  Massive amounts of misinformation have been observed to spread in
uncontrolled fashion across social media. Examples include rumors, hoaxes, fake
news, and conspiracy theories. At the same time, several journalistic
organizations devote significant efforts to high-quality fact checking of
online claims. The resulting information cascades contain instances of both
accurate and inaccurate information, unfold over multiple time scales, and
often reach audiences of considerable size. All these factors pose challenges
for the study of the social dynamics of online news sharing. Here we introduce
Hoaxy, a platform for the collection, detection, and analysis of online
misinformation and its related fact-checking efforts. We discuss the design of
the platform and present a preliminary analysis of a sample of public tweets
containing both fake news and fact checking. We find that, in the aggregate,
the sharing of fact-checking content typically lags that of misinformation by
10--20 hours. Moreover, fake news are dominated by very active users, while
fact checking is a more grass-roots activity. With the increasing risks
connected to massive online misinformation, social news observatories have the
potential to help researchers, journalists, and the general public understand
the dynamics of real and fake news sharing.
