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Is there a single generic term to refer, either collectively or arbitrarily, to both sunrises and sunsets?

I'm looking for something that could be used in the same vein as twilight can be used (formally or informally) to refer to both the pre-sunrise dawn period and the post-sunset dusk period, without specifying which.

I'm aware of the concept of a golden hour within the photography and cinematography communities, but I'm looking for something which refers more to the specific astronomical event, as a particular instant in time, while still being agnostic to the direction the sun is going.

Edit: To clarify, I'd like something that could describe, even informally, any or all of:

  1. Instants when the sun is exactly at the horizon, or 0°,
  2. Periods when the sun is near the horizon on either side, e.g., –2° to +2°, or
  3. Periods when the sun is near the horizon, but strictly above it, e.g., 0° to +2°.

I am aware of the various astronomical definitions of twilight, but unfortunately none of them meets any of these.

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There's a beautiful Sanskrit word that describes what you are looking for. It is called "sandhya". –  moonstar2001 Jan 5 at 8:04
    
This may not be what you're looking for either, but "green flash" or "green ray" refers to an optical phenomenon that occurs for an instant before or after sunrise or sunset. See en.wikipedia.org/wiki/Green_flash. Eric Roemer made this phenomenon the symbolic center of Le Rayon Vert (aka Summer), a film he directed in 1986—recommended if you like Roemer's other films. –  Sven Yargs Jan 6 at 3:44

2 Answers 2

The word twilight actually means what you're looking for:

twilight, n.: the light from the sky between full night and sunrise or between sunset and full night

Animals that are active during twilight are said to be crepuscular, so if you're looking for an adjective to apply to that period, crepuscular (which is itself derived from the Latin for twilight) should serve.

Edit: Lacking the context in which you wish to use the term you're looking for, I can offer these suggestions:

Sunset/sunrise occur at the instant that the sun's upper limb is tangent to the horizon. You could then, for example, have science officer of some enterprising starship reporting, "Two degrees to limb tangency, Captain" to mark some impending sunrise/sunset/moonrise/moonset/et ceteraset.

Sunset/sunrise occur at a precise zenith distance of 90.8333 degrees. You could coin a term for this value, so that the same science officer could report, "Two arc seconds from zenith distance alpha, Captain."

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Please re-read my question; I want to describe specific events at specific instants in time, not the periods of time surrounding those instants nor the light from them. –  Tim Parenti Jan 5 at 5:20
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I think he’s looking for the time when the sun is in sky, not below the horizon like with twilight. So he wants something for the time right after dawn and the time right before dusk. So when a star is near the horizon, but above it. –  tchrist Jan 5 at 5:20
    
@tchrist Right. We use sunrise to refer to the precise time at which the sun comes up from the horizon, as well as more informally to the period of time approximating that instant. That's the kind of thing I'm going for. –  Tim Parenti Jan 5 at 5:24
    
Both sunrise and sunset occur at the precise instant that the sun's upper limb is tangent to the horizon (usually an idealized one). I haven't been able to to find a general term for that instant of tangency. –  Gnawme Jan 5 at 6:15
    
@Gnawme It's quite possibly a lacuna. Or perhaps just a very technical term. I don't know... but I guess that's why I'm asking! –  Tim Parenti Jan 5 at 6:21

Nautical twilight occurs right after civil twilight in the evening, and right before civil twilight in the morning. This phase occurs when the center of the sun is between 6 and 12 degrees below the horizon in the morning and evening. This period also usually lasts around 30 minutes and the primary color cast across the atmosphere is usually a deep blue tone with still noticeable orange and yellow hues left over from the fading sun. The horizon is still visible during this time... The light has started to dissipate quickly and silhouettes are going to be more prevelent... Details will be harder to make out during this time but there is still some remaining light on the horizon from the sun.

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