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I am asking basic question on trying to understand on tilt. I know if I (as a human) tilt when standing on feet, my tilt will be in relation to gravity.

For Earth, I am not able to understand, what is the relative object of the earth tilt is. I am not asking how does north hemisphere or south hemisphere gets more/less sun light and when.

If there are visual model videos that this group can point out that will be helpful.

one Example on Phases of moon

puzzled
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    It is tilted relative to the plane of Earth's orbit (called the ecliptic). – Greg Miller Mar 23 '24 at 13:50
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    https://youtu.be/xVERe-hc3G8?t=13 shows a model that seems to visually clarify the Orbital Plane . https://youtu.be/oW2GT48ZLwA?t=978 shows model along with other motions that are occurring at same time – puzzled Mar 23 '24 at 16:51

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The orbit of the Earth around the Sun defines an orbital plane.

The equator of the Earth is (currently) tilted at an angle of 23.4 degrees to this orbital plane.

Or to put it another way, the spin-axis of the Earth is tilted by 23.4 degrees to a vector defining the orbital angular momentum.

ProfRob
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    Thanks, It seems Orbital Plane is not constant as earth do not return to the same location after one complete revolution( year ) https://www.youtube.com/watch?v=82p-DYgGFjI&t=49s – puzzled Mar 23 '24 at 16:21
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    The orbital plane is very very very close to being constant. There's all sorts of precessions, but they're on the time scale of tens of thousands of years, so incredibly slow compared to one orbit around the Sun (aka, one year) – ScienceSnake Mar 23 '24 at 16:38
  • to ask for further clarification... does rotation axis precession affect ecliptic plane in any way? – BradV Mar 23 '24 at 22:36
  • @puzzled can you clarify what in that video says that Earth does not return to the same position after one year? – jcaron Mar 24 '24 at 16:40
  • @jcaron https://youtu.be/82p-DYgGFjI?t=15 ( that is from 00:15 to 0:25) – puzzled Mar 24 '24 at 17:03
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    There's a lot of confusing nonsense on YouTube about the orbits of planets. – ProfRob Mar 24 '24 at 17:23
  • @puzzled: while qualitatively most things in that video might check out, everything visual in it is so highly exaggerated for visual effect, so that for all practical purposes (read: human timescales), the effect of all those cycles can be ignored. Exhibit A: how elliptic Earth's orbit is around the sun: https://en.wikipedia.org/wiki/Earth%27s_orbit#/media/File:EarthsOrbit_en.png – ojdo Mar 25 '24 at 13:58
  • The diagram at the very end of the video is REALLY exaggerated. It makes the orgbit look like a spirograph design. – Barmar Mar 25 '24 at 15:15
  • @puzzled When playing a record on a phonograph, the needle moves inward towards the center of the record, but it remains on the same plane. In the same way, the earth can be closer to or farther from the sun while remaining in the orbital plane. – JimmyJames Mar 25 '24 at 15:57
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    @puzzled. The actual period of revolution is slightly more than one year, which is why we have leap years to adjust our calendar. If you want to get more pedantic, we never return to the same position because the entire solar system is moving through the Milky Way, and the Milky Way is moving through the extragalactic void. – RisingZan Mar 25 '24 at 16:32