Starship Asterisk*

Ann wrote:Congratulations, Sara! I don't remember the last time a woman's image was made the Astronomy Picture of the Day.

Yours is very well-deserved. All the dusty features in and near the Cygnus Wall are very intriguing.

Ann

Fred the Cat wrote:I always wonder, "What would that nebula look like if you could see it in 3D?"

MarkBour wrote:

Fred the Cat wrote:I always wonder, "What would that nebula look like if you could see it in 3D?" 8-)

That is fantastic. Actually, if they have all that data, they could make it interactive like the recent APOD image of C67P. I'd like that even better.

MarkBour wrote:How opaque are the clouds? I would guess that they are more or less completely opaque.

Chris Peterson wrote:

MarkBour wrote:
How opaque are the clouds? I would guess that they are more or less completely opaque.

You need to define what you mean by "opaque" when asking that kind of question. The densest parts of the clouds are still a hard vacuum. Much more tenuous than Earth's atmosphere, for instance. And our atmosphere is more opaque by orders of magnitude than this nebula.

https://en.wikipedia.org/wiki/Dark_nebula wrote:

[b][color=#0000FF][size=200]The Horsehead Nebula[/size][/color][/b]

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<<A dark nebula or absorption nebula is a type of interstellar cloud that is so dense it obscures the light from objects behind it, such as background stars and emission or reflection nebulae. The extinction of the light is caused by interstellar dust grains located in the coldest, densest parts of larger molecular clouds. Clusters and large complexes of dark nebulae are associated with Giant Molecular Clouds. In the inner outer molecular regions of dark nebulae, important events take place, such as the formation of stars and masers.

Dark clouds appear so because of sub-micrometre-sized dust particles, coated with frozen carbon monoxide and nitrogen, which effectively block the passage of light at visible wavelengths. Also present are molecular hydrogen, atomic helium, C¹⁸O (CO with oxygen as the ¹⁸O isotope), CS, NH₃ (ammonia), H₂CO (formaldehyde), c-C₃H₂ (cyclopropenylidene) and a molecular ion N₂H⁺ (diazenylium), all of which are relatively transparent. These clouds are the spawning grounds of stars and planets, and understanding their development is essential to understanding star formation.

The form of such dark clouds is very irregular: they have no clearly defined outer boundaries and sometimes take on convoluted serpentine shapes. The largest dark nebulae are visible to the naked eye, appearing as dark patches against the brighter background of the Milky Way like the Coalsack Nebula and the Great rift. These naked-eye objects are sometimes known as dark cloud constellations and take on a variety of names.>>

Chris Peterson wrote:

MarkBour wrote:How opaque are the clouds? I would guess that they are more or less completely opaque.

You need to define what you mean by "opaque" when asking that kind of question. The densest parts of the clouds are still a hard vacuum. Much more tenuous than Earth's atmosphere, for instance. And our atmosphere is more opaque by orders of magnitude than this nebula.