About Axis of Earths Rotation?

Question

1. Does the Axis of earth makes a fixed angel with the Orbit (around the Sun) or the angel changes with the postion on the Eliptical Orbit.I mean , whether the axis postion is parellel thru out the orbit or not ?
2. Is Equator parallel to the Orbit of the earth or it makes equal angel as the Axis makes with the Orbital path ?
3.Is the Orbit around Sun perfectly Eliptical and symetric ?
4.If yes, why dont' we experiance 2 Summers and 2 winters ?

5.Is the distance of earth from Sun is same On every Equinox ?

6.There are number of websites offering Animation of Earths Rotation and Revolution explaining the Day and Night at the Poles.
In your opinion, Which web site shows most easy to understand Animation amongst these ?

Answer 1

1. The direction of the earth's axis is *relatively* constant throughout the year. But it does (very slowly) rotate, taking about 27000 years to make a complete rotation. This motion is called "precession of the equinoxes.
2. The equator is tilted from the plane of the ecliptic by about 23.4°, which is called the "obliquity" of the axis. The obliquity also changes slowly with time, and is currently decreasing a bit. 2000 years ago, it was about 23.7°.
3. The orbit of earth around the Sun is an ellipse, but it is not a perfect ellipse, due to small perterbations of the Moon and other planets.
4. The ellipticity of Earth's orbit also changes, and at the current time it is fairly low -- meaning that the orbit is almost (but not quite) circular. For that reason, the ellipticity of the orbit plays only a minor role in the seasons: making winter shorter in the northern hemisphere, and longer in the southern hemisphere.
5. The distance between Earth and the Sun is nearly the same from one equinox to the next, but not quite. The position of perihelion (closest point to the sun) also slowly changes over time. Currently perihelion occurs in the first week in January. But 2000 years ago, it was in late autumn.
6. I'll take a pass on that one :-)

Answer 2

1) Yes, it is constant through the year, but the axis does precess over a very long period (like 25000 years or so)

2)The equator is fixed with respect to the axis, so it makes an angle.

3) I'm sure that disturbing forces from other planets throw it off a bit, but it's pretty darn close

4) We do--in 2 years. Remember the seasons are a function of the axis angle with respect to the sun, not the orbital position.

5) It can be different between fall and spring. And the orbit precesses very slightly from year to year. Very slightly.

6) Go found your own.

Answer 3

Hi. Good questions. 1) The angle appears fixed at about 23.6 degrees to its orbit plane, but this may change over long time periods. 2) The equator is at an angle. The tropical circles are at the same angular distance from the equator (23.6 or so) is the same as the arctic and antarctic circles are (also 23.6 or so). 3) ALL orbits are elliptical with two foci. Not sure what you mean by 'perfectly'. 4) Because only one focus has the Sun. 5) Not necessarily. The distance has little to do with the seasons. 6) "Ya pays ya money and ya takes ya choice"

Answer 4

Happy Homework!