spiral galaxies

John Russell · Post by **John Russell** » Tue Jun 13, 2006 12:28 am

In viewing galaxies on APOD, I have noticed that the galaxies turn both clockwise and counter clockwise in their spiral. Is there a specific reason for which way a galaxy is turning? Hurricanes on earth move clockwise in the northern hemisphere while in the southern they turn counter clockwise. There is however, a reason for this on earth, but what makes a galaxy go one way as opposed to another?

orin stepanek · Post by **orin stepanek** » Tue Jun 13, 2006 2:27 am

probably depends on which side of the galaxy you are viewing from. If you could see both sides of a clock dial; the backside would seem to be running counterclockwise.
Orin

Sowndbyte · Post by **Sowndbyte** » Tue Jun 13, 2006 9:14 am

good question,I have had that thought myself before. Orins answer left me a little more perplexed as it indicates that all galaxies are turning the same direction. this would indicate a universal force declaring right rotation (or left), and a mere perspective of this deciding how we view that rotation.
As I see the Galactic spin I assume that Galaxies are Tumbling and rotating in 'all' directions and that these axi' are randomly dictated and the only influence of any direction of travel is within their respective cluster and supercluster along its 'stream'. and then the oft cited interaction of galaxies occuring within this flow having influence upon the involved galaxies rotation.

orin stepanek · Post by **orin stepanek** » Tue Jun 13, 2006 12:13 pm

Think of the galaxy as a wheel. If you look at it from one side it is turning clockwise; if you look at it from the other side it will be turning counterclockwise. Try this experiment. Take a bicycle and put it upside down. Give the front wheel a spin. observe if it is going clockwise or counterclockwise. Walk around the bike and observe.
Orin

harry · Post by **harry** » Tue Jun 13, 2006 1:05 pm

Hello All

Ok,,,,,,,,,,,It seems that galaxies spin at random.

Can someone find out how many spin left and how many spin right. If the number is roughly even we could assume it is at random.

It will be interesting to prove a simple fact.

Ok ,,,,,,,,,,,,I'm going to pick on 100 galaxies

John Russell · Post by **John Russell** » Tue Jun 13, 2006 1:43 pm

I agree with the assessment that it depends on one's perspective as to which way that a galaxy is spinning, however, this does not attempt to answer the question of why it spins in a particular direction. I believe that if we could find this out then we will understand more about our universe. The reason I gave the example of hurricanes is that their spiral is not random. (I personnnally do not believe any action is random) Maybe it is dark matter that determines this rotation given it's enormity. But make no mistake....it is not random. It will be interesting to find out the outcome of the 100 galaxies as describe above...

BMAONE23 · Post by **BMAONE23** » Tue Jun 13, 2006 2:04 pm

I am of the opinion that it takes a quickly revolving supermassive black hole in the center to pull the stars around. Much like the Earth pulls the Moon around. the best proof I can think of is the fact that most moons orbit their host planets in the same direction if the planets rotation with very few exceptions.

John Russell · Post by **John Russell** » Tue Jun 13, 2006 3:50 pm

I believe that you are on to something BMAone23, however, I equate the black hole as in an analogy to a sink full of water, when the plug is pulled, the water turns either counter or clockwise in the "hole". But what makes it turn one way as oppose to the other? It is not the hole itself is it? With hurricanes it is the north and south poles that determine this. Can it be a similiar force that does this with galaxies that is not part of the galaxy itself? I have no proof, but I do believe that it is a force of which we do not see. That is why I look towards dark matter as a possible answer.

BMAONE23 · Post by **BMAONE23** » Tue Jun 13, 2006 5:02 pm

I don't know the answer with respect to galactic rotation other than to suppose that those that spin, do it in the same direction due to cosmic design. We only view them from above and below. Unfortunately, they do not rotate fast enough to determine speed and direction in the course of a single lifetime. The direction of rotation can only be descerned by examining the galactic centers and determining which direction the galactic plane the stars are orbiting in. This could take a couple of rears observation but could be done. It will be easier to determine when we get to the point that we can observe the event horizon around black holes.

