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Old 09-10-2018, 08:04 PM
 
417 posts, read 129,232 times
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I can’t find an astrophysics forum for topics like

“How would an observer see an object 4 light years away in space traveling towards us at such and such a velocity

Is this the right place for that?
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Old 09-10-2018, 09:10 PM
 
Location: Westwood, MA
3,608 posts, read 4,777,981 times
Reputation: 4663
Quote:
Originally Posted by Siberiaboy View Post
I can’t find an astrophysics forum for topics like

“How would an observer see an object 4 light years away in space traveling towards us at such and such a velocity

Is this the right place for that?
City-data is unusually aggressive about competing forums, but it’s always unclear to me what counts as a competitive forum. City-data is a relocation board where old people ask where the best schools are and old people argue about the kids these days, so in my mind these are all complementary sites, not competitive:

Quora is an question site, not a bulletin board or forum, and a better place to have a specific question answered.

Physicsforums is probably a good place for homework help.

Reddit is way more active and has a specific sub forum for astrophysics.
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Old 09-11-2018, 09:04 AM
 
417 posts, read 129,232 times
Reputation: 263
Problem with Reddit it is I open an account and respond to one post someone didn’t like and got this thing called “negative karma” and ever since, that’s it for my account. With negative karma you can’t post a thing without your post being auto-rejected.
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Old 09-11-2018, 01:22 PM
 
28,638 posts, read 40,613,958 times
Reputation: 37331
Quote:
Originally Posted by jayrandom View Post
City-data is unusually aggressive about competing forums, but it’s always unclear to me what counts as a competitive forum. City-data is a relocation board where old people ask where the best schools are and old people argue about the kids these days, so in my mind these are all complementary sites, not competitive:

Quora is an question site, not a bulletin board or forum, and a better place to have a specific question answered.

Physicsforums is probably a good place for homework help.

Reddit is way more active and has a specific sub forum for astrophysics.
CD is also a forum for people who don't know who populates the forum.
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Old 09-11-2018, 01:31 PM
 
Location: Willamette Valley, Oregon
4,610 posts, read 1,337,813 times
Reputation: 6831
Well, you cast your pearls out there and hope you get more then a porkchop in return. (Ayn Rand reference)
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Old 09-11-2018, 02:00 PM
 
28,638 posts, read 40,613,958 times
Reputation: 37331
Quote:
Originally Posted by Siberiaboy View Post
I can’t find an astrophysics forum for topics like

“How would an observer see an object 4 light years away in space traveling towards us at such and such a velocity

Is this the right place for that?
Drop it in the general Science forum. You might be surprised. There are some very smart posters here.
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Old 09-11-2018, 03:44 PM
 
Location: Westwood, MA
3,608 posts, read 4,777,981 times
Reputation: 4663
Quote:
Originally Posted by Tek_Freek View Post
Drop it in the general Science forum. You might be surprised. There are some very smart posters here.
Yeah. It doesn't hurt to ask your question here or in the general science forum. There just aren't that many active users and there are some people who, to put it politely, don't agree with the scientific establishment.
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Old 09-11-2018, 05:18 PM
 
1,675 posts, read 2,563,870 times
Reputation: 1466
I can take a crack at the question.

The answer is you would see it much the same as everything else but with a possible blue shift (higher amplitude of the wavelengths over near the blue spectrum of visible light caused by the Doppler shift). How much of an amplitude increase would depend on how fast the object in question is moving toward the Earth.

Of course, at 4ly away, you would be observing the object in question as it was 4 years ago as well.
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Old 09-11-2018, 07:41 PM
 
Location: Madison, Alabama
3,971 posts, read 2,031,976 times
Reputation: 3043
Quote:
Originally Posted by jayrandom View Post
City-data is unusually aggressive about competing forums, but it’s always unclear to me what counts as a competitive forum. City-data is a relocation board where old people ask where the best schools are and old people argue about the kids these days, so in my mind these are all complementary sites, not competitive:

Quora is an question site, not a bulletin board or forum, and a better place to have a specific question answered.

Physicsforums is probably a good place for homework help.

Reddit is way more active and has a specific sub forum for astrophysics.
I interpreted his question to be, is there an Astrophysics sub-forum on city-data, not is there was an astrophysics forum out there somewhere (which I suppose would be a "competing" forum).

Given my interpretation, the answer is "no, not that I know of". The Space sub-forum is the closest one, and I believe he would find people willing to discuss the topic
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Old 09-11-2018, 08:23 PM
 
28,638 posts, read 40,613,958 times
Reputation: 37331
CD is aggressive about posters recommending other forums. They are the competition after all.
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