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Galaxies Distances

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18 years 2 months ago #23452 by dmcdona
Replied by dmcdona on topic Re: Galaxies Distances
I guess all three could have formed at the same time but have either formed in different places or have been formed in the same place and travelled in different directions.

e.g. if you and I set off from Liffey Valley and went along the M50 North and South respectively, the distance between us would increase even though we would be doing the same speed (10 km/h) :D

As far as I know, the visible universe extends to about 13.7 billion light years. But I read somewhere recently that the actual size is something like 40 billion light years - we just can't see it...

€0.02 worth from a similar non-cosmologist as Seanie

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18 years 2 months ago #23468 by disley
Replied by disley on topic Re: Galaxies Distances
more research on my part I understand the universe is expanding at or above the speed of light.If my Deep Sky galaxy and our Milky Way
are speeding apart will its image not speed towards us at the same speed?

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  • DaveGrennan
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  • IFAS Astronomer of the Year 2010
  • IFAS Astronomer of the Year 2010
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18 years 2 months ago #23472 by DaveGrennan
Replied by DaveGrennan on topic Re: Galaxies Distances

more research on my part I understand the universe is expanding at or above the speed of light.If my Deep Sky galaxy and our Milky Way
are speeding apart will its image not speed towards us at the same speed?


Disley, have you come across the balloon analogy of the universe expanding. Its often used to explain why most galaxies appear to recede from us. draw two dots on opposite sides of a balloon and blow it up so it expands at the speed of light for 6 billion years, one dot has gone 6 billion light years in one direction, the other has gone 6 billion ly in the opposite direction although that balloon has only been expanding 6 billion years, the two dots are 12 billion ly apart?

That make sense?

Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here

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18 years 2 months ago #23474 by disley
Replied by disley on topic Re: Galaxies Distances
Yes re the baloon. 2 points what about the image?

I agree re 6 billion each way but would this not mean we see the Deep

Sky galaxy as it was 6 Billion years ago and not as in the Hubble photo

not long after the big Bang ?

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18 years 2 months ago #23478 by dmcdona
Replied by dmcdona on topic Re: Galaxies Distances
My head hurts. I'm off for a lie down... :cry:

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  • DaveGrennan
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18 years 2 months ago #23485 by DaveGrennan
Replied by DaveGrennan on topic Re: Galaxies Distances

Yes re the baloon. 2 points what about the image?

I agree re 6 billion each way but would this not mean we see the Deep

Sky galaxy as it was 6 Billion years ago and not as in the Hubble photo

not long after the big Bang ?


That may be true if light could travel through the center of the balloon but it cant, space-time is curved therefore the light takes a longer time to get here. But your original question was;

why are they 12 billion light years apart?


Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here

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