Talk:Terminator (solar)

Merged entry from Terminator disambiguation page with solar terminator line and moved to Terminator (solar). We could also consider moving the page to Terminator (astronomy) — now we are starting to see planets in other solar systems its only a matter of time when Sol-centric references are seen as POV. -- Solipsist 13:39, 20 Jan 2005 (UTC)

That picture is a total fake. See http://www.snopes.com/photos/sunset.asp I'm going to remove it; if someone can think of a good reason to put it back, please do. Trevor 00:19, 20 April 2006 (UTC)

The photo has since been restored, with a caption that clarifies it as a composite; not a "fake". It still has value to this page. --Bossi (talk • gallery • contrib) 17:25, 1 November 2008 (UTC)

The fuzzyness of the terminator can also be caused by the light source (e.g. the Sun) being larger than a point source. As the sun sets, less and less of it is visible from a given point, gradually reducing the amount of light impinging upon that point. (Not sure how to rewrite the text, though...) --Dan Griscom 16:19, 8 February 2007 (UTC)

It doesn't necessarily have to be bigger; it just has to have any size greater than a 1-dimensional point (or a 2-dimensional arc with the same curvature as the skyline). However, an atmosphere will scatter light and remain illuminated even after the light source has passed beyond the horizon: hence, it's certainly a key indicator. I'll tweak the sentence a bit. --Bossi (talk • gallery • contrib) 17:25, 1 November 2008 (UTC)

While one half of the Earth is illuminated at any point in time, [...]

Solar eclipses make this half even less than a half. --Abdull 10:33, 2 December 2007 (UTC)

I've noted the exception in the article. --Bossi (talk • gallery • contrib) 17:25, 1 November 2008 (UTC)

Pretty much every English-speaker who searches for Twilight Zone wants to know about the TV Show. It is very weird and nonsensical for it to redirect to this page! —Preceding unsigned comment added by 201.6.34.114 (talk) 15:54, 15 April 2008 (UTC)

An anonymous user got away with doing it. I have changed it back. –King Bee ^{(τ • γ)} 14:54, 24 April 2008 (UTC)

Hello. How come this doesn't go to the show? —Preceding unsigned comment added by CuttingRoomFloor (talk • contribs) 08:47, 25 June 2008 (UTC)

Is there a general value for how wide(e.g. in km) the twilight zone is? What I mean is the length between the point from where the 'gradient' starts and where it ends. I could imagine it is 200 to 300 km wide but it would be nice to have some scientific numbers. --sys2074 (talk) 18:34, 19 May 2008 (UTC)

Hard to say offhand; it would certainly depend on the planet's radius, the star's radius and distance, the density and makeup of the atmosphere (in other words, how much it scatters light) and a number of other factors. Unfortunately I don't have the figures you'd need to do those calculations, otherwise I'd do a worked example for earth. Perhaps someone else knows how it could be calculated theoretically? Torak (talk) 00:32, 7 July 2008 (UTC)

In fact it's kind of hopeless analytically: you're asking for the brightness of sunlight as a function of time at any point on the Earth. Even mountains, for example, cast shadows that move the terminator locally. —Preceding unsigned comment added by 132.206.92.45 (talk) 20:42, 26 August 2008 (UTC)

Can't a calculation be given for the thickest and narrowest the terminator can be on earth? without obstacles like mountains affecting it? Let's say, in plain terrain at sea level?Undead Herle King (talk) 08:52, 29 June 2012 (UTC)

The page at the moment says "The seasons impact the location of the terminator line most dramatically." How accurate is this, astronomically and semantically? Surely it's the planet's angle to the sun that affects the location of the terminator, which in turn causes what we perceive as seasons? Fair enough, in practice the effect is the same, but strictly speaking, wouldn't it be more accurate to say that the seasons are the result of the terminator's location, which is in turn the result of the planet's axial tilt? Torak (talk) 00:28, 7 July 2008 (UTC)

I'm rephrased this statement and expanded upon much of the information. --Bossi (talk • gallery • contrib) 17:25, 1 November 2008 (UTC)

