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Comment by nategri | Hacker News Reader

> A more circular orbit of Earth around the sun — leading to years with no great difference between summer and winter — might have also helped doom most of the fish.

Oh man please do not say this without additional clarification. People are confused enough as it is about what causes seasons.

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Earth's orbital eccentricity has nothing at all to do with its seasons. It's nearly a perfect circle right now. The reason Earth has seasons is because of the axial tilt relative to the plane of rotation. In the northern summer, the northern hemisphere is angled towards the sun, and in the northern winter, it's angled away. This repeated incorrect claim in the article is frustrating, because it's otherwise describing a fascinating theory.

For people who don't know -- earth's orbit is more like a circle than an elipse. The tilt of the earth is responsible for most seasonal variation we see on earth. IIRC, Mars has more of a difference between ahelion and perihelion and that impacts seasonal variation there much more.

The term here, if anyone wants to look into it, is "orbital eccentricity". Here's a table listing the eccentricities of the various planets: http://www.enchantedlearning.com/subjects/astronomy/glossary...

I found a couple of papers about correlations between Earth-orbit perturbations and ice ages; submitted separately:

https://news.ycombinator.com/item?id=16533837

It's sad that people who write such articles know so little science.

No, that's not at all a problem. The problem is how little they bother researching what they write about.

When you lack requisite background, research doesn't help very much. It's like cramming for finals, when you've done no work during the semester.

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