Starship Asterisk*

neufer wrote: ↑Fri Feb 04, 2022 2:29 am

johnnydeep wrote: ↑Thu Feb 03, 2022 9:40 pm

Roger Venable wrote: ↑Thu Feb 03, 2022 12:24 pm
In these two images, though both Venus and the Moon are nominally illuminated in the same percentage of their Earth-facing hemispheres, the cusps of Venus appear to extend further toward the north and south extremes than those of Luna do. This is not an illusion. Venus has an upper layer of thin clouds that exhibit forward scattering, making the cusps appear brighter than would be expected with the illumination of a smooth sphere. In contrast, Luna's rough surface does not scatter forward, and actually partially shadows the terminator, making the cusps appear darker than would be expected with the illumination of a smooth sphere. This effect is even more pronounced with crescents of the two bodies are thinner than those presented in these images. Sometimes when very close to inferior conjunction a faint but complete ring of light can be seen around Venus, while near new moon each month the visible part of the lunar crescent appears very diminished, often to less than 90 degrees of the lunar circumference.

I think I follow your reasoning here,

but I honestly don't seen any difference in the extent of the Moon's and Venus' cusps in this APOD.

https://en.wikipedia.org/wiki/Venus#Ashen_light wrote:
<<A long-standing mystery of Venus observations is the so-called ashen light—an apparent weak illumination of its dark side, seen when the planet is in the crescent phase. The first claimed observation of ashen light was made in 1643, but the existence of the illumination has never been reliably confirmed. Observers have speculated it may result from electrical activity in the Venusian atmosphere, but it could be illusory, resulting from the physiological effect of observing a bright, crescent-shaped object.>>

johnnydeep wrote: ↑Thu Feb 03, 2022 9:40 pm

Roger Venable wrote: ↑Thu Feb 03, 2022 12:24 pm
In these two images, though both Venus and the Moon are nominally illuminated in the same percentage of their Earth-facing hemispheres, the cusps of Venus appear to extend further toward the north and south extremes than those of Luna do. This is not an illusion. Venus has an upper layer of thin clouds that exhibit forward scattering, making the cusps appear brighter than would be expected with the illumination of a smooth sphere. In contrast, Luna's rough surface does not scatter forward, and actually partially shadows the terminator, making the cusps appear darker than would be expected with the illumination of a smooth sphere. This effect is even more pronounced with crescents of the two bodies are thinner than those presented in these images. Sometimes when very close to inferior conjunction a faint but complete ring of light can be seen around Venus, while near new moon each month the visible part of the lunar crescent appears very diminished, often to less than 90 degrees of the lunar circumference.

I think I follow your reasoning here,

but I honestly don't seen any difference in the extent of the Moon's and Venus' cusps in this APOD.

https://en.wikipedia.org/wiki/Venus#Ashen_light wrote:
<<A long-standing mystery of Venus observations is the so-called ashen light—an apparent weak illumination of its dark side, seen when the planet is in the crescent phase. The first claimed observation of ashen light was made in 1643, but the existence of the illumination has never been reliably confirmed. Observers have speculated it may result from electrical activity in the Venusian atmosphere, but it could be illusory, resulting from the physiological effect of observing a bright, crescent-shaped object.>>

Roger Venable wrote: ↑Thu Feb 03, 2022 12:24 pm In these two images, though both Venus and the Moon are nominally illuminated in the same percentage of their Earth-facing hemispheres, the cusps of Venus appear to extend further toward the north and south extremes than those of Luna do. This is not an illusion. Venus has an upper layer of thin clouds that exhibit forward scattering, making the cusps appear brighter than would be expected with the illumination of a smooth sphere. In contrast, Luna's rough surface does not scatter forward, and actually partially shadows the terminator, making the cusps appear darker than would be expected with the illumination of a smooth sphere. This effect is even more pronounced with crescents of the two bodies are thinner than those presented in these images. Sometimes when very close to inferior conjunction a faint but complete ring of light can be seen around Venus, while near new moon each month the visible part of the lunar crescent appears very diminished, often to less than 90 degrees of the lunar circumference.