I deleted the image from time.gov (showing the terminator on Jan 3), because it is incorrect. It shows light symmetrically divided between the two hemispheres. However, at that time of year (Northern winter), there should be a band at the top (around the north pole) that light does not reach into, and at the bottom (around the south pole) there should be a band in continuous light. Compare to the websites at http://www.fourmilab.ch/cgi-bin/Earth or http://aa.usno.navy.mil/data/docs/earthview.php, which generate correct images. Wingedsubmariner (talk) 05:16, 12 December 2009 (UTC)

I undid my edit: I was wrong, graph didn't extend as far as I thought. Wingedsubmariner (talk) 20:59, 16 December 2009 (UTC)

The terminator is lined up pole to pole on the equinoxes, right? My reasoning is that the sun sets at one pole and rises at the other. On the northern solstice, the terminator goes from lat. 66.5 S, overlaps the north pole (shrouding it in darkness) and meets at lat. 66.5 N. On the southern solstice, the terminator runs from lat. 66.5 N, overlaps the south pole and meets at lat. 66.5 S.

I would like these facts to be confirmed before I add them. --67.1.81.68 (talk) 03:57, 6 March 2012 (UTC)

Comments go here. — Preceding unsigned comment added by 71.236.136.184 (talk) 22:51, 4 September 2013 (UTC)
I agree with this proposal. The Lunar Terminator article is a stub, and would be better suited as a subdivision of this one rather than a standalone piece. TheDorianMode (talk) 23:23, 6 September 2013 (UTC)

Agreed, better organization. MachoCarioca (talk) 21:22, 18 December 2013 (UTC)

Disagree. While the lunar terminator is indeed a type of solar terminator, the fact that it can easily be observed with the naked eye from earth makes it unique among all other terminators. I suggest keeping it a distinct article.Jstuby (talk) 14:29, 26 April 2014 (UTC)

Agreed - this article is a WP:FORK since the phenomenon exists everywhere in the Solar system - Anonimski (talk) 17:42, 17 June 2015 (UTC)  Done

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The user below has a request that an edit be made to Terminator (solar). That user has an actual or apparent conflict of interest. The requested edits backlog is very high. Please be extremely patient. There are currently 704 requests waiting for review. Please read the instructions for the parameters used by this template for accepting and declining them, and review the request below and make the edit if it is well sourced, neutral, and follows other Wikipedia guidelines and policies.

Conflict-of-interest declaration: I am a co-author of the source I propose below, and my co-author is an officer of a company active in this area. I am therefore not editing the article directly. Full disclosure is on my user page. Please treat this as a suggestion only, including whether the source is suitable at all.

Issue: The final paragraph of Terminator (solar)#Scientific significance carries no citation, and gives only the electrical power rationale for dawn-dusk orbits: continuous illumination, prolonged battery life, and sensor placement on the dark side. It omits the thermal rationale, which is a separate consequence of the same geometry. Because the orbital plane holds a roughly fixed angle to the Sun, a spacecraft can keep radiators pointed away from the Sun toward cold space, and it avoids the thermal cycling that comes from crossing into and out of Earth's shadow roughly every 90 minutes.

Proposed change: after the existing sentence ending "...install the relevant sensors on the dark side of the satellite.", append:

The same geometry also has thermal consequences: a spacecraft in a dawn-dusk orbit can hold its radiators in a near-constant anti-Sun attitude facing cold space, and largely avoids the thermal cycling produced by repeatedly entering and leaving Earth's shadow. This has been noted as an attraction of the orbit for power-intensive payloads, whose waste heat can only be rejected by radiation.<ref>{{cite report |last1=Ryan |first1=Patrick Spaulding |last2=Westerdahl |first2=Ryan |date=14 August 2026 |title=The Terminator Orbit |publisher=Social Science Research Network |ssrn=7280738}}</ref>

Link to the source: the paper is at https://ssrn.com/abstract=7280738 if it helps to look at it before deciding.

Note on the source: it is an SSRN working paper and has not been peer reviewed, so it may not meet WP:SCIRS. I propose it because the paragraph is presently unsourced, but the underlying point is not controversial and reviewers may prefer a peer-reviewed thermal-control or sun-synchronous-orbit design reference instead. Adding the sentence with a better source, or with no citation to my paper at all, would still improve the article, and I would consider that a good outcome. If it is declined on sourcing grounds, I would welcome a pointer to what would clear the bar. Vaquerito (talk) 07:29, 19 August 2026 (UTC)