<story><title>The equinox is not when day and night have equal lengths</title><url>https://www.scientificamerican.com/article/the-equinox-is-not-what-you-think-it-is/</url></story><parent_chain></parent_chain><comment><author>furyofantares</author><text>I find it more satisfying and clearer to say it&amp;#x27;s when day&amp;#x2F;night are the same length everywhere on earth&amp;#x2F;for everyone on earth.&lt;p&gt;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.&lt;p&gt;Within that framework you could bring up pendantry how  &amp;quot;definitions&amp;quot; of day&amp;#x2F;night mean this doesn&amp;#x27;t imply day and night are each 12 hours. Actually I find such pedantry more interesting in this framework; it&amp;#x27;s just clearer that we&amp;#x27;re saying globally there is always more day than night under this particular definition.&lt;p&gt;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&amp;#x27;t hover in that point of the orbit for 24 hours.</text></comment>
<story><title>The equinox is not when day and night have equal lengths</title><url>https://www.scientificamerican.com/article/the-equinox-is-not-what-you-think-it-is/</url></story><parent_chain></parent_chain><comment><author>Retric</author><text>For an article this pedantic they still miss several details. “If we measured the day starting and ending when the sun’s center breached the horizon, we’d be fine; day and night would be equally parsed.”&lt;p&gt;It then list a few caveats but that’s not sufficient as the sun is going to cross the the equator at some random point in the day say 2:15:45 pm which means it’s not over the equator at sunrise and sunset thus distorting the day.  The horizon is generally defined based on local terrain not the more abstract true horizon.  Earth isn’t a perfect sphere rotating at a constant rate etc etc.&lt;p&gt;It’s got some amusing bit’s of trivia, but I don’t think anyone’s definition is going to actually change.</text></comment>