Chris Peterson wrote:When you look at these dust clouds in the Milky Way, or dust lanes in other galaxies, you are seeing structures on a scale of kiloparsecs.
Typical visible-band extinction values in these dust clouds are on the order of a few magnitudes/kpc.
In terms of astronomical units, you are looking at nanomagnitudes. In other words, if our solar system were in the midst of a galactic dust lane, we'd see a drop in solar radiation on the order of microwatts per square meter (on the normal value of around 1 kw/m^2). I don't think our current technology is good enough to even detect such a small change. The reduction in energy we'd receive from the Sun if we were in a dust cloud is smaller than the reduction caused by a single small sunspot.
Indeed, I wouldn't be surprised if the dust density within the Solar System right now is much greater than the dust density in galactic clouds.
http://en.wikipedia.org/wiki/Zodiacal_light wrote:
<<The zodiacal light is produced by sunlight reflecting off dust particles in the solar system known as cosmic dust. Consequently, its spectrum is the same as the solar spectrum. The material producing the zodiacal light is located in a lens-shaped volume of space centered on the sun and extending well out beyond the orbit of Earth. This material is known as the interplanetary dust cloud. Since most of the material is located near the plane of the solar system, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is amazingly small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth's moon, each particle would be 8 km from its neighbors. The gegenschein may be because particles directly opposite the sun as seen from Earth would be in full phase.
1 optical depth of zodiacal dust ~ [(8 × 10^6)^3 mm]/ (30.857 × 10^18 mm/parsec)
1 optical depth of zodiacal dust ~ 16.6 parsecs.
60 optical depths of zodiacal dust ~ 1 kiloparsec
Zodiacal dust visible-band extinction ~ 65 magnitudes / kpc
http://www.andrewcollins.com/page/articles/thecygnusmystery_well.htm wrote:
<<Ancient Egyptian cosmology talks about a bird known as the Great Cackler, a cosmic goose, who brings the universe into manifestation by letting out a divine honk or call. It lays the sun-egg from which the creator god emerges, his name altering depending on which cult centre the myth is attached. On the famous round zodiac of Denderah, created as late as c. 50 BC, there appears a cosmic goose, and careful analysis of its position in the night sky shows that it formed part of a constellation composed of the stars of Cygnus and the bright star Altair in Aquila, the celestial eagle, an area of the Milky Way dominated by the dark nebulous region known as
the Great Rift. This indicates that the Ancient Egyptians saw the point of creation as located in the vicinity of Cygnus. In addition to this, the Great Cackler was a totem of Geb, the earth god, whose wife/lover was Nut, the sky-goddess. Occasionally, the Great Cackler is shown at the feet of Nut as she is prised apart from Geb in order to form the sky and earth.>>
[quote="Chris Peterson"]When you look at these dust clouds in the Milky Way, or dust lanes in other galaxies, you are seeing structures on a scale of kiloparsecs.
[b]Typical visible-band extinction values in these dust clouds are on the order of a few magnitudes/kpc.[/b]
In terms of astronomical units, you are looking at nanomagnitudes. In other words, if our solar system were in the midst of a galactic dust lane, we'd see a drop in solar radiation on the order of microwatts per square meter (on the normal value of around 1 kw/m^2). I don't think our current technology is good enough to even detect such a small change. The reduction in energy we'd receive from the Sun if we were in a dust cloud is smaller than the reduction caused by a single small sunspot.
Indeed,[b] I wouldn't be surprised if the dust density within the Solar System right now is much greater than the dust density in galactic clouds.[/b][/quote]
[quote=" http://en.wikipedia.org/wiki/Zodiacal_light"]
<<The zodiacal light is produced by sunlight reflecting off dust particles in the solar system known as cosmic dust. Consequently, its spectrum is the same as the solar spectrum. The material producing the zodiacal light is located in a lens-shaped volume of space centered on the sun and extending well out beyond the orbit of Earth. This material is known as the interplanetary dust cloud. Since most of the material is located near the plane of the solar system, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is amazingly small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth's moon, each particle would be 8 km from its neighbors. The gegenschein may be because particles directly opposite the sun as seen from Earth would be in full phase.
1 optical depth of zodiacal dust ~ [(8 × 10^6)^3 mm]/ (30.857 × 10^18 mm/parsec)
1 optical depth of zodiacal dust ~ 16.6 parsecs.
60 optical depths of zodiacal dust ~ 1 kiloparsec
[b]Zodiacal dust visible-band extinction ~ 65 magnitudes / kpc[/b][/quote]
[quote=" http://www.andrewcollins.com/page/articles/thecygnusmystery_well.htm"]
<<Ancient Egyptian cosmology talks about a bird known as the Great Cackler, a cosmic goose, who brings the universe into manifestation by letting out a divine honk or call. It lays the sun-egg from which the creator god emerges, his name altering depending on which cult centre the myth is attached. On the famous round zodiac of Denderah, created as late as c. 50 BC, there appears a cosmic goose, and careful analysis of its position in the night sky shows that it formed part of a constellation composed of the stars of Cygnus and the bright star Altair in Aquila, the celestial eagle, an area of the Milky Way dominated by the dark nebulous region known as [url=http://apod.nasa.gov/apod/ap960515.html][b]the Great Rift[/b][/url]. This indicates that the Ancient Egyptians saw the point of creation as located in the vicinity of Cygnus. In addition to this, the Great Cackler was a totem of Geb, the earth god, whose wife/lover was Nut, the sky-goddess. Occasionally, the Great Cackler is shown at the feet of Nut as she is prised apart from Geb in order to form the sky and earth.>>[/quote]