The Milky Way is 2.5 million light years from Andromeda and the size of the Local Group has a diameter of approxmiately 10 million light years across.
What is the distance from this Local Group to the next closest galaxy?
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2$\begingroup$ Are you asking about the nearest non-Local Group galaxy 1) from the Milky Way 2) from the geometric center of the Local Group 3) from the gravitational center of the Local Group or 4) the galaxy closest to any member of the Local Group? $\endgroup$– SchwernJan 2 at 6:16
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1 Answer
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Your question can be interpreted in many ways.
- Distance from Milky Way.
- Distance from the geometric center of the Local Group.
- Distance from the gravitational center of the Local Group
- The galaxy closest to any member of the Local Group.
Wikipedia has a list of nearby galaxies to reference, so I'll pick the first one.
One problem with answering this question is it's not entirely clear which galaxies are part of the Local Group. Another is many of our distance calculations to nearby galaxies have high error bars. Candidates include...
| Galaxy | Distance from Milky Way | Notes |
|---|---|---|
| NGC 300 | 6.07 ± 0.23 Mly | Bound to NGC 55. Probably neither part of the Local Group nor Sculptor Group. |
| NGC 55 | 6.5 ± 0.65 Mly | Bound to NGC 300. Probably neither part of the Local Group nor Sculptor Group. |
| IC 5152 | 5.87 ± 1.22 Mly | Might be part of the Local Group |
| KKR 25 | 6.37 ± 0.35 Mly | Closest to, but probably not part of, the Local Group |
The answer is about 6 million light years.
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$\begingroup$ Thank you Schwern. !Thank you for the answer that will do nicely. I was curious to learn if the distance between galaxies outside our local group is as sparse as the distance between stars. As for example if the sun were the size of a golf ball the next nearest star woud be about 750 miles away. That's a lot of scary nothing and I was just wondering if its the same story with the galaxies. $\endgroup$– SedumjoyJan 3 at 0:51
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1$\begingroup$ @Sedumjoy Measuring the distance between stars, or between galactic centers, might give you a false sense of emptiness. Solar systems and galaxies do not have sharp edges. Our Oort Cloud may (emphasis on may) extend a significant distance to Alpha Centauri; though quite sparse, it isn't empty space. $\endgroup$– SchwernJan 3 at 3:19
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$\begingroup$ Thank you I see your point it's not a simple answer is it. $\endgroup$– SedumjoyJan 3 at 14:01