Comments and questions about the
APOD on the main view screen.
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dcrooks1960
- Asternaut
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- Joined: Sat Feb 25, 2023 4:47 pm
Post
by dcrooks1960 » Mon Feb 27, 2023 2:20 pm
Also visible: Mars (top), the Double Cluster (top right), Cassiopeia (top right), Pegasus (bottom right), and M31 (center right).
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Fred the Cat
- Theoretic Apothekitty
- Posts: 975
- Joined: Mon Feb 22, 2016 4:09 pm
- AKA: Ron
- Location: Eagle, Idaho
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by Fred the Cat » Mon Feb 27, 2023 6:01 pm
How long of a trip would a spacecraft have to travel north from the
galactic plane in order to see the Milky Way from a high enough angle to reveal its structure?
By the time we go
48,000 light-years at our current
highest speed to clearly see our
galaxy, we’d probably already have a pretty good map. Too bad we can’t live for
cosmic years.
![Neutral :|](./images/smilies/icon_neutral.gif)
Freddy's Felicity "Only ascertain as a cat box survivor"
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johnnydeep
- Commodore
- Posts: 3079
- Joined: Sun Feb 20, 2011 8:57 pm
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by johnnydeep » Mon Feb 27, 2023 7:27 pm
Fred the Cat wrote: ↑Mon Feb 27, 2023 6:01 pm
How long of a trip would a spacecraft have to travel north from the
galactic plane in order to see the Milky Way from a high enough angle to reveal its structure?
By the time we go
48,000 light-years at our current
highest speed to clearly see our
galaxy, we’d probably already have a pretty good map.
Too bad we can’t live for cosmic years.
Indeed. The entire universe is only about 13.5 * 4 = 54 "milky way years" old! (given that the M-W takes about 250 My to rotate back to the same position relative to the distant background galaxies.
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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johnnydeep
- Commodore
- Posts: 3079
- Joined: Sun Feb 20, 2011 8:57 pm
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by johnnydeep » Mon Feb 27, 2023 7:32 pm
So, can we say here whether Venus is behind, embedded, or in from of this zodiacal dust? I take it that Jupiter is well behind it. From:
https://en.wikipedia.org/wiki/Zodiacal_light wrote: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 quite 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.
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"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Chris Peterson
- Abominable Snowman
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- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
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Contact:
Post
by Chris Peterson » Mon Feb 27, 2023 8:13 pm
johnnydeep wrote: ↑Mon Feb 27, 2023 7:32 pm
So, can we say here whether Venus is behind, embedded, or in from of this zodiacal dust? I take it that Jupiter is well behind it. From:
https://en.wikipedia.org/wiki/Zodiacal_light wrote: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 quite 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.
Venus is on the other side of the Sun from us. That is, if you were to travel from the Earth to Venus, you'd get closer to the Sun for about half the trip, and then be getting farther from the Sun. So the light path follows a complicated dust density profile.
That said, while zodiacal light forms a complete band across the sky, forward scattering is much stronger than back scattering. So pretty much all of the light we're seeing here is from dust between us and the Sun, not dust behind it. Which means Venus is behind the zodiacal light.
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johnnydeep
- Commodore
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Post
by johnnydeep » Mon Feb 27, 2023 8:37 pm
Chris Peterson wrote: ↑Mon Feb 27, 2023 8:13 pm
johnnydeep wrote: ↑Mon Feb 27, 2023 7:32 pm
So, can we say here whether Venus is behind, embedded, or in from of this zodiacal dust? I take it that Jupiter is well behind it. From:
https://en.wikipedia.org/wiki/Zodiacal_light wrote: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 quite 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.
Venus is on the other side of the Sun from us. That is, if you were to travel from the Earth to Venus, you'd get closer to the Sun for about half the trip, and then be getting farther from the Sun. So the light path follows a complicated dust density profile.
That said, while zodiacal light forms a complete band across the sky, forward scattering is much stronger than back scattering. So pretty much all of the light we're seeing here is from dust between us and the Sun, not dust behind it. Which means Venus is behind the zodiacal light.
Thanks. So Venus is behind (most of) the dust that's producing the zodiacal light we see here, but Venus is still quite embedded in the overall zodiacal dust lenticular disk, right?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Chris Peterson
- Abominable Snowman
- Posts: 18459
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
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Contact:
Post
by Chris Peterson » Tue Feb 28, 2023 12:05 am
johnnydeep wrote: ↑Mon Feb 27, 2023 8:37 pm
Chris Peterson wrote: ↑Mon Feb 27, 2023 8:13 pm
johnnydeep wrote: ↑Mon Feb 27, 2023 7:32 pm
So, can we say here whether Venus is behind, embedded, or in from of this zodiacal dust? I take it that Jupiter is well behind it. From:
Venus is on the other side of the Sun from us. That is, if you were to travel from the Earth to Venus, you'd get closer to the Sun for about half the trip, and then be getting farther from the Sun. So the light path follows a complicated dust density profile.
That said, while zodiacal light forms a complete band across the sky, forward scattering is much stronger than back scattering. So pretty much all of the light we're seeing here is from dust between us and the Sun, not dust behind it. Which means Venus is behind the zodiacal light.
Thanks. So Venus is behind (most of) the dust that's producing the zodiacal light we see here, but Venus is still quite embedded in the overall zodiacal dust lenticular disk, right?
Yeah. It's not behind most of the dust, just behind the dust that we're seeing.
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orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
Post
by orin stepanek » Tue Feb 28, 2023 3:47 am
Amazing how the zodiac light; the planets; and the
seven sisters all lined up so neatly in the photo!
![Cool 8-)](./images/smilies/icon_cool.gif)
Orin
Smile today; tomorrow's another day!