Ask a question in the box below, or search using the box above.

As you enter your question, our massive, TARDIS-sized computers will search out other similar questions. So be sure to check the list that pops up before asking your question. Once you've decided that your question has not been asked before, push the not-so-threatening blue button below.

If you want to ask questions needing speculation or people's opinions, please do it in our Watercooler forum, not here. The main Q&A space is for questions with definitive factual answers. Thanks!

To avoid spoilers in the main Q&A section, please do to not post information about stories that have not been released in the UK, or ask for information about stories that have not yet aired there.

The cracks definitely erased at least the 2009 Dalek invasion, from series 4. The fact that Amy didn't know what the Daleks were was what tipped off the Doctor to the fact that something was erasing history.

The show hasn't given us a catalog of exactly what was and wasn't erased from past stories, and almost certainly never will. From off-camera, we know that Moffat's intention was to change the Whoniverse so that humans in 2010 wouldn't be blasé about the idea of alien invasions, so most likely, anything that was public knowledge, and wasn't covered up effectively or explained away, has been erased. He explicitly said that this didn't include everything from series 1-4, just a handful of stories, and the only classic story he could think of was "Nessie in the Thames" ("Terror of the Zygons"—ironically, that one actually had been explained away in a later episode), but that's really all we know.