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Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Tue Dec 29, 2009 4:55 am
by APOD Robot
Rigel and the Witch Head Nebula
Explanation: Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe
Macbeth should have consulted the Witch Head Nebula. This suggestively shaped
reflection nebula on the lower left is associated with the
bright star Rigel, to its right, in the
constellation Orion. More formally known as
IC 2118, the Witch Head Nebula glows primarily by light reflected from
Rigel. Fine
dust in the nebula reflects the light.
Pictured above, the blue color of the Witch Head Nebula and of the dust surrounding
Rigel is caused not only by
Rigel's blue color but because the
dust grains reflect blue light more efficiently than red. The same
physical process causes
Earth's daytime sky to appear blue, although the scatterers in
Earth's atmosphere are molecules of
nitrogen and
oxygen. Rigel, the
Witch Head Nebula, and gas and dust that surrounds them lie about 800
light-years away.
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Tue Dec 29, 2009 2:22 pm
by neufer
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Tue Dec 29, 2009 3:31 pm
by geckzilla
Sorry neufer, your plans for using an image hosted by tripod are foiled today.
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Tue Dec 29, 2009 5:10 pm
by rigelan
Looks like its my turn to say, "Hey star, nice name!"
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Tue Dec 29, 2009 5:46 pm
by BMAONE23
At lease the Properties will allow you to drag out the HTTP address
http://pacek.tripod.com/WHSpage/man_in_the_moon1.gif
and see the image
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Tue Dec 29, 2009 6:38 pm
by Case
Or re-upload to a real image hosting service.
![Image](http://img690.imageshack.us/img690/264/maninthemoon1.gif)
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Tue Dec 29, 2009 6:52 pm
by neufer
Thanks to everyone for all the help.
Computer generated image of Rigel compared to the Sun (to scale)
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Wed Dec 30, 2009 1:40 am
by GaryR
neufer wrote:Thanks to everyone for all the help.
Computer generated image of Rigel compared to the Sun (to scale)
![Question :?:](./images/smilies/icon_question.gif)
How was the diameter of Rigel measured at 800 ly distance? Anyway, your computer-generated image makes the Sun look about the size of the Earth relative to the Sun! Also, how is the size of Rigel compared with that of Betelgeuse, a red supergiant?
GaryR
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Wed Dec 30, 2009 1:53 am
by geckzilla
Gary, if you scroll to the bottom of this page there is an illustration with Sol, Rigel, and Betelgeuse.
http://www.co-intelligence.org/newslett ... isons.html
Someone ought to do a better illustration. Somewhere along the line that one just got really poorly compressed. And actually I checked wikipedia and the relative sizes of the stars on that image seem to be wrong. Hmm.
I guess star radius guesses change a lot because there's a lot of contradictions even within Wikipedia. For instance, for
Deneb the caption to the picture says Deneb is 200-300 times the radius of the sun while the chart on the right claims it is 108-114 times the sun's radius.
Re: Rigel and the Witch Head Nebula (2009 Dec 29)
Posted: Wed Dec 30, 2009 5:06 am
by NoelC
An impressive image of that huge yet tenuous dust cloud.
I love how far amateur astrophotography has come.
-Noel