[AZ-Observing] Re: [sac-forum] FW: [ASKC] holmes size & data article

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Dick, the link below gives the message, "We're sorry, the SPACE.com page =
couldn't be found."  There is a long list of selections, but none seem =
to match the topic.  Is there another choice?

Clear skies,
aj

  ----- Original Message -----=20
  From: Richard Harshaw=20
  To: sac-forum@xxxxxxxxxxxxx ; az-observing@xxxxxxxxxxxxx=20
  Sent: Tuesday, November 20, 2007 8:23 AM
  Subject: [sac-forum] FW: [ASKC] holmes size & data article


  Good article and link on Holmes, =E2=80=9CThe Biggest Thing in the =
Solar System=E2=80=9D (right now, anyway).

  =20

  Dick H

  =20

  =20

  From: ASKC@xxxxxxxxxxxxxxx [mailto:ASKC@xxxxxxxxxxxxxxx]=20

  Sent: Tuesday, November 20, 2007 8:05 AM
  Subject: [ASKC] holmes size & data article

  =20

  article, links, and pics at:
  _http://www.space.com/spacewatch/071115-comet-holmes-size.html_=20
  (http://www.space.com/spacewatch/071115-comet-holmes-size.html)=20

  Incredible Comet Bigger than the Sun=20
  By Robert Roy Britt
  Senior Science Writer
  posted: 15 November 2007
  10:38 am ET

  A comet that has delighted backyard astronomers in recent weeks after =
an=20
  unexpected eruption has now grown larger than the sun.
  The sun remains by far the most massive object in the solar system, =
with an=20
  extended influence of particles that reaches all the planets. But the=20
  comparatively tiny Comet Holmes has released so much gas and dust that =
its extended=20
  atmosphere, or coma, is larger than the diameter of the sun. The =
comparison=20
  is clear in a new image.=20
  "It continues to expand and is now the largest single object in the =
solar=20
  system," according to astronomers at the University of Hawaii.=20
  The coma's diameter on Nov. 9 was 869,900 miles (1.4 million =
kilometers),=20
  based on measurements by Rachel Stevenson, Jan Kleyna and Pedro =
Lacerda of the=20
  University of Hawaii Institute for Astronomy. They used observations =
from the=20
  Canada-France-Hawaii Telescope. The sun's diameter, stated differently =
by=20
  various sources and usually rounded to the nearest 100, is about =
864,900 miles=20
  (1.392 million kilometers).
  Separately, a new Hubble Space Telescope photo of the comet reveals an =

  intriguing bow-tie structure around its nucleus.
  The comet's coma=E2=80=94mostly microscopic particles=E2=80=94shines =
by reflecting sunlight.
  See for yourself=20
  Holmes is still visible to the naked eye as a fuzzy star anytime after =
dark,=20
  high in the northeast sky. You can find it by using this sky map. It =
is=20
  faintly visible from cities, and from dark country locations is truly =
remarkable.=20
  "Right now, in a dark sky it appears as a very noticeable circular =
cloud,"=20
  said Joe Rao, SPACE.com's Skywatching Columnist. Rao advises looking =
for the=20
  comet this weekend, before the moon becomes more of a factor. The =
comet will=20
  likely diminish in brightness yet remain visible for the next two to =
three=20
  weeks, he said.=20
  "Over the next few weeks and months, the coma and tail are expected to =

  expand even more while the comet will fade as the dust disperses," =
Stevenson and=20
  her colleagues write.=20
  On Monday, Nov. 19, the comet will create a unique skywatching event =
with=20
  its see-through coma, according to the Web site Spaceweather.com: "The =
comet=20
  will glide by the star Mirfak [also called Alpha Persei] and appear to =
swallow=20
  it=E2=80=94a sight not to be missed."
  A small telescope will reveal the fuzzy coma. Lacking a long tail=20
  characteristic of some great comets, however, Holmes is not the most =
dramatic object in=20
  the sky for casual observers.
  Mystery outburst=20
  Nobody knows why Holmes erupted, but it underwent a similar explosive=20
  brightening in 1892. The recent display, which began Oct. 24, brought =
the comet=20
  from visual obscurity to being one of the brighter objects in the =
night sky. It=20
  has since dimmed somewhat as the material races outward from the =
nucleus at=20
  roughly 1,100 mph (0.5 km/sec).=20
  The Hawaiian astronomy team writes in a press statement: "This amazing =

  eruption of the comet is produced by dust ejected from a tiny solid =
nucleus made=20
  of ice and rock, only 3.6 kilometers (roughly 2.2 miles) in diameter."
  The new image from the Hawaiian observatory also shows a modest tail =
forming=20
  to one side, now just a fuzzy region to the lower-right. That's caused =
by=20
  the pressure of sunlight pushing on the gas and dust of the coma.=20
  But the comet is so far away=E2=80=94149 million miles (240 million =
kilometers), or=20
  about 1.6 times the distance from Earth to the sun=E2=80=94that even =
Hubble can't=20
  resolve its nucleus.
  The offset nature of the coma, seen in ground-based images, suggests =
"a=20
  large fragment broke off and subsequently disintegrated into tiny dust =
particles=20
  after moving away from the main nucleus," Hubble astronomers said in a =

  statement today. The comet's distance, plus all the dust, prevent =
Hubble from=20
  seeing any fragments, however.=20
  ...click the following for more ...
  The Greatest Comets of All Time=20
  Video: Comets Through Time ... Myths and Mystery=20
  Comet Image Gallery=20


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