Talk:Axial tilt
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I have a question about the Moon's 1.5 degree axial tilt. If astronomers were to give the Moon northern and southern tropical circles, and the equivalent of arctic and antarctic circles, would the tropics be 1.5 degrees north and south of the Moon's equator, and the arctic and antarctic circles 88.5 degrees north and south of the Moon's equator?
Thank you. Bruce McClure
Wrong passage
I took out the sentence which said that for "the axial tilt is 0 or 180 depending on whether the planet is rotating in the same direction as its orbital motion". This does not make any sense for the following two reasons:
- The axial tilt is the angle between the normal of the orbital plane and the axis of rotation of the body. So if the rotation axis is perpendicular to the orbital plane then the angle is 90 degrees, not more, not less! The axial tilt of Uranus is listed as 97 degress.
- If the planet's axis of rotation actually lies in the orbital plane how do you define if it has proper or retrograde rotation? The rotation direction is determimed by the rotation of the "north pole" with respect to the ecliptic but in that case both poles actually lie on the orbital plane and neither one is to the north.
Smartech 03:41, 6 May 2005 (UTC)