Caption: An animation of the Earth's orbit around the Sun.

Features:

1. The animation is not-to-scale.

2. Over relatively short time periods like a year and a human lifetime, the direction of the Earth's axial tilt is constant with respect to the fixed stars, and therefore also with respect to ecliptic pole which is perpendicular to the ecliptic plane which is the plane of the Earth's orbit.

   Recall that saying "with respect to the fixed stars" is a conventional way of saying with respect to the fundamentally absolutely unrotating observable universe with respect to which all inertial frames do NOT rotate---except maybe in very strong gravitational fields like near black holes???---but yours truly has to guess about this since no one explicates this factoid. The best explication so far (and it does NOT say much) is Wikipedia: Inertial frame of reference: General relativity.

3. The varying average amounts of solar intensity (AKA insolation AKA (solar energy per unit time per unit area) received by the Northern Hemisphere Southern Hemisphere are the causes of the seasons.

4. The Northern Hemisphere is in summer when the north end of the Earth's axis is tilted toward the Sun and in winter when it is tilted way.

5. In between summer and winter, one has the in-between seasons, spring and fall.

6. The Southern Hemisphere is the mirror-image case to the Northern Hemisphere.

7. For a slower equivalent to the animation, see the video Earth Sun Relations | 1:11 in Earth season videos below (local link / general link: earth_season_videos.html).

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