“Nadir” and “zenith” in Alliance-Union universe space navigation
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In C.J. Cherryh's Chanur novels (part of her Alliance-Union universe) there's sometimes talk of starships arriving in a solar system at the system's nadir or zenith. At first I thought this just meant being outside of the system's planetary ecliptic, with nadir and zenith meaning the star's "north" and "south". However, further in there's discussion about the sorts of things a starship can pull off are different depending upon if they enter nadir or zenith, which doesn't make sense if those words just indicate in which direction a starship has deviated from the ecliptic.
So what exactly do the terms mean in the context of the Chanur novels?
spaceship terminology alliance-union
edited 52 mins ago
DavidW
4,06911452
asked Sep 3 '17 at 3:03
Matthew ClineMatthew Cline
1855
add a comment |
In C.J. Cherryh's Chanur novels (part of her Alliance-Union universe) there's sometimes talk of starships arriving in a solar system at the system's nadir or zenith. At first I thought this just meant being outside of the system's planetary ecliptic, with nadir and zenith meaning the star's "north" and "south". However, further in there's discussion about the sorts of things a starship can pull off are different depending upon if they enter nadir or zenith, which doesn't make sense if those words just indicate in which direction a starship has deviated from the ecliptic.
So what exactly do the terms mean in the context of the Chanur novels?
spaceship terminology alliance-union
edited 52 mins ago
DavidW
4,06911452
asked Sep 3 '17 at 3:03
Matthew ClineMatthew Cline
1855
These terms are not a sci-fi specific. They show up in astronomy and aerial navigation as well. You should move this question to another SE forum.
– RichS
Sep 3 '17 at 3:37
This question would be more appropriate in the astronomy forum.
– RichS
Sep 3 '17 at 3:53
add a comment |
In C.J. Cherryh's Chanur novels (part of her Alliance-Union universe) there's sometimes talk of starships arriving in a solar system at the system's nadir or zenith. At first I thought this just meant being outside of the system's planetary ecliptic, with nadir and zenith meaning the star's "north" and "south". However, further in there's discussion about the sorts of things a starship can pull off are different depending upon if they enter nadir or zenith, which doesn't make sense if those words just indicate in which direction a starship has deviated from the ecliptic.
So what exactly do the terms mean in the context of the Chanur novels?
spaceship terminology alliance-union
edited 52 mins ago
DavidW
4,06911452
asked Sep 3 '17 at 3:03
Matthew ClineMatthew Cline
1855
In C.J. Cherryh's Chanur novels (part of her Alliance-Union universe) there's sometimes talk of starships arriving in a solar system at the system's nadir or zenith. At first I thought this just meant being outside of the system's planetary ecliptic, with nadir and zenith meaning the star's "north" and "south". However, further in there's discussion about the sorts of things a starship can pull off are different depending upon if they enter nadir or zenith, which doesn't make sense if those words just indicate in which direction a starship has deviated from the ecliptic.
So what exactly do the terms mean in the context of the Chanur novels?
spaceship terminology alliance-union
spaceship terminology alliance-union
edited 52 mins ago
DavidW
4,06911452
asked Sep 3 '17 at 3:03
Matthew ClineMatthew Cline
1855
edited 52 mins ago
DavidW
4,06911452
asked Sep 3 '17 at 3:03
Matthew ClineMatthew Cline
1855
edited 52 mins ago
DavidW
4,06911452
edited 52 mins ago
DavidW
4,06911452
edited 52 mins ago
DavidW
4,06911452
4,06911452
asked Sep 3 '17 at 3:03
Matthew ClineMatthew Cline
1855
asked Sep 3 '17 at 3:03
Matthew ClineMatthew Cline
1855
asked Sep 3 '17 at 3:03
Matthew ClineMatthew Cline
1855
1855
These terms are not a sci-fi specific. They show up in astronomy and aerial navigation as well. You should move this question to another SE forum.
– RichS
Sep 3 '17 at 3:37
This question would be more appropriate in the astronomy forum.
– RichS
Sep 3 '17 at 3:53
add a comment |
These terms are not a sci-fi specific. They show up in astronomy and aerial navigation as well. You should move this question to another SE forum.
– RichS
Sep 3 '17 at 3:37
This question would be more appropriate in the astronomy forum.
– RichS
Sep 3 '17 at 3:53
These terms are not a sci-fi specific. They show up in astronomy and aerial navigation as well. You should move this question to another SE forum.
– RichS
Sep 3 '17 at 3:37
These terms are not a sci-fi specific. They show up in astronomy and aerial navigation as well. You should move this question to another SE forum.
– RichS
Sep 3 '17 at 3:37
This question would be more appropriate in the astronomy forum.
– RichS
Sep 3 '17 at 3:53
This question would be more appropriate in the astronomy forum.
– RichS
Sep 3 '17 at 3:53
add a comment |
1 Answer
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Zenith is the highest point on the celestial sphere. It is directly above you.
Nadir is the lowest point on the celestial sphere. It is directly beneath you.
The terms zenith and nadir can be referenced from the local horizon on a planetary surface, but they can also be described in terms of a local observer or spacecraft out in space.
If you tilt your head left 20 degrees, your zenith is now 20 degrees offset from the horizon-line zenith. Likewise, if a spaceship rolls 20 degrees to port, its zenith is now 20 degrees from where it was before the course change.
