<p><strong>Answer:</strong></p>
<p>PM 2Ring posted the answer in the above comment. The direction of each planet's rotational axis in <a href="https://en.wikipedia.org/wiki/Equatorial_coordinate_system" rel="nofollow noreferrer">RA/Dec</a> can be found in the table here: <a href="http://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies" rel="nofollow noreferrer">en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies</a>.</p>
<p><strong>Explanation:</strong></p>
<p>Astronomers have defined a coordinate system on the <a href="https://en.wikipedia.org/wiki/Celestial_sphere" rel="nofollow noreferrer">Celestial sphere</a>, with z-axis coincident with Earth's North Pole, and x-axis pointed to the <a href="https://en.wikipedia.org/wiki/First_Point_of_Aries" rel="nofollow noreferrer">First Point of Aries</a> (aligned with the vernal equinox). Two angles define a point on the celestial sphere: right ascension and declination are analogous to longitude and latitude respectively as shown from this <a href="https://en.wikipedia.org/wiki/Right_ascension" rel="nofollow noreferrer">wikipedia</a> plot.</p>
<p><a href="https://i.sstatic.net/MtLqn.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/MtLqn.png" alt="enter image description here" /></a></p>
<p><strong>Example:</strong></p>
<p>Uranus' North Pole direction had RA/Dec of 257.31, −15.18 degrees according to the <a href="https://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies" rel="nofollow noreferrer">wikipedia table</a> from the IAU at 0 January 2010, 0h TT, putting it in the hydra constellation (graphic from <a href="https://en.wikipedia.org/wiki/First_Point_of_Aries" rel="nofollow noreferrer">Wikipedia</a>) at that time:</p>
<p><a href="https://i.sstatic.net/FQ7mi.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/FQ7mi.jpg" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2021-08-26T14:55:36.160Z
Then wiki values defined in Earth's equatorial plane. Is there same values for ecliptic plane? Or how to determine Earth's equatorial plane in relation to ecliptic plane?
Aberro
CC BY-SA 4.0
2021-08-26T15:41:33.207Z
At the vernal equinox, subtract 23.44 degrees from the Declination to get the coordinates in the ecliptic plane as shown in the first plot above.
Connor Garcia
CC BY-SA 4.0
2021-08-24T16:22:00.557Z
2021-08-24T16:38:11.193Z
2021-08-24T16:38:11.193Z
Connor Garcia
<p>I can find axial tilt of planets easily, but that doesn't specify the direction of that tilt, i.e. planet's rotation axis may be anywhere in circle defined on a sphere by axial tilt value. And I can't google for obliquity direction as it only gives me obliquity value, not it's direction. Even NASA's HORIZONS only gives obliquity value. I expect there should be another angle, either from main body equinox, Earth's equinox, ascending node or maybe periapsis, that with axial tilt and orbital elements would define direction of planet's rotation axis. I know that the rotation axis  precesses, but that takes thousands of years, and compared to time from J2000 it's practically neglectable (or at least it's easier to find precession rate and make a correction for it, knowing some starting value).</p>

CC BY-SA 4.0
2021-08-24T13:37:04.557Z
See https://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies (And please don't cross-post the same question here & on Physics).
PM 2Ring
<planet><orbital-mechanics><positional-astronomy>
Where can I find planetary rotational axis direction?
Aberro
# Where can I find planetary rotational axis direction?

(Asked by: username_0 on 2021-08-24)

I can find axial tilt of planets easily, but that doesn't specify the direction of that tilt, i.e. planet's rotation axis may be anywhere in circle defined on a sphere by axial tilt value. And I can't google for obliquity direction as it only gives me obliquity value, not it's direction. Even NASA's HORIZONS only gives obliquity value. I expect there should be another angle, either from main body equinox, Earth's equinox, ascending node or maybe periapsis, that with axial tilt and orbital elements would define direction of planet's rotation axis. I know that the rotation axis precesses, but that takes thousands of years, and compared to time from J2000 it's practically neglectable (or at least it's easier to find precession rate and make a correction for it, knowing some starting value).

**Tags:** planet, orbital-mechanics, positional-astronomy

> **Comments:**
> **username_1**: See https://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies (And please don't cross-post the same question here & on Physics).  

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## 1 answers

### Answer by username_2 on 2021-08-24. Score: 2 | Accepted answer

**Answer:**

username_1 posted the answer in the above comment. The direction of each planet's rotational axis in [RA/Dec](https://en.wikipedia.org/wiki/Equatorial_coordinate_system) can be found in the table here: [en.wikipedia.org/wiki/Axial\_tilt#Solar\_System\_bodies](http://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies).

**Explanation:**

Astronomers have defined a coordinate system on the [Celestial sphere](https://en.wikipedia.org/wiki/Celestial_sphere), with z-axis coincident with Earth's North Pole, and x-axis pointed to the [First Point of Aries](https://en.wikipedia.org/wiki/First_Point_of_Aries) (aligned with the vernal equinox). Two angles define a point on the celestial sphere: right ascension and declination are analogous to longitude and latitude respectively as shown from this [wikipedia](https://en.wikipedia.org/wiki/Right_ascension) plot.

[![enter image description here](https://i.sstatic.net/MtLqn.png)](https://i.sstatic.net/MtLqn.png)

**Example:**

Uranus' North Pole direction had RA/Dec of 257.31, −15.18 degrees according to the [wikipedia table](https://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies) from the IAU at 0 January 2010, 0h TT, putting it in the hydra constellation (graphic from [Wikipedia](https://en.wikipedia.org/wiki/First_Point_of_Aries)) at that time:

[![enter image description here](https://i.sstatic.net/FQ7mi.jpg)](https://i.sstatic.net/FQ7mi.jpg)

> **Comments:**
> **username_0**: Then wiki values defined in Earth's equatorial plane. Is there same values for ecliptic plane? Or how to determine Earth's equatorial plane in relation to ecliptic plane?  
> **username_2**: At the vernal equinox, subtract 23.44 degrees from the Declination to get the coordinates in the ecliptic plane as shown in the first plot above.  

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