~41,000 years, caused by changes in tilt of the earth relative to the plane of the orbit.
Obliquity - book - was created on 2010-03-25.
Uranus with an obliquity of 98oThe dwarf planet Pluto has an obliquity of 120oSee related link for a pictorial.
obliquity
The obliquity.
Uranus has an obliquity (axial tilt) of 97.77 degrees.
The Earth's tilt, or inclination, or obliquity is about 23.44 degrees from the plane of its orbit around the Sun.
If by parallel you mean that the axis points in the same direction throughout the year, the answer is yes.
Oblique has 2 meanings :- 1- Having a slanting or sloping direction, course, or position. 2- Devious, misleading, or dishonest
Obliquityis away of describing aplanet's axial "tilt". The answer is Uranus or Venus, depending on the way the planet's north pole is defined.
It rotates in the "retrograde" direction. "Obliquity" is another way of talking about the tilt of a planet's axis. You might say the planet is "upside down". The direction of the rotation is called "retrograde" ("backwards" compared with the Earth's rotation). Note: there is a complication here about how astronomers define the North pole of a planet, but that's probably an unnecessary complication for most people.
In astronomy it is called the axial tilt (also called obliquity) and sometimes just called the imaginary axis.
All planets have some degree of axial tilt - or obliquity. Mercury has the smallest with a tilt of only 0.027 degrees - so small as to be nearly zero.