.

      A fractional estimate, such as 1.8 or 3.2, may seem most appropriate.

      A more objective method is to estimate the actual stellar magnitude of
      eclipsed Moon, using the "reversed binocular" trick. This was recently
      perfected by Brazilian observers Helio C. Vital, Alexandre Amorim,
      Souza, and Antonio R. Campos. During the total lunar eclipse of May
      2003, for instance, they found that the Moon seen through one barrel of
      backward-turned binoculars matched the brightness of the star Pi Scorpii
      (magnitude +2.9) seen in the open sky. Prior tests had established that
      the binoculars produced 5.0 magnitudes of dimming. This meant that the
      eclipsed Moon was magnitude 2.1.

      Please e-mail any of these observations you make to
      rsinnott@... giving your full name and address, the
      telescope aperture and magnification, and the sky conditions.

      Eclipse Photography

      Total lunar eclipse from beginning to end
      This interesting chronicle of totality on November 8, 2003, was made by
      Joe Pedit from Cusco Willa, Virginia. He used a stationary Nikon N90s SLR
      camera with a 24-mm lens at f/22 and Kodak Professional Supra 400
      color-negative film for this exposure lasting 3 hours 21 minutes. The
      intense brightness of the full Moon overexposed the beginning and end of
      the trail.

      Unlike a total eclipse of the Sun, which usually lasts for only a few
      frenzied minutes, a total lunar eclipse happens at a much more leisurely
      pace. For example, on October 27th the Moon will be completely
      immersed in
      Earth's shadow core, or umbra, for 1 hour 22 minutes. This makes it a
      treat both to watch and to image, using either still or time-lapse
      photography — especially if you have a long lens or can shoot through a
      telescope. See either "How to Capture October's Lunar Eclipse" in the
      October 2004 issue of Sky & Telescope magazine, or the online article
      "Observing and Photographing Lunar Eclipses" for guidelines on shooting a
      lunar eclipse.

      Just hope for clear weather! The world has had a run of four total lunar
      eclipses (counting this one) in just the last year and a half, but there
      won't be another one visible from anywhere until March 3rd and August 28th
      of 2007. Europe and the East Coast of North America are favored for the
      first of these, western North America for the second.

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      Sky & Telescope senior editor Alan MacRobert made his first crater
      during the eclipse of April 13, 1968.


      Peace: It's not just a good idea, it's a way of life!
      Don't push away the darkness, turn toward and embrace the light.
      Why *not* go out on a limb? That's where the fruit is! -- Mark Twain
      Always bear in mind that your own resolution to succeed
      is more important than any other one thing. -- Abraham Lincoln
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