I sometimes can spot why: it happens that there is a 'big' thread going on on HN and sometimes a Wikipedia article about one of the aspect of the thread or an a

I sometimes can spot why: it happens that there is a 'big' thread going on on HN and sometimes a Wikipedia article about one of the aspect of the thread or an argument in it is posted. I have also seen two articles on the front page that seemed to be part of the same discussion. Eg: an article about Tokyo gentrification would trigger a discussion about waste management in big cities and then Wikipedia articles about Japanese sewers and some aspects of Japanese culture would be posted.