Starship Asterisk*

De58te wrote: ↑Thu May 21, 2020 10:49 am This picture reminds us just how ingrained we are about thinking that in astrophotography that North is at the top of the photo. Presuming that where Venus is lit up that the Sun would be above the picture, yet the description says that Venus will be 1/2 degree north of the Sun, so then it is South at the top of the photo and North is at the bottom. Am I wrong?

https://www.etymonline.com/search?q=phase wrote:
phase (n.) 1705, "phase of the moon, particular recurrent appearance presented by the moon (or Mercury or Venus) at a particular time," back-formed as a singular from Modern Latin phases, plural of phasis, from Greek phasis "appearance" (of a star), "phase" (of the moon), from stem of phainein "to show, to make appear".

Latin singular phasis was used in English from 1660 for each of the aspects of the moon. General (non-lunar) sense of "aspect, appearance, stage of development at a particular time" is attested by 1841. Meaning "temporary difficult period" (especially in reference to adolescents) is attested from 1913.

Sa Ji Tario wrote: ↑Thu May 21, 2020 1:42 pm In her book Astronomy, Cecilia Payne Gaposchkin says that the light reflected by Venus and captured on Earth always gives the same intensity value. Observe that as the planet gets closer to its visible area it is larger but its illuminated area drops, which causes the intensity of received light to always have the same value.-
Some of this has already been said by José Comas Solá when referring to the inner planets, in his book Astronomía (by chance of identical names, only that in Comas Solá's illustrations are drawings, therefore, older)

johnnydeep wrote: ↑Thu May 21, 2020 2:51 pm Hmm. I note that all these crescents are horizontal. Does that mean something particular about where the pictures were taken on the Earth? Is a horizontal crescent mandatory (or even possible) for an inferior planet when viewed from Earth? Or was this just depicted this way for artistic effect? Sorry if the answer should be obvious, but I always have trouble visualizing planetary geometry in 3D :-(

Chris Peterson wrote: ↑Thu May 21, 2020 3:03 pm

johnnydeep wrote: ↑Thu May 21, 2020 2:51 pm Hmm. I note that all these crescents are horizontal. Does that mean something particular about where the pictures were taken on the Earth? Is a horizontal crescent mandatory (or even possible) for an inferior planet when viewed from Earth? Or was this just depicted this way for artistic effect? Sorry if the answer should be obvious, but I always have trouble visualizing planetary geometry in 3D

The images have been aligned this way as an artistic choice. Venus has only a small axial tilt, so its crescent phases basically define north and south with respect to the ecliptic. The apparent angle we see it at (with respect to the horizon) depends on our latitude and where the planet is in the sky.

MarkBour wrote: ↑Thu May 21, 2020 5:19 pm

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That's a lovely composition and gives a very helpful comparison of the progression.

(And thanks to our APOD astronomers and curators for finding and sharing this.)

It might be fun to lay out these images on a depiction of the planetary orbits.

Something like the (very inaccurate) rendering at the right:

MarkBour wrote: ↑Thu May 21, 2020 5:19 pm That's a lovely composition and gives a very helpful comparison of the progression.
Thanks for that nice work, Richard Addis!
(And thanks to our APOD astronomers and curators for finding and sharing this.)

Capture.JPG

It might be fun to lay out these images on a depiction of the planetary orbits.

Something like the (very inaccurate) rendering at the right: