Ecliptic Plane's relation to Galactic Plane

Nov26-03, 01:01 PM

Hi,

What is the orientation of the ecliptic plane of our solar system in relation to the plane of the galaxy?

One source I found said they were aligned to within 5.5 degrees. http://www.earthsky.com/2000/es000304.html

Another source I found stated that the orbital planes were 63 degrees apart. http://www.essex1.com/people/stauffer/MLS/solarsys.html

Does anyone know for sure?

Also, are all of the orbital parameters of our solar system around the galactic core known?

Thanks,
Glenn

**Labguy** · Nov26-03, 02:50 PM

Originally posted by Glenn
Hi,

What is the orientation of the ecliptic plane of our solar system in relation to the plane of the galaxy?

One source I found said they were aligned to within 5.5 degrees. http://www.earthsky.com/2000/es000304.html

Another source I found stated that the orbital planes were 63 degrees apart. http://www.essex1.com/people/stauffer/MLS/solarsys.html

Does anyone know for sure?

Also, are all of the orbital parameters of our solar system around the galactic core known?

Thanks,
Glenn

The nearest bright star to the North Galactic Pole is Arcturus, in the constellation Bootes. I haven't made a measurement, but this is far more than 5.5 degrees; sounds like the 63 degrees is about right.

http://www.site.uottawa.ca:4321/astr...inatecomponent says:

"North galactic pole is a part of Coma Berenices
has galactic latitude 90 degrees
is opposite of south galactic pole
has acronym NGP
has definition A point in the constellation Coma Berenices where we look perpendicular to and above the Galactic Plane. The nearest bright star to the North Galactic Pole is Arcturus, in the neighboring constellation Bootes."

Labguy

**chroot** · Nov26-03, 03:18 PM

From your first link:

Astronomical theories predict that the plane of the solar system should lie in the plane of the galaxy. And it does. The solar system is tipped by only about 5.5 degrees out of the galactic plane.

I don't know who these guys are, but I don't think either of those statements is correct.

- Warren

**Nereid** · Nov27-03, 12:26 AM

Here are two short pages with explanations and formulae:
http://www.ess.sunysb.edu/fwalter/PHY515/coords.html
http://scienceworld.wolfram.com/astr...ordinates.html

An all-sky summary of the IRAS (infrared astronomy satellite) observations:
http://coolcosmos.ipac.caltech.edu/i...AS/allsky.html
This is an Aitoff projection, in galactic coordinates. See the blue band running across the middle, at an angle of ~60^o? That's the ecliptic plane, blue because the fine particles which lie in the ecliptic plane (and give us the zodiacal light) are hot compared with the dust etc which gives rise to the galactic emission.

Also, are all of the orbital parameters of our solar system around the galactic core known?

I'm not sure what you're asking Glenn. We know the distance to the galactic centre, the distance above the mid-plane of the disk, the time it takes to make one revolution, ... the eccentricity isn't well known though.

Nov28-03, 09:16 AM

Originally posted by Nereid

I'm not sure what you're asking Glenn. We know the distance to the galactic centre, the distance above the mid-plane of the disk, the time it takes to make one revolution, ... the eccentricity isn't well known though.

Do we know the inclination? Is there an inclination or does our solar system maintain a fixed distance above the mid-plane of the galactic disk?

Basically I am asking if the solar system actually "orbits" the center of the galaxy?

Thanks,
Glenn

**Nereid** · Nov28-03, 02:03 PM

Originally posted by Glenn
Do we know the inclination? Is there an inclination or does our solar system maintain a fixed distance above the mid-plane of the galactic disk?

Basically I am asking if the solar system actually "orbits" the center of the galaxy?

AFAIK, the motion isn't a simple ellipse.

For example, there is a 'vertical' oscillation, about the mid-plane of the disk. I don't remember what the period of this oscillation is, but it's unlikely to be a simple fraction of the rotation period. The amplitude is modest, only a few tens of parsecs, IIRC.

Then there are encounters with giant molecular clouds, which don't necessarily orbit the centre of the galaxy in the same way the Sun does.

Lately nearby galaxies in the process of being canabalised by the Milky Way have been discovered (Saggitarius, Carina); the extent to which they affect the orbit of the Sun is, as yet, unknown.

**Labguy** · Nov28-03, 02:24 PM

Originally posted by Nereid
AFAIK, the motion isn't a simple ellipse.

For example, there is a 'vertical' oscillation, about the mid-plane of the disk. I don't remember what the period of this oscillation is, but it's unlikely to be a simple fraction of the rotation period. The amplitude is modest, only a few tens of parsecs, IIRC.

Then there are encounters with giant molecular clouds, which don't necessarily orbit the centre of the galaxy in the same way the Sun does.

Lately nearby galaxies in the process of being canabalised by the Milky Way have been discovered (Saggitarius, Carina); the extent to which they affect the orbit of the Sun is, as yet, unknown.

There are a bunch of interactions (pertubations) as you say, but most sites quote a 225 to 250 million year "orbit" for our solar system around the galaxy. That's a long time, but still very short on the time scale of galactic collisions.

http://www.chron.com/content/interac...ds/990602.html
states 226 million years.

Labguy