As for the direction of rotation of water on the earth, I believe it is as a result of the tug of gravity on the water as it drains. Since the Earth is spherical, the higher latitudes tend to rotate at a different observed speed as the radius is smaller than at the equater. This difference causes the water, when draining, to want to spin also. If you look at the Earth from above the North Pole, It will appear to be spinning counterclockwise, and from the South Pole in a clockwise direction. This is the same direction that water drains in and hurricanes rotate in. I believe it is because gravite has a slightly different influence at latitudes farther away from the equater.

Pete · Post by **Pete** » Tue Jun 13, 2006 5:23 pm

I'd also agree with orin's statement that the direction of rotation of a galaxy simply depends on how it happens to be oriented with respect to us. Spiral Galaxy orientation certainly appears to be randomized in photos, so I'd expect a 50-50 split between cw and ccw observed rotation.

On the subject of galaxy rotation, NGC 4622 seems to be rotating in the direction opposite to what its arms would indicate:
http://antwrp.gsfc.nasa.gov/apod/ap020125.html

BMAONE23 wrote:I am of the opinion that it takes a quickly revolving supermassive black hole in the center to pull the stars around. Much like the Earth pulls the Moon around.

I could be wrong here, but Earth's rotation doesn't appreciably affect the Moon's orbit, nor does, for example, the rotation of Jupiter affect the rotation of its moons. Moons tend to orbit in the same direction as their planets because the whole system coalesced out of the same rotating cloud. If I recall correctly, spiral galaxies are also theorized to have coalesced out of slowly rotating gas clouds. Conservation of angular momentum sped up the galaxy's rotation as it contracted. Of course, the question remains as to what caused the initial rotation...

The Milky Way's central supermassive black hole is greatly outmassed by the rest of the galaxy and doesn't significantly affect it, according to this page:
http://curious.astro.cornell.edu/questi ... number=150

John Russel wrote:I personnnally do not believe any action is random

First off, welcome to the forum

Your belief is in line with Einstein's famous quote: "God does not play dice." He (Einstein, not God) believed that the universe had to be orderly and deterministic, and tried (unsuccessfully) for the rest of his life to disprove quantum theory. He theorized that actual reality was characterized by "hidden variables" that existed behind the scenes, which quantum theory incompletely described. This was proven false by John Bell, whose theorem I don't fully understand. As far as experiments have shown, particles truly do behave "randomly" on the quantum scale - it's not just humans failing to perceive patterns.

Stephen Hawking discusses randomness in a very accessible tone in the following public lecture:
http://www.hawking.org.uk/lectures/dice.html

Also: the Earth's rotation determines the rotation of hurricanes, but doesn't affect the direction in which water swirls down a drain:
http://www.loc.gov/rr/scitech/mysteries/coriolis.html
Think about it: Foucault's Pendulum rotates once a day, which is on a totally different timescale than the flush of a toilet.

Martin · Post by **Martin** » Tue Jun 13, 2006 6:25 pm

Well, actually this universe of ours is full of random occurrences. To imply that this is not the case is a fundamental error, as a result of our lack of comprehension.

As for the bike wheel analogy I think you will discover that the wheel is spinning in the same direction no matter what your perspective is.

As for “why” galaxies spin in a given direction: I believe it is simply due to the gravitational field of galaxies. The majority of the matter (over time) dictating the direction.

orin stepanek · Post by **orin stepanek** » Tue Jun 13, 2006 7:08 pm

Martin; True the wheel will be going in the same direction; but, viewed from one side it is going clockwise, and the other side [if you view it] counterclockwise. Try it!
Orin

Martin · Post by **Martin** » Tue Jun 13, 2006 7:24 pm

Does this mean that all galaxies may in fact be spinning in the same direction

BMAONE23 · Post by **BMAONE23** » Tue Jun 13, 2006 7:33 pm

Martin,

Try this:

Take a paper plate and run your finger around the underside in a clockwise direction. While maintaining the circular motion, turn the plate over and view the motion of your hand from the other side. It should be in a counter-clockwise motion

Pete · Post by **Pete** » Tue Jun 13, 2006 8:04 pm

Martin wrote:

Does this mean that all galaxies may in fact be spinning in the same direction

Yeah, around their centers.

BMAONE23 · Post by **BMAONE23** » Tue Jun 13, 2006 9:27 pm

I guess it is relative to several factors.

1) Point of view.

2) Direction of spin relative to what???
A) Planetary Magnetic North?
B) Solar Magnetic North?
C) Galactic Magnetic North?

Since our suns magnetic field experiences a flip every 11 years, does our direction of rotation flip every eleven years? When solar magnetic north points to polaris, we rotate counter-clockwise relative to magnetic north. When it flips and magnetic south points to polaris we rotate clockwise relative to magnetic north.

So the direction that a spiral galaxy rotates is relative only to the direction that its arms spiral outward. All else depends upon our point of view relative to the other galaxy.

harry · Post by **harry** » Wed Jun 14, 2006 2:59 am

Hello All

Don't you hate it that someone asks a simple question and you need to know.

Spin see link

http://curious.astro.cornell.edu/questi ... number=150

The nice thing about black holes is that although they distort space and time quite severely in their vicinity, their gravitational influence on distant objects is just as we would expect for "normal matter". How far away is "distant" for black holes? We characterize the size of a black hole in terms of its Schwarzchild Radius, or the radius within which gravity is so strong that not even light can escape. A good rule to remember is this: for a black hole of mass "M" times the mass of the Sun, its size is 3xM measured in kilometres (km). So, a solar mass black hole has a Schwarzchild Radius of about 3 km. As a rough estimate, let's say that the general relativistic effects of a black hole become insignificant at about 1000 times the Schwarzchild radius. For a solar mass black hole, then, its gravitational effects are identical to the Sun (a solar mass star) once you're about 3x1000 km = 3000 km away from it. This is a much smaller distance than that between the Earth and the Sun, for instance, and it means that if the Sun were a black hole, the Earth would not change its orbit.

http://www.aas.org/publications/baas/v3 ... 99/374.htm

NGC 4622 is a nearly face-on spiral with an intriguing morphology. Byrd et al (1989) pointed out that besides a pair of outer arms winding outward clockwise (CW), NGC4622 has a weaker, single inner arm winding outward counter clockwise (CCW). Byrd et al noted that one set of arms must be leading, a very rare configuration. Buta, Crocker, and Byrd (1992) showed using BVI photometry that the single inner arm is a stellar dynamical feature, not an unusual dust distribution. NGC 4622 was thus the most convincing case of a galaxy having leading spiral structure. However, which set of arms is leading? Based on theory and numerical simulations, Byrd, Freeman, and Howard (1993) suggested that the inner arm leads

Sowndbyte · Post by **Sowndbyte** » Wed Jun 14, 2006 5:40 pm

as I considered the analogies offered to explain the rotation theory and point of perspective I grasped what I was missing from the point, It would be simpler stated as,
'If you see a galaxy spinning right you are looking at its North pole,if it is turning left you are looking at it's south pole'
But that openend up even more questions
which direction are these spinning? or are they elliptical because they have an opposite spin?
nice discourse folks.http://antwrp.gsfc.nasa.gov/apod/ap060520.html

John Russell · Post by **John Russell** » Wed Jun 14, 2006 6:42 pm

I apologize to everyone for my clarity in this topic. I will try to get my point across better this time. I am not concerned in whether or not the galaxies spin north or south, clockwise or not. My point is that with hurricanes they turn clockwise or counter clockwise because of the poles of the EARTH. Aside from the galaxies spin direction, can it be that the universe has "poles" that make the galaxies spin(regardless of direction?)What are your thoughts? Something must make them spin.

Pete · Post by **Pete** » Wed Jun 14, 2006 9:36 pm

Sowndbyte: you linked to M87, an elliptical galaxy. Stars in elliptical galaxies follow random orbits which don't add up to any bulk rotation pattern. To quote this random but informative page, "star orbits [in elliptical galaxies] are aligned in a wide range of angles and have a wide range of eccentricities."

