Orientation of Solar System

[Turtle]

Damn Turtle, I think you've given me a brain hemorrhage.

 

I think... perhaps... just maybe... you've got your up and down backwards. Or, perhaps the astronomical community has their galactic coordinate system backwards. Or, perhaps I'm turned around... something has gotten turned around :)

 

Ok, starting over...

 

I don't think the galaxy rotates counterclockwise as viewed from the north galactic pole. I think it rotates clockwise as viewed from north. I don't think it follows the right hand rule (at least, not in the galactic coordinate system). A paper, such as this:

 

The Sun's Distance Above the Galactic Plane

 

which uses the galactic coordinate system would seem to be saying that we are above the ecliptic as is defined by that coordinate system. And I'm pretty sure, that according to that system, viewing the galaxy from the north galactic pole would show clockwise rotation.

 

-source

 

 

The above pic would have the galaxy rotating clockwise as viewed from the north. A positive latitude (above the galactic plane) would then be above the disc (as viewed from the side) where the disc is rotating left.

 

I have a suspicion of why the GCS doesn't follow the normal right hand rule. If it did then earth's north pole would point to the south side of the galaxy. In order to have earth's north and the galaxy's north roughly the same direction, the left hand rule is used. But, that's just a suspicion—I don't know if that's the reason. Nevertheless, as the pic above shows it, the galaxy does rotate clockwise as viewed from the north. It rotates in the direction of 90 deg. longitude.

 

Yes / no / maybe???

 

~modest

 

I'm afraid I still have not achieved my 'Ahah!' moment on this. :) :doh: I'm particularly vexed that none of these sources say outright the direction of rotation. It's a simple question and by damn I want a simple answer. :hihi: Your answer appears simple, but then you resort to suspicion which at the least tells me that the references so far don't make it clear to even you. :) Can we keep looking for an unambiguous source? :( If ya see a turtle on a fence-post, you know it didn't get there by itself. :)

[Turtle]

Land ho! By jove, I think I've got it! :)

 

The Milky Way Galaxy

...Considering the sense of rotation, the Galaxy, at the Sun's position, is rotating toward the direction of Right Ascension 21:12.0, Declination +48:19. This shows that it rotates "backward" in the Galactic coordinate system, i.e. the Galactic North Pole is actually a physical South Pole with respect to galactic rotation (defined by the direction of the angular momentum vector). ...

 

and

 

Curious About Astronomy: How often does the Sun pass through a spiral arm in the Milky Way?

The solar motion on top of it's circular orbit about the centre of the Galaxy (which has a period of about 230 million years) can be described by how fast it is going in three different directions

 

U = 10 km/s (radially inwards)

V = 5 km/s (in the direction of Galactic rotation)

W = 7 km/s (northwards out of the plane of the Galaxy)

 

I had a link saying about that half the galaxies rotate one way and half the other, but I lost it in the shuffle. Damn Three-card-Monte!! :) Anyway, I think I'm off that fence-post finally. .....................:)

[modest]

Excellent Turtle :)

 

And one more log on the fire:

 

Here, the galactic plane, or galactic equator, is used as reference plane. This is the great circle of the celestial sphere which best approximates the visible Milky Way. For historical reasons, the direction from us to the Galactic Center has been selected as zero point for galactic longitude l, and this was counted toward the direction of our Sun's rotational motion which is therefore at l = 90 deg. This sense of rotation, however, is opposite to the sense of rotation of our Galaxy, as can be easily checked ! Therefore, the galactic north pole, defined by the galactic coordinate system, coincides with the rotational south pole of our Galaxy, and vice versa.

 

http://seds.org/~spider/spider/ScholarX/coords.html#galactic

 

So, indeed, the galactic coordinate system is backwards (left handed as it were). Also, check out this software which is bloody brilliant:

 

Where is M13? - Home

 

You can look at Polaris (the north star) for example and see exactly where it is in the galaxy which gives a very good sense of things.

 

~modest

[freeztar]

bloody brilliant

 

+1 :)

[belovelife]

http://hypography.com/forums/astronomy-and-cosmology/17822-gravity-and-a-giant-gas-cloud.html

post 12

post 20

post 24

 

and post 9 from this thread

 

this would give a reason for the "arms" swirling in a galaxy

say you look at a galaxy with 4"arms"

this could be 4 eruptions of matter into orbit around the black hole

 

that is to say the black hole of that galaxy originally had

"hotspots" at those points, where the initial impetali process occured

then when it reached the surface of the black hole,

the impetali ->matter as we know if

 

on this i ask what is the count of these "arms"

in the galaxies we have observed

it may give us clues to the different reactions of this process

say all galaxies have 4 arms, then it would point to something

say it varyies

then each transfomation of that galaxies black hole may have

clues to the type of matter that is produces

"relation based on the crystal movment within the black hole

to x number arms produces on average

y amount heavy metals

z amount of lighter elements

to

a amount of electrons

b amount radiation

c amount of light

 

just a thought

[modest]

Land ho! By jove, I think I've got it!

