Do All Spiral Galaxies Rotate in the Same Direction from Earth's Perspective?

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Discussion Overview

The discussion centers around the rotation direction of spiral galaxies as observed from Earth, questioning whether all spiral galaxies rotate in the same direction and how this relates to cosmic principles and black hole characteristics. The scope includes theoretical considerations, observational perspectives, and implications of cosmological principles.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants propose that the rotation direction of spiral galaxies is dependent on the observer's vantage point, suggesting that there is no uniform direction from Earth's perspective.
  • One participant notes that if all spiral galaxies rotated in the same direction, it would contradict the cosmological principle, implying a violation of isotropy in the universe.
  • Another participant raises a question about whether spiral galaxies can have a "top" and "bottom" based on the orientation of their supermassive black holes, and whether their rotation is influenced by the black hole's rotation.
  • Responses clarify that black holes do not have defined "tops" or "bottoms" and that they are spherically symmetric, which complicates the notion of directional rotation.
  • It is suggested that while the material in a galaxy may coalesce in a common rotational direction, external events like galaxy collisions could lead to varied rotational dynamics.
  • Some participants express uncertainty about the effects of cosmic events on the rotation of spiral galaxies and the overall understanding of galaxy formation.

Areas of Agreement / Disagreement

Participants generally do not agree on whether all spiral galaxies rotate in the same direction, with multiple competing views presented regarding the influence of vantage point, cosmic principles, and black hole characteristics.

Contextual Notes

The discussion highlights limitations in understanding galaxy formation and dynamics, particularly regarding the effects of collisions and the nature of black holes, which remain unresolved.

JBash
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Obivously, the direction of the rotation of a Spiral Galaxy depends on the vantage point from which you look at it. From Earth, do all Spiral Galaxies rotate in the same direction? Or, because the universe is so vast, the rotation direction is irrelevant and has morre to do with prior collisions?
 
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I'm not aware of any preferred rotational direction, or axial inclination of spiral galaxies.
 
JBash said:
Obivously, the direction of the rotation of a Spiral Galaxy depends on the vantage point from which you look at it. From Earth, do all Spiral Galaxies rotate in the same direction?

No.

JBash said:
Or, because the universe is so vast, the rotation direction is irrelevant and has morre to do with prior collisions?

Yes.
 
JBash said:
From Earth, do all Spiral Galaxies rotate in the same direction?

If they did, it would be a very serious violation of the cosmological principle (the universe would be heavily anisotropic) and you'd hear about it.
 
Thank You Chronos, K-86 and Space Tiger but...

This leads me to a more focused and possibly silly question...
Can a Spiral galaxy have a Top and a bottom- Top being the face of the super massive black hole'e opening meaning the bottom is the opposite side?

If so, do sprials rotate based on their supermassive bh's rotation and do they all rotate in the same direction?
 
JBash said:
This leads me to a more focused and possibly silly question...
Can a Spiral galaxy have a Top and a bottom- Top being the face of the super massive black hole'e opening meaning the bottom is the opposite side?

Black holes don't have tops or bottoms. Remember, black holes are matter that have been compressed to a radius at which the escape velocity is greater than the speed of light. The use of the word "hole" in the name is misleading.
 
(Non-rotating) black holes are spherically symmetric; they appear the same in every direction. As Markjdb said, they don't have "tops" or "bottoms" or "openings." Anything can fall into a black hole from any direction. They're spheres.

And no, there is no preferred direction from which to view a spiral galaxy. They'd look pretty much the same from either side.

Since the entire galaxy coalesced out of a large cloud of gas, you'd expect that all rotations within the galaxy would be in the same direction -- the black hole would rotate in the same direction as the material which has fallen into it and "donated" its angular momentum -- but catastrophic events like galaxy collisions and mergers can probably create more unusual situations.

Galaxy formation is not entirely understood yet, but (if I recall correctly) spirals are thought to not have undergone collisions or other interactions. Spirals are relatively "undisturbed," while lenticular and irregular galaxies are left in the aftermath of an interaction.

- Warren
 

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