Starship Asterisk*

Zodiacal Ray with Venus and Jupiter

Explanation: What's causing that unusual ray of light extending from the horizon? Dust orbiting the Sun. At certain times of the year, a band of sun-reflecting dust from the inner Solar System appears prominently after sunset or before sunrise and is called zodiacal light. The dust was emitted mostly from faint Jupiter-family comets and slowly spirals into the Sun. The featured HDR image, acquired in mid-February from the Sierra Nevada National Park in Spain, captures the glowing band of zodiacal light going right in front of the bright evening planets Jupiter (upper) and Venus (lower). Emitted from well behind the zodiacal light is a dark night sky that prominently includes the Pleiades star cluster. Jupiter and Venus are slowly switching places in the evening sky, and just in the next few days nearing their closest angular approach.

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Also visible: Mars (top), the Double Cluster (top right), Cassiopeia (top right), Pegasus (bottom right), and M31 (center right).

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.

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.

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.

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.

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?

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.

Amazing how the zodiac light; the planets; and the
seven sisters all lined up so neatly in the photo!