General astronomy discussion

Re: Question: Orientation of Solar System to Galactic Plane

Centaur — Sun, 10 Feb 2008 01:53:13 GMT

The central region of the galaxy is in the direction of the constellation Sagittarius and not far from Scorpius. It is near them that the plane of the galaxy intersects the ecliptic (plane of Earth’s orbit) at an angle of about 60°. If the planes were nearly parallel, then we would see the Milky Way running through all of the constellations of the zodiac.

Picture a summer evening while the region between Sagittarius and Scorpius is crossing your southern meridian. The ecliptic would appear parallel to the horizon. You would observe the Milky Way sweeping upward at an angle of about 60° to the ecliptic.

You mention the Earth’s hemispheres, but they are separated by the Earth’s equatorial plane, not the ecliptic or galactic planes. The equatorial plane currently intersects the ecliptic plane at more than 23°. In the current era, the center of the galaxy is visible from the Earth’s South Pole and not the North Pole. That will eventually reverse due to precession. But in either case, observers on most of the Earth’s surface experience periods of the day during which the galactic center is above the horizon.

Re: Question: Orientation of Solar System to Galactic Plane

davidh — Sun, 10 Feb 2008 00:34:54 GMT

But that would make the central regions of the galaxy only visible from one hemisphere, likewise the outer regions would be visible only to the other hemisphere. Perhaps it is the yaw that is 60 degrees, but I would think the pitch would be fairly close to the galactic plane.

Re: Question: Orientation of Solar System to Galactic Plane

Centaur — Sun, 10 Feb 2008 00:10:51 GMT

Welcome to the discussion group, davidh.

Actually the two planes intersect at an angle of about 60°.

Question: Orientation of Solar System to Galactic Plane

davidh — Sat, 09 Feb 2008 23:52:28 GMT

A number of years ago I read somewhere that the plane of the solar system is oriented around 90 degrees to the galactic plane. That can't be right -- the geometry just doesn't work. So, how is the plane of the solar system oriented to the galactic plane?