 

The Milky Way Galaxy

...Considering the sense of rotation, the Galaxy, at the Sun's position, is rotating toward the direction of Right Ascension 21:12.0, Declination +48:19. This shows that it rotates "backward" in the Galactic coordinate system, i.e. the Galactic North Pole is actually a physical South Pole with respect to galactic rotation (defined by the direction of the angular momentum vector). ...

 

and

 

Curious About Astronomy: How often does the Sun pass through a spiral arm in the Milky Way?

The solar motion on top of it's circular orbit about the centre of the Galaxy (which has a period of about 230 million years) can be described by how fast it is going in three different directions

 

U = 10 km/s (radially inwards)

V = 5 km/s (in the direction of Galactic rotation)

W = 7 km/s (northwards out of the plane of the Galaxy)

 

I had a link saying about that half the galaxies rotate one way and half the other, but I lost it in the shuffle. Damn Three-card-Monte!! :eek: Anyway, I think I'm off that fence-post finally. .....................:)

 

Oh-no, I think I'm on the fence now. Does this mean we're north of the plane according to the galactic coordinate system north or the physical (rotation) north? I think I feel that hemorrhage coming again :doh:

 

~modest

[Turtle]

...

this would give a reason for the "arms" swirling in a galaxy

say you look at a galaxy with 4"arms"

this could be 4 eruptions of matter into orbit around the black hole

...

just a thought

 

that thought is on-topic over here: :eek: >> Do a spiral galaxy and a hurricane share a similar formation mechanism?

 

So, indeed, the galactic coordinate system is backwards (left handed as it were). Also, check out this software which is bloody brilliant:

 

Where is M13? - Home

 

You can look at Polaris (the north star) for example and see exactly where it is in the galaxy which gives a very good sense of things.

 

~modest

 

Looks cool! I don't own this machine however, and not allowed to download software. :doh: Any chance you could grab a screenshot of that Polaris view & post it? For that matter, any view you think would clarify the questions of our Solar Systems orientations? Dank.:)

[modest]

Looks cool! I don't own this machine however, and not allowed to download software. :eek: Any chance you could grab a screenshot of that Polaris view & post it? For that matter, any view you think would clarify the questions of our Solar Systems orientations? Dank.:lightning

 

Absolutely.

 

Polaris (the north star) doesn't show up well in a screen shot because it's pretty close to the sun (relatively speaking). You have to zoom in pretty far to look at it which looses (in a single frame) the galactic perspective. But, right next to Polaris (in the sky) is Pal 1—a globular cluster which does much better in a screen cap because it's relatively far away.

 

In this image the sun is directly left of the galactic center. It is the orange dot. The galaxy is rotating clockwise in the top image and the near part of the galaxy in the bottom image is moving to the left.

 

 

So, our (earthly) north pole is pointed roughly at Pal 1 in these images. Our south pole would be pointed in exactly the opposite direction. Our north pole is then pointed above the galactic plane (approximatly 26.5 degrees above it according to the slightly inaccurate reasoning that Polaris has a galactic latitude of 26.5).

 

Our north pole is also pointed to the outside of the galaxy (as viewed from above or below the galaxy). The galactic longitude of Polaris is 123.2 degrees, so our north pole is about 57 degrees from being pointed directly away from the galactic center.

 

I can also definitely say (because the software gives this info) that these images are oriented according to the galactic coordinate system. In other words: galactic north is pointed up in the bottom pic as defined by the GCS while the rotational (or physical) galactic north pole would be pointed down.

 

It also looks as if (and zooming in more makes it even more apparent) that the sun is slightly above the galactic ecliptic. This would mean we are above the galactic plane according to the GCS and not the other way around.

 

~modest

[Jay-qu]

Sorry I missed this conversation I could have saved you all some trouble - but you had fun searching for the answer didnt you :lightning

 

Well if anyone wants to play with the solar system/galaxy (and local group) I highly recommend downloading celestia for some real time space ship simulator fun

 

I have spent days on this program, flying around, searching, playing.. It might take you a while to get used to the controls so give it a good while and then you wont be able to put it down.

[modest]

Well if anyone wants to play with the solar system/galaxy (and local group) I highly recommend downloading celestia for some real time space ship simulator fun :eek:

 

You the man Jay-qu

 

This is one of the coolest things I've seen in a while... I thought Google earth's sky view was awesome. It's got nothing on celestia! Now I'm gonna be playing with this all night :lightning

 

~modest