Difference between axial tilt and inclination

In summary, axial tilt is the angle of a planet's rotational axis with respect to its orbital plane, while inclination is the angle of its orbital plane with respect to the solar rotational axis. The most common measurement for inclination is relative to the ecliptic, or the plane of the Earth's own orbit. The invarible plane is the average plane through which all planets orbit, weighted by angular momentum. The Line of Nodes is the point where the path of the planet's orbit intersects the ecliptic and is used as a reference point for orbital calculations.
  • #1
Philosophaie
462
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What is the difference between axial tilt and inclination? I know that axial tilt is the angle between the perpendicular to the elliptical plane and the north pole with the right time of year facing the sun. I guess the Inclination to the Sun's Equator is self explanatory. The other two I have no idea even after reading their Wiki articles. Could someone please explain?

axial tilt(Earth)= 23.49693deg @2000 epoch
inclination to the elliptic(Earth) = N/A
Inclination to the Sun's Equator(Earth) = 7.155deg
Inclination to the Invariable Plane(Earth) = 1.57deg
 
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  • #2
Axial tilt is the angle of the planetary rotational axis relative to its orbital plane around the sun. Inclination is the angle of its orbital plane relative to the solar rotational axis.
 
  • #3
In astronomy, the most common measurement for inclination of planets is relative to the ecliptic or the plane of the Earth's own orbit.

Of course this gives a zero (or Not Applicable) value for the Earth's own inclination. However sometimes you will see a small non-zero value given. This value is relative to the inclination at some particular reference date (like the vernal equinox for the Julian year 2000).

The invarible plane is the average plane through which all the planets orbit, weighted by angular momentum. If you average out the angular momentum of the Solar system (ignoring the Sun). you get a plane through which you can say the system rotate in. This is the invarible plane.
 
  • #4
The Inclination based on the elliptic is the angle between the line between the (Earth's center of mass and Sun's center of mass) and the Sun's axis of rotation. The data enclosed says that Earth is N/A. Why?

Does not the Inclination change or at least the angle changes due to the fixed nature of the tilt dynamics of the planets and the sun. The axial tilt does not change except it's orientation towards the sun.
 

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  • #5
Now we are forgetting the whole Barycenter concept. I think the plane of the axial tilt is still going to be the same no matter where the center of mass is, within a few hundreth of a degree. The axial tilt produces the same seasons year round as the Earth travels around the Sun. The Inclination is the angle the elliptic makes with planes of the Sun.
 
  • #6
Philosophaie said:
The Inclination based on the elliptic is the angle between the line between the (Earth's center of mass and Sun's center of mass) and the Sun's axis of rotation. The data enclosed says that Earth is N/A. Why?

The ecliptic is the plane of the Earth's orbit and has nothing to do with the Sun's axis of rotation unlike the inclination based on the Sun's equator which does.

It is N/A because it is meaningless to talk about the tilt of the Earth's orbit wth respect to the Earth's orbit.
 
  • #7
The Line of Nodes is the point where the path of the plane of the planet and the moon intersect. The sun and its planets also base their orbital calculations on the Longitude of the Ascending Node and this Line of Nodes. The ancients based their observations on the Cusp of the Constellation Aries (or in Pisces now) at the equatorial center of the sky during the Vernal Equinox. This point is where the Longitude of the Ascending Node from is most calculation of Ellipses and most other orbital calculations are based. Where is this plane come into play in the calculations of the axial tilt and inclination?
 
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  • #8
Philosophaie said:
The Line of Nodes is the point where the path of the plane of the planet and the moon intersect. The sun and its planets also base their orbital calculations on the Longitude of the Ascending Node and this Line of Nodes. The ancients based their observations on the Cusp of the Constellation Aries (or in Pisces now) at the equatorial center of the sky during the Vernal Equinox. This point is where the Longitude of the Ascending Node from is most calculation of Ellipses and most other orbital calculations. Where is this plane come into play in the calculations of the axial tilt and inclination?


For moons orbiting planets, the inclination is measured with respect to the planet's equator. However, for planet's orbiting the Sun the most common and most convenient reference is the ecliptic, or the plane of the Earth's own orbit. In this case, the Line of Nodes is the path where the plane of the planet of interest's orbit intersects the plane of the Earth's orbit. The position of the ascending and descending nodes are measured from the position of the Vernal Equinox.

Axial tilt is measured with respect to the planet's own orbit. Thus Jupiter has an inclination of 1.31° with respect to the Earth's orbit, and an axial tilt of 3.13° with respect to a line perpendicular to its own orbit.
 

1. What is axial tilt?

Axial tilt is the angle at which a planet's axis of rotation is tilted in relation to its orbital plane around the sun. This tilt is responsible for the changing seasons on Earth.

2. What is inclination?

Inclination refers to the angle at which a planet's orbital plane is tilted in relation to the ecliptic plane, which is the plane of Earth's orbit around the sun. This angle can vary for different planets.

3. What is the difference between axial tilt and inclination?

The main difference between axial tilt and inclination is the axis around which the angle is measured. Axial tilt is measured in relation to the planet's own axis of rotation, while inclination is measured in relation to the ecliptic plane.

4. How do axial tilt and inclination affect a planet?

Axial tilt and inclination both play a significant role in determining the climate and seasons on a planet. The greater the tilt or inclination, the more extreme the seasonal changes will be. Inclination also affects a planet's orbital path and can influence its gravitational interactions with other objects in the solar system.

5. Can axial tilt and inclination change over time?

Yes, both axial tilt and inclination can change over time due to a variety of factors such as gravitational interactions with other planets or objects, and the redistribution of mass within a planet. These changes can have significant impacts on a planet's climate and orbital path.

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