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Comment by furyofantares | Hacker News Reader

I find it more satisfying and clearer to say it's when day/night are the same length everywhere on earth/for everyone on earth.

For me that prompts thinking about the earth with its tilt in relation to the sun and the two points in its orbit where that could be true.

Within that framework you could bring up pendantry how "definitions" of day/night mean this doesn't imply day and night are each 12 hours. Actually I find such pedantry more interesting in this framework; it's just clearer that we're saying globally there is always more day than night under this particular definition.

It also IMO prompts the even more interesting pedantry discussed in this thread about it crossing this point at some random time during the day, we don't hover in that point of the orbit for 24 hours.

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It's my go to fun fact whenever the situation is suitable for it. People often have never realized this.

(My other fun fact is that South America in its entirety lies East of Florida, and not below North America, most people memorize South America as being completely South of North America.)

Florida is also further west than most people realize, as Miami is longitudinally close to Cleveland, OH rather than New York City.

And, while on the subject - Norway is squarely in Western Europe, no?

Yet the town of Kirkenes in arctic Norway (somewhere around 70 degrees latitude) lies to the east of Istanbul.

What were the odds, got this tweet today https://twitter.com/Locati0ns/status/1705703590181187640?t=2...

> The entirety of continental South America lies east of Michigan" means that, in terms of geographical positioning on the Earth's surface, all of the landmass of South America is located to the east of the state of Michigan in the United States. This is a factual statement based on the Earth's geography. It highlights the vast eastward extent of South America compared to the location of Michigan in North America.

My geographic fun fact is my tiny Canadian province of Prince Edward Island (PEI) is the only Canadian province that doesn't border another country (but there is one territory that also doesn't border any country).

From British Columbia (BC) on west coast to New Brunswick (NB) and Nova Scotia (NS) on the East coast they all have a southern border with the USA. NS has a maritime border with the USA.

Newfoundland and Labrador border two countries although technically each is not what you think. To its south the island of Newfoundland borders France via the small cluster of islands which are a territory of France called St. Pierre and Miquelon. The Labrador border is an eastern maritime border with Denmark/Greenland.

Not a province but the territory of Nunavut also border Greenland/Denmark. It even has a land border via Hans Island a now shared island which Canada and Denmark used to both "fight" over.

The Yukon in the north-west borders the USA state of Alaska.

That leaves Northwest Territories (NWT) it has no border with any nation just its territory neighbours and the prairie provinces to the south.

> South America in its entirety lies East of Florida

Miami, FL: 80.2W Manta, Ecuador: 80.7W

It's close, but not quite.

I was curious, so I calculated what this distance would be in kilometers. At 2 degrees lattitude (lattitude of Ecuador), a difference of 0.5 degrees longitude translates to 55.6 kilometers.

Similarly ... the entire state of Maine, even its very north-most point, is to the south of Seattle's even southern-most point. A lot of US maps are tilted a few degrees, especially schoolroom maps, making the East coast and Maine seem much further north than it is.

It’s amazing how far north Seattle is, and at the same time, how temperate it is. Seemingly less than 8 hours of daylight in the winter and 16 hours of daylight in the summer are amazing.

After growing up in Wisconsin, Seattle seasons were so refreshing.

It’s the marine climate and most weather fronts move in from the ocean. When it does get relatively cold, it’s because of a front moving down from Canada.

The ocean helps. Vancouver, BC is even a bit further north and it’s the same.

One year I was there the flowers were blooming in late January. The middle of a Canadian winter.

Vancouver is Canada for beginners, weather-wise.

My more local fun fact: I live on the North Shore of Montreal, and I have friends that live on the South Shore, but they actually live more north than me.

My favorite geographic fun fact is that Maine is the closest state to Africa.

> I find it more satisfying and clearer to say it's when day/night are the same length everywhere on earth/for everyone on earth.

By the definition given in the article, that isn't true either. They point out that the equinox is in fact the point when day and night are of equal length as long as you define them in a consistent way. But if you instead define day as "whenever the sun is visible" [or would be visible in the absence of clouds], day and night aren't equal on the equinox.

But, if that's your definition of "day", it can never be the case that day and night are the same length everywhere on earth. The presence of mountains will affect when it is or isn't "day".

1. It's nowhere near night time the moment the sun sinks halfway past the horizon. It's around early evening. Only on a planet with no light-scattering atmosphere does night being at the completion of sundown. And even then, since the star is larger than the planet, more than 50% of the planet is illuminated: night is nevertheless shorter.¹

2. Did you consider the poles?

1. Someone claiming to be a mathematician posted some calculations on quora.com claiming that 50.23% of the Earth is illuminated directly due to the relative size of the Sun and the Earth. https://www.quora.com/What-percentage-of-planet-earth-is-ill...

It's the point where day and night would be the same length everywhere IF the earth stopped moving around the sun and just kept spinning.

Each point along a line of latitude is going to experience slightly different lengths of the day or night when the earth crosses the equinox point.

> I find it more satisfying and clearer to say it's when day/night are the same length everywhere on earth/for everyone on earth.

...except at the poles! (There the sun will appear to be moving along the horizon, and there is no day/night in the usual sense.)

And when you take the pedantry into account (top vs centre of sun, refraction) the length of the day/night is no longer the same around the globe, since the effect in terms of time is different at different latitudes.

Haha yeah his definition is from a perspective of need of structural consistency the rest of us wants the definition of day to be useful and represent when it’s light

Assuming a perfect sphere which earth is not ?

Equinox is when the Earth's axis of rotation is perpendicular to the path from Earth to Sun.

That is, when the poles are neither tilting "towards" the Sun (which happens in summer) nor "away" from the sun (which happens in winter).

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