Expert: Jayendra Upadhye - 2/19/2008

Question
What is the relative orientation of Earth's orbital plane to that of the Milky Way galaxy. I am trying to visualize how we must be oriented so that in winter we look out toward the edge of our galaxy, in summer toward the center near Sagittarius, and in Spring and Fall out the top or bottom of that galactic plane into intergalactic space.  Maybe this is better described by the axes of these two planes of rotation.

Answer
Hi John,
I found your interesting question in the pool.
Actually there is some talk about the sun being a captured star from another galaxy, as its orbital plane is not coplanar with the rest of the galaxy, but at a slight angle to it.

Consecquently during its 225 million year orbit round the milky way, the sun actually rises above the galactic plane and then goes below.

The axis of rotation of the sun is so oriented that the ecliptic which is at right angles to it, is itself at an angle to the galactic plane.

That is why in winters we ctually see the milky way go almost north-south and never east-west!

Though i personally believe that the small (relative to the galaxy's size) size of the original gaseous globule that became the sun, would make sure that the orientation of the sun's axis need not be perpendicular to the galactic plane at all!
Pure randomness dictated where it would point.
It ended up pointing at 60 degrees to the axis of the galaxy! making us earthlings who fly around the ecliptic, look at the milky way edge on, at a 60 deg angle!

Further, the galactic plane shows translatory motion, as our sun bobs up and down in simple harmonic motion, with respect to the galactic plane, as it orbits the galaxy.

refer:-
-------
1
http://en.wikipedia.org/wiki/Sun

2
http://en.wikipedia.org/wiki/Milky_Way

3 - http://www.badastronomy.com/bablog/2007/06/27/is-the-sun-from-another-galaxy/

A couple of paras after the picture of the intersecting galaxies, is this 60 deg thing.

please do rate the answer if you found it interesting.
regards
Jayen