open-uri only retrieving partial webpage

I am trying to scrape headlines from CNN’s homepage using nokogiri and open-uri, but whenever I do so, open-uri fails to retrieve the most substantial content on the page. When I use the following:

open(“http://www.cnn.com”)

the temporary html file retrieved only has the html of the navbar and footer (image link here), while all of the actual info I want to scrape is not included.

Anyone know how to fix this?