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【Regarding the ‘Longitude’ of the Rotational Axis..】 To specify a location on the Earth's surface, two variables—latitude and longitude—are required. Similarly, to specify the direction of the Earth's rotational axis in space, two angles are needed. The fact that it is tilted approximately 23.5 degrees relative to the orbital plane corresponds to the angle of ‘latitude.’ However, even though the rotational axis spins like a top, that latitude does not change; the variable corresponding to this degree of freedom is the angle corresponding to ‘longitude.’ When viewed from above, the Earth's rotational axis forms an angle of approximately 13.8 degrees with the major axis of the ellipse. This angle is the longitude of the rotational axis. Even if we ignore this angle and assume that the rotational axis is parallel to the major axis at the apohex and perigee when viewed from above the ellipse, there is no problem in explaining the fundamental cause of the seasons and roughly distinguishing the four seasons. However, the angle of ‘13.8 degrees’ is not entirely negligible in terms of magnitude itself, and it has a significant impact on distinguishing the actual seasons. However, this ‘longitude of the rotational axis’ was not considered in the video. During the considerable time spent producing the video, I felt that this part could not be omitted and intended to include it. But as I continued the discussion, I realized that this single variable significantly increased the length and complexity of the video. Ultimately, judging that it might hinder the understanding of more important topics, I omitted that part. If you would like an analysis that considers the longitude of the rotational axis, please refer to the blog post linked below, ‘A Surprisingly Simple Method to Calculate Earth’s Orbital Eccentricity (2).’ 【Rotation and Orbital Direction】 When viewing the elliptical orbit from the North Pole, both the Earth’s revolution and rotation are counterclockwise, meaning they rotate in the same direction. However, I used a clock as an example to intuitively explain Kepler’s laws, and for this reason, I changed the direction of the revolution to clockwise. Consequently, in the video, revolution is visualized as rotating clockwise and rotation as rotating counterclockwise. Please note that while this does not conflict with the main logical progression of the video, directions different from reality were adopted for the sake of explanation. 【References】 ⎯ ‘A certain article related to climate’ mentioned at the beginning of the video: Milankovitch (Orbital) Cycles and Their Role in Earth's Climate (https://climate.nasa.gov/news/2948/mi...) ⎯ Shadow simulator: https://andrewmarsh.com/apps/staging/... ⎯ Sun/Earth/Moon 3D models: https://science.nasa.gov/learn/heat/r..., https://science.nasa.gov/resource/ear..., https://science.nasa.gov/resource/ear... ⎯ How a fake Kepler portrait became iconic (https://arxiv.org/pdf/2108.02213.pdf) ··· Although the portrait of a figure holding a compass like chopsticks is widely used as the portrait of Kepler, it is said that the person in the portrait is not Kepler. It is known to be a 19th-century copy made by an unknown artist of a portrait presumed to have been painted in the early 17th century, and it is considered more likely that the figure in it is Michael Maestlin, who was Kepler's mentor. ⎯ Solar System zoom-out scene : Universe Sandbox (http://universesandbox.com/) ⎯ Sedna : https://en.wikipedia.org/wiki/90377_S... ⎯ Goseck Circle : https://en.wikipedia.org/wiki/Goseck_...