Nadir and zenith are not appropriate for describing a star's north and south poles as described in the Chanur novels, since the terms are used in reference to an observer. It was not accurate for novels to describe the region above the sun's south pole as the nadir of our Solar System. That region is more accurately described as the south celestial region of a huge imaginary sphere centered on our sun.
As you can see from this picture, the zenith is above the observer on Earth, and the zenith does not align with the North celestial pole. Nor does the nadir align with the South celestial pole. They only align when the observer is at Earth's north pole.
answered Sep 3 '17 at 3:39
RichSRichS
19k17103263
add a comment |
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Zenith is the highest point on the celestial sphere. It is directly above you.
Nadir is the lowest point on the celestial sphere. It is directly beneath you.
The terms zenith and nadir can be referenced from the local horizon on a planetary surface, but they can also be described in terms of a local observer or spacecraft out in space.
If you tilt your head left 20 degrees, your zenith is now 20 degrees offset from the horizon-line zenith. Likewise, if a spaceship rolls 20 degrees to port, its zenith is now 20 degrees from where it was before the course change.
Nadir and zenith are not appropriate for describing a star's north and south poles as described in the Chanur novels, since the terms are used in reference to an observer. It was not accurate for novels to describe the region above the sun's south pole as the nadir of our Solar System. That region is more accurately described as the south celestial region of a huge imaginary sphere centered on our sun.
As you can see from this picture, the zenith is above the observer on Earth, and the zenith does not align with the North celestial pole. Nor does the nadir align with the South celestial pole. They only align when the observer is at Earth's north pole.
answered Sep 3 '17 at 3:39
RichSRichS
19k17103263
add a comment |
Zenith is the highest point on the celestial sphere. It is directly above you.
Nadir is the lowest point on the celestial sphere. It is directly beneath you.
The terms zenith and nadir can be referenced from the local horizon on a planetary surface, but they can also be described in terms of a local observer or spacecraft out in space.
If you tilt your head left 20 degrees, your zenith is now 20 degrees offset from the horizon-line zenith. Likewise, if a spaceship rolls 20 degrees to port, its zenith is now 20 degrees from where it was before the course change.
Nadir and zenith are not appropriate for describing a star's north and south poles as described in the Chanur novels, since the terms are used in reference to an observer. It was not accurate for novels to describe the region above the sun's south pole as the nadir of our Solar System. That region is more accurately described as the south celestial region of a huge imaginary sphere centered on our sun.
As you can see from this picture, the zenith is above the observer on Earth, and the zenith does not align with the North celestial pole. Nor does the nadir align with the South celestial pole. They only align when the observer is at Earth's north pole.
answered Sep 3 '17 at 3:39
RichSRichS
19k17103263
add a comment |
Zenith is the highest point on the celestial sphere. It is directly above you.
Nadir is the lowest point on the celestial sphere. It is directly beneath you.
The terms zenith and nadir can be referenced from the local horizon on a planetary surface, but they can also be described in terms of a local observer or spacecraft out in space.
If you tilt your head left 20 degrees, your zenith is now 20 degrees offset from the horizon-line zenith. Likewise, if a spaceship rolls 20 degrees to port, its zenith is now 20 degrees from where it was before the course change.
Nadir and zenith are not appropriate for describing a star's north and south poles as described in the Chanur novels, since the terms are used in reference to an observer. It was not accurate for novels to describe the region above the sun's south pole as the nadir of our Solar System. That region is more accurately described as the south celestial region of a huge imaginary sphere centered on our sun.
As you can see from this picture, the zenith is above the observer on Earth, and the zenith does not align with the North celestial pole. Nor does the nadir align with the South celestial pole. They only align when the observer is at Earth's north pole.
answered Sep 3 '17 at 3:39
RichSRichS
19k17103263
Zenith is the highest point on the celestial sphere. It is directly above you.
Nadir is the lowest point on the celestial sphere. It is directly beneath you.
The terms zenith and nadir can be referenced from the local horizon on a planetary surface, but they can also be described in terms of a local observer or spacecraft out in space.
If you tilt your head left 20 degrees, your zenith is now 20 degrees offset from the horizon-line zenith. Likewise, if a spaceship rolls 20 degrees to port, its zenith is now 20 degrees from where it was before the course change.
Nadir and zenith are not appropriate for describing a star's north and south poles as described in the Chanur novels, since the terms are used in reference to an observer. It was not accurate for novels to describe the region above the sun's south pole as the nadir of our Solar System. That region is more accurately described as the south celestial region of a huge imaginary sphere centered on our sun.
As you can see from this picture, the zenith is above the observer on Earth, and the zenith does not align with the North celestial pole. Nor does the nadir align with the South celestial pole. They only align when the observer is at Earth's north pole.
answered Sep 3 '17 at 3:39
RichSRichS
19k17103263
edited Sep 3 '17 at 8:01
answered Sep 3 '17 at 3:39
RichSRichS
19k17103263
answered Sep 3 '17 at 3:39
RichSRichS
19k17103263
answered Sep 3 '17 at 3:39
RichSRichS
19k17103263
19k17103263
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add a comment |
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These terms are not a sci-fi specific. They show up in astronomy and aerial navigation as well. You should move this question to another SE forum.
– RichS
Sep 3 '17 at 3:37
This question would be more appropriate in the astronomy forum.
– RichS
Sep 3 '17 at 3:53