Quizzes & Puzzles14 mins ago
Expanding Universe
If the universe is expanding , is anyone / institution , constantly updating the information as to the distances between planets /stars / galaxies ?
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No best answer has yet been selected by Bazile. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.Not really any need locally, at least -- the expansion rate is only visible over superlarge scales. Most galaxies nearby are moving closer to us, if anything.
Over the larger scales, meanwhile, I don't think the measurements are quite accurate enough to justify constant updates. On the other hand, the relevant parameter, the Hubble Constant, probably is meaning remeasured fairly regularly, especially over the last 20 years.
Over the larger scales, meanwhile, I don't think the measurements are quite accurate enough to justify constant updates. On the other hand, the relevant parameter, the Hubble Constant, probably is meaning remeasured fairly regularly, especially over the last 20 years.
You'll have to start by defining 'distance'. It's not quite as easy as you might think!
http:// curious .astro. cornell .edu/ab out-us/ 104-the -univer se/cosm ology-a nd-the- big-ban g/expan sion-of -the-un iverse/ 619-how -do-we- define- distanc e-in-an -expand ing-uni verse-i ntermed iate
Once you've decided on what you mean by 'distance' though, some fairly basic mathematics is all that's needed to keep track of things. (e.g. if I know that a snail that's currently 10m from me is moving away at 1m per hour then in 5 hours time I'll know that it's 15m away. I won't need to get a tape measure out, I can simply calculate the answer I require).
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Once you've decided on what you mean by 'distance' though, some fairly basic mathematics is all that's needed to keep track of things. (e.g. if I know that a snail that's currently 10m from me is moving away at 1m per hour then in 5 hours time I'll know that it's 15m away. I won't need to get a tape measure out, I can simply calculate the answer I require).
Yes Buenchico .
But i dont want to do any calculations
If i open a text book written today it will say A is x amount of light years away from B
In for example 10 years time that info in the text book will be out of date .
So i want that text book updated or another text book written with the ' current ' information
But i dont want to do any calculations
If i open a text book written today it will say A is x amount of light years away from B
In for example 10 years time that info in the text book will be out of date .
So i want that text book updated or another text book written with the ' current ' information
Theland
Jim - Some galaxies moving closer?
I thought ALL galaxies showed red shift?
New to me. 17:05 Tue 15th Jan 2019
In addition to galaxies moving with space (due to expansion) galaxies also move through space. The Andromeda galaxy (a relative neighbour) is moving towards us and will eventually collide or merge with our galaxy (the Milky Way), easily overtaking the expansion rate given the relatively short time and distance involved.
Jim - Some galaxies moving closer?
I thought ALL galaxies showed red shift?
New to me. 17:05 Tue 15th Jan 2019
In addition to galaxies moving with space (due to expansion) galaxies also move through space. The Andromeda galaxy (a relative neighbour) is moving towards us and will eventually collide or merge with our galaxy (the Milky Way), easily overtaking the expansion rate given the relatively short time and distance involved.
There's so much gap between matter and so little matter, you'd probably not notice the merge were you there.
(Unsure if dark matter changes that.)
I believe the local motion is 'true' motion so can be either away from or towards; whereas expansion on larger scales is more likely to be apparent from space being created between the two 'objects'.
(Unsure if dark matter changes that.)
I believe the local motion is 'true' motion so can be either away from or towards; whereas expansion on larger scales is more likely to be apparent from space being created between the two 'objects'.