John Russel: I believe spiral galaxy rotation is supposed to have arisen from relatively minor inhomogeneities in the early Universe. (OK, but what caused those?) Regarding whether the Universe has "poles" (of rotation): For what it's worth, I'd say the Universe is not rotating based on the isotropy of the Cosmic Microwave Background. A rotating Universe also apparently gives rise to the possibility of time travel, which I'm not touching with a ten-light-nanosecond pole. This person did his PhD research on the possibility that the Universe is rotating:
http://www.ettnet.se/~egils/essay/essay.html

harry · Post by **harry** » Thu Jun 15, 2006 5:13 am

hello All

The question is

Is their someform of gravitational control or conformity, or something like that.

As for the universe spinning.

No Way.

Why?

Because the word UNIVERSE means all, and ALL cannot spin if its infinite.

But! The parts within the universe do spin, because they are part of the never ending story and are affevted by the gravity matrix.

Galactic Groove · Post by **Galactic Groove** » Fri Jun 16, 2006 3:20 pm

harry wrote:Can someone find out how many spin left and how many spin right. If the number is roughly even we could assume it is at random.
...
Ok ,,,,,,,,,,,,I'm going to pick on 100 galaxies

It wouldn't matter. Let's assume that by chance all 100 galaxies you chose happened to spin clockwise from our position here on Earth. What about the some alien race that lived on the opposite side viewing all the same galaxies? They would see them all spinning counter-clockwise, much like the bicycle wheel example mentioned already. I think the true fact here is that you can't label it as spinning in a specific direction simply because it's a biased observation.

harry · Post by **harry** » Sat Jun 17, 2006 12:28 am

Hello GG

Yes you are right.

But! we need to know if there is a pattern or is it random.

If we have the answer, it solves the problem.

harry · Post by **harry** » Sat Jun 17, 2006 12:54 am

Hello all

OK

Three Galaxies in Draco
http://antwrp.gsfc.nasa.gov/apod/ap060506.html

From left to right are face-on spiral NGC 5985, elliptical galaxy NGC 5982, and edge-on spiral NGC 5981 ,,,,,,,
these galaxies all do lie roughly 100 million light-years from planet Earth

Visitors' Galaxy Gallery

http://antwrp.gsfc.nasa.gov/apod/ap050618.html

4 out 6 c-clockwise

Spiral Galaxies in Collision

http://antwrp.gsfc.nasa.gov/apod/ap041121.html
two stars colliding one clockwise and one c-clockwise

Looking through many galaxies,,,,,,,I think they spin at random

randall cameron · Post by **randall cameron** » Sat Jun 17, 2006 9:32 am

I guess that the rotation of any particular system is random. Note that individual galactic planes and apparent rotation appear random even in relation to the overall rotation of the groups to which they belong.

In every treatise I have read on the standard model (almost unrecognizable now), or galaxy, star, or planet formation, structures are believed to form simply because of very small irregularities (clumpiness?) in the goo from which they formed.

Similarly, the rotation (everything in space spins in some direction or other) is due to the fact that any random clump of primordial space gas, whether a proto-galaxy, proto-star cluster, proto-star or proto-planet is going to have some small net angular momentum in some direction (absolutely zero angular momentum would border on the miraculous). As things contract, spin rate increases, like the ice skater pulling in her arms.

Look at our solar system -- the overwhelming majority of the mass is in the sun, which spins quite fast because it is so small in relation to the original barely moving gas cloud. The overwhelming majority of non-sun mass also spins in the same direction. Venus (rotationally coupled to Earth?) and Uranus (result of a massive impact?) and Neptune's moon Triton (captured Kuiper object?) are mysterious exceptions. Only out in the Oort cloud is motion believed or guessed to be more random, based on the relatively random trajectories of non-periodic comets.

As these systems accrete or coalesce, the prevailing net angular momentum imparts spin and orbital rotation overwhelmingly about the original net axis of rotation, because particles or objects rotating either "across the grain" or highly eliptically have a much higher probability of collision and accretion, or orbital capture.

The relative rotation direction or axis of non-coupled systems would be presumably random.

As to what is the "north" pole of a galaxy, this is arbitrary. The only sense in which a galaxy might have absolute right- or left-hand rotation is in relation to the direction of its spiral arms.

Starship Asterisk*

spiral galaxies

spiral galaxies

unanswered

Galactic poles