Talk:Horizon

Mushroom cloud

Why does the horizon picture look like it has a mushroom cloud in the background? User:fresheneesz 15:10, 25 March 2025 (UTC) (this is the date the date stamp was added, which was long after the date of the original posting, which had no date - Butwhatdoiknow (talk) 15:11, 25 March 2025 (UTC))

Space shuttle photo

I am confused by the space shuttle photo. If it is the Earth's horizon we are seeing, why is it curving downward, rather than upward as the horizon, as we view it, usually does?

Apparently, because what we see in the photo is not the horizon as we normally view it from a position on or close to the Earth's surface, but from up in space, where it is not the horizon as we think of it, but simply the curvature of the Earth.

Is that too considered the "horizon," meriting inclusion of the photo in this article? That seems counterintuitive.

Or, does it mean that the terms "horizon" and "Earth's curvature" are in fact entirely interchangeable? And when from yet much higher up in outer space the *entire* Earth is seen, what is being observed is simply a "360-degree horizon"? That doesn't seem right at all. 🤔 Toddcs (talk) 18:22, 12 October 2023 (UTC)

The space shuttle has its top side toward earth, hence the horizon looks upside down. Constant314 (talk) 20:05, 12 October 2023 (UTC)

"360-degree horizon" is not a question Please delete the question mark. Even from far out in space, the maximum of just slightly less than one hemisphere of Earth can be seen. The other hemisphere is obscured as it is behind the visibe hemisphere Iceiggle (talk) 12:46, 22 February 2025 (UTC)

Horizon dip

The "Horizon dip" (a/k/a "sea dip") optical illusion redirects to #Effect of atmospheric refraction in this article. However, neither term appears in the text. Nor is the illusion explained in laymen's terms. I'd boldly fix these issues, but I am an actual layman. Would a more knowledgeable editor please improve the article with this information?

Here are a couple of sources (which may not reach meet Wikipedia's standards) -

• https://aty.sdsu.edu/explain/atmos_refr/dip.html
• [https://www.quora.com/Why-does-the-sea-look-so-high-on-the-horizon]

- Butwhatdoiknow (talk) 03:31, 25 March 2025 (UTC)

geoid

There are a couple of incorrect and misleading statements in this article. One (in Refraction section) claims "If the Earth were an airless world like the Moon, the above calculations would be accurate." Well, maybe. Accuracy is here completely subjective. No definition is given. It's (apparently?) assumed that the air to the horizon is clear, but how often is that the case? Fog and particulates often obscure the horizon. There is no explicit discussion of the fact that Earth is NOT a sphere and not even an ellipsoid of revolution. How can calculations be "accurate" if they are based on incorrect assumptions? (The actual question is how accurate are they?) What is the worst case difference between the simple formula given and the actual horizon? What is the best case? How about corrected to an ellipsoid? Also, no mention here that "sea level" is different from the level the ocean is actually at. The actual sea level is not the same as the reference sea level. (How much do they differ? I'm not sure, but the maps I've seen of sea level height vs reference showed differences of meters, iirc. And that's a lot if you're only considering heights above sea level of meters.) So, to sum up, clear (enough) air is a necessary condition, the calculations are based on the assumption that it's a sphere, and the discrepancy between actual sea level at a given point and reference sea level needs some discussion.98.19.179.27 (talk) 15:57, 10 May 2025 (UTC)

WP:SOFIXIT. - \\'cԼF 11:51, 15 May 2025 (UTC)

Second sentence

"This border divides all viewing directions based on whether it intersects the relevant body's surface or not." Can anyone explain this sentence? If so, we can use that explanation to make it clearer. If not, we should probably remove the sentence. - Butwhatdoiknow (talk) 05:08, 10 July 2025 (UTC)