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

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

1 Answer 1


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.

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    $\begingroup$ Thanks, It seems Orbital Plane is not constant as earth do not return to the same location after one complete revolution( year ) youtube.com/watch?v=82p-DYgGFjI&t=49s $\endgroup$
    – puzzled
    Commented Mar 23 at 16:21
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    $\begingroup$ 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) $\endgroup$ Commented Mar 23 at 16:38
  • $\begingroup$ to ask for further clarification... does rotation axis precession affect ecliptic plane in any way? $\endgroup$
    – BradV
    Commented Mar 23 at 22:36
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    $\begingroup$ There's a lot of confusing nonsense on YouTube about the orbits of planets. $\endgroup$
    – ProfRob
    Commented Mar 24 at 17:23
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    $\begingroup$ @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. $\endgroup$
    – RisingZan
    Commented Mar 25 at 16:32

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