Four arms or two?

[Ann]

Four-armed goddess Lakshmi. Image credit: Linda Kennard

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Astronomers used to believe that the Milky Way has four arms.

Phys.org wrote:

The case for a four-armed Milky Way may have just gotten stronger.

A team of Brazilian astronomers used star clusters embedded in their natal clouds to trace the galaxy's structure. "Our results favour a four-armed spiral galaxy, which includes the Sagittarius-Carina, Perseus, and outer arms," remarked the group from the Universidade Federal do Rio Grande do Sul.

A four-armed Milky Way would look something like this.

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A four-armed Milky Way may be somewhat similar to UGC 12158. ESA/Hubble & NASA.

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However...

Phys.org wrote:

For many years, space scientists have imagined the Milky Way galaxy as a spiral shape with a central bulge and four main spiraling arms—with several other smaller branching arms. Over the past several years, telescope technology has improved and along with it, the realization that the vast majority of galaxies conform to just one of three main shapes: spiral, irregular and elliptical. Also, most have two main arms with spirals splitting into smaller arms.
...
Such observations suggest that if the Milky Way is a spiral galaxy with four arms, it would be extraordinarily rare. And if that were the case, there would have to be some unique attributes that would have led to such a unique shape. The researchers with this new effort suggest it is more likely that we got the shape wrong from the start. They believe that, like most other galaxies, the Milky Way has just two main arms.

So statistics argues that the Milky Way has only two main two arms and not four!

Two arms. Not four.

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The Milky Way most likely has only two main arms. Credit: NASA.gov.

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Ann

[Rauf]

Four-armed goddess Lakshmi. Image credit: Linda Kennard

---

Astronomers used to believe that the Milky Way has four arms.

Phys.org wrote:

The case for a four-armed Milky Way may have just gotten stronger.

A team of Brazilian astronomers used star clusters embedded in their natal clouds to trace the galaxy's structure. "Our results favour a four-armed spiral galaxy, which includes the Sagittarius-Carina, Perseus, and outer arms," remarked the group from the Universidade Federal do Rio Grande do Sul.

A four-armed Milky Way would look something like this.

---

A four-armed Milky Way may be somewhat similar to UGC 12158. ESA/Hubble & NASA.

---

However...

Phys.org wrote:

For many years, space scientists have imagined the Milky Way galaxy as a spiral shape with a central bulge and four main spiraling arms—with several other smaller branching arms. Over the past several years, telescope technology has improved and along with it, the realization that the vast majority of galaxies conform to just one of three main shapes: spiral, irregular and elliptical. Also, most have two main arms with spirals splitting into smaller arms.
...
Such observations suggest that if the Milky Way is a spiral galaxy with four arms, it would be extraordinarily rare. And if that were the case, there would have to be some unique attributes that would have led to such a unique shape. The researchers with this new effort suggest it is more likely that we got the shape wrong from the start. They believe that, like most other galaxies, the Milky Way has just two main arms.

So statistics argues that the Milky Way has only two main two arms and not four!

Two arms. Not four.

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The Milky Way most likely has only two main arms. Credit: NASA.gov.

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Ann

Well, time to ask our alien friends in LMC and SMC about how our galaxy looks like

[Ann]

Well, time to ask our alien friends in LMC and SMC about how our galaxy looks like

Alien on Oumuamua from SMC.png

https://en.wikipedia.org/wiki/ʻOumuamua

Ann

[Rauf]

Well, time to ask our alien friends in LMC and SMC about how our galaxy looks like

Alien on Oumuamua from SMC.png


https://en.wikipedia.org/wiki/ʻOumuamua

Ann

I used a software called SpaceEngine to see how big Milky Way looks like from a hypothesized planet on the LMC.. They have a great night sky out there!