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.

He had to to keep her from burning up and dying as a result of the Meta-crisis. Her human brain was unable to long sustain the vast knowledge, powers of perception, and intelligence of a Time-Lord, and it was killing her. So, the Doctor erased her memories of their time together to save her life. With this, the Donna Noble she had become died that day. Also if she remebered her travels with the docotr even for a second she would burn up.