# a question about earth's orbital plane

Discussion in 'Physics & Math' started by TonyYuan, Sep 29, 2021.

1. ### TonyYuanGravitational Fields and Gravitational WavesRegistered Senior Member

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Does anyone know the angle between the earth's orbital plane and the direction of the sun's orbital velocity? I don't think it's exactly 90 degrees.

Thanks.

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3. ### JerimiahRegistered Member

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Hello, isn't this something you could google ?

In reality angles are virtual scalars and vectors , the angles been relative to our space-time xyzt coordinate system .

Additionally if we were been specific about angles from the earths surface , each angle is different , var x !

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5. ### foghornValued Senior Member

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Google ''Solar Apex'' for the direction of sun in space.
Google''Angle between Ecliptic and Solar Apex''..I don't know what will appear.
That's me out of ideas.

Last edited: Sep 29, 2021

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7. ### mikelizziRegistered Senior Member

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9. ### JerimiahRegistered Member

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Hello Janus , I am unable to upload a diagram but from my position in the world , I observe the Sun rise in the East , it follows a curved path South before curving and setting in the West . Admitting I have no special equipment and I am relying on geometrical landmarks for accuracy but to me the Sun seems to take a ''dip'' and a ''curve'' before rising in the East again , not a perfect ''circle'' like your provided link shows ?
To try and describe what I observe , when the Sun sets in the West it then drops and follows a sort of ''u'' path back to the East ?

10. ### Janus58Valued Senior Member

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The diagram I provided dealt with the Earth's orbit around the Sun. What you are describing is the Sun's apparent path across the sky due to the Earth's rotation. This greatly depends on your latitude. It is you that are traveling in a circle, and viewing the Sun along a line that does not lie on that circle.

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11. ### JerimiahRegistered Member

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Thank you Janus , I did actually forget to equate for the earths spin which has an axial tilt and is anti-clockwise . I think Einstein may be confusing me with the simultaneity . Relative to the Sun the Earth is moving and relative to the Earth the Sun is moving ! How do we derive that the Sun and Earth are both moving?

12. ### TonyYuanGravitational Fields and Gravitational WavesRegistered Senior Member

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The rotation of the sun is tilted by 7.25 degrees to the ecliptic, and this value does not vary over time.
Does this mean that the angle between the equatorial plane of the sun and the ecliptic plane is 7.25 degrees?

I don’t know if the direction of the sun’s rotation axis can represent the direction of the sun’s orbital velocity?

13. ### Janus58Valued Senior Member

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You use a common reference, for example the stars. Relative to the stars, the Earth orbits the Sun in 365.256363004 hrs( sidereal year), and it rotates on it's axis in 23.9344696 hrs( sidereal day). Since the Earth has travels a bit around the Sun in the time it takes to rotate, it has to rotate a bit more than one full rotation relative to the stars to same the same point of it surface line up with the Sun again, and you end up with a "solar" day of 24 hrs.*
Not that there is anything special about using the stars as our reference, it is just the most convenient reference in this case.

*Since the Earth orbits in a slightly elliptical orbit, the actual length of the Solar day changes throughout its orbit and just averages out to very close to 24 hrs and it isn't even exactly that because of changes in both the Earth's rotation and orbit over time.

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14. ### JerimiahRegistered Member

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Is Einstein incorrect ? How do we know the Sun and stars aren't moving relative to the earth ?

15. ### mikelizziRegistered Senior Member

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Sounds like you are interested in the orbit of the Sun around the center of the galaxy. In that case, the post from Janus would be appropriate, not mine.

16. ### Janus58Valued Senior Member

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While you could assume that the Earth was stationary and everything else was spinning around it. You would have invoke a pseudo-gravitational field to explain why it was all constrained to traveling in circles around the Earth. It also makes the calculations dealing with all the individual motions much more complex. Thus, while you are perfectly free to work from what frame of reference you choose, it just makes sense to work from the one that makes things the easiest for you.

17. ### foghornValued Senior Member

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Tony, are you trying to find the angle between the ecliptic (the plane of the Earth's orbit) and the Sun's orbital plane around the galaxy?

Janus.
If Tony is looking for the angle between the planes of the Sun's orbit about the galaxy and Earth's orbital plane, then would that be degrees 53.43 degrees ??

This is the ecliptic coordinates of the Solar Apex 271.79° longitude, +53.43° latitude.
https://en.wikipedia.org/wiki/Solar_apex

Last edited: Sep 30, 2021