I just came across this post, whose first link is to here, which is actually broken and goes to a totally wrong post on a wrong site. I noticed that the Linked section on the right contains the correct link to this post. I guess what happened is that the link in the question pointed to the original location of the linked post, but it was subsequently migrated from Astronomy SE to Physics SE, and the link in the Linked section was updated correctly but the link in the post was not. Why is that so? Is there a bug in the SE software?

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    $\begingroup$ Note to readers: I went ahead and fixed the link; the broken link is in revision 7. The question about the bug is still interesting. $\endgroup$
    – rob Mod
    Feb 15, 2017 at 6:14
  • $\begingroup$ I know a similar issue came up once before. I participated in the discussion. But A search doesn't seem to find it. $\endgroup$ Feb 15, 2017 at 19:04

1 Answer 1


Educated guess: I think the answer here is that the current Astronomy.SE is the second iteration of that site. The first iteration failed at some stage in the Area51 process and Physics absorbed many of their questions. Later, apparently, a second Astronomy site was begun. I suppose it's possible that some post IDs got re-used.

Note that the correct link, to physics.stackexchange.com/q/26461, is to a question, while the link in the text, which redirects to astronomy.stackexchange.com/a/1211, is to an answer. When the new astronomy site accumulated enough new content that the post ID got re-used, then the link went from "just broken" to being broken in the confusing way that you noticed. However the list of "related posts" is stored in a different table in the database and was apparently migrated correctly when Physics absorbed the first round of Astronomy questions.

The rise and fall and re-rise of Astronomy happened before I joined this community, but there are old posts on Physics Meta about it and probably someone else will chime in with an approximate timeline.

  • $\begingroup$ Well yea I'm posting this Meta question primarily to bring attention to the possible bug that affects the entire SE network. $\endgroup$
    – user21820
    Feb 15, 2017 at 6:33
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    $\begingroup$ What I remember offhand is that the old Astronomy site lasted for quite a while in private beta before it was absorbed into this site. There are definitely old meta posts here that will establish some part of that timeline. $\endgroup$
    – David Z
    Feb 15, 2017 at 7:15
  • $\begingroup$ The old astronomy site started public beta in June 2011 and it was shuttered in April 2012; the new one started public beta in October 2013. (The requirements for graduation / die-out were changed in June 2015, so it's much less likely that the new one will die.) $\endgroup$ Feb 15, 2017 at 14:21
  • $\begingroup$ The links to the old astronomy site should have been changed in the migration when it was shuttered, but it obviously wasn't completely effective. Post IDs are sequential, so it was inevitable that they would be reused. $\endgroup$ Feb 15, 2017 at 14:23
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    $\begingroup$ A quick query turns up 34 potential broken links, which should be fixed one-by-one, but probably over a few days to avoid choking the front page. $\endgroup$ Feb 15, 2017 at 14:29
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    $\begingroup$ ...aaand, they're gone. $\endgroup$ Feb 26, 2017 at 22:55

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