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We Finally Know How Big the Milky Way Is: 1.9 Million Light-Years in Diameter

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#1 ILikePluto

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Posted 23 March 2020 - 08:47 AM

We finally know how big the Milky Way is:  a whopping 1.9 ± 0.4 million light-years in diameter:

 

Science News:  Astronomers have found the edge of the Milky Way by Ken Croswell



#2 B l a k S t a r

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Posted 23 March 2020 - 09:06 AM

Gravitational influence does not equal physical size. By the definition in the article the MW & Andromeda are practically kissing. 


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#3 sg6

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Posted 23 March 2020 - 09:07 AM

One problem I tend to see on these is that the next person to measure the size almost has to get a different result.

Otherwise it is a case of:

I got the same answer as Mike did 2 years ago, suppose I needn't have bothered.

 

So the next measurement in many ways has to be different.



#4 happylimpet

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Posted 23 March 2020 - 10:06 AM

Gravitational influence does not equal physical size. By the definition in the article the MW & Andromeda are practically kissing. 

That ws my first thought - I assumed they wer etalking about the 'Hill Sphere' or similar (where an object's gravity dominates) but it seems this is the physical size to the edge of our dark matter halo - though not written that clearly - so is a true size of our galaxy.


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