Anne, good theory.

We don't need to use spoiler fonts in this thread, people. Except for the window between when it airs in the UK, and when it airs in th US.

Thank you for the clarification, Tom. I'll edit my posts accordingly.

io9 sez the episode was Quite Possibly the Best Doctor Who Season Opener of All Time

Also, my current theory: The astronaut who kills the older Doctor is a much younger Song.

I thought I saw a flash of hair that looked like River's, so, yes, I thought it was River too, but if it's a younger River, wouldn't the current River remember having killed the Doctor?

My pet theory at the moment is that the astronaut is the Doctor.

That was my first guess as to who it was before I saw the flash of hair.

I loved that Pond's reaction was to take a picture of it as evidence and try and remember it. That's agency, baby.

That was great! Except now she doesn't remember she has the photo! We have to wait until she's just looking at the photos on her phone for no reason and stumbles across it.

On the plus side: P-C's review that paid attention to details.

Thank Mark for that. Since he'd seen "The Lodger" more recently than I had, he recognized the pieces of the machine even before we saw the whole thing. And then after the episode we spent like twenty minutes looking up theories and watching bits of past episodes for clues.

but if it's a younger River, wouldn't the current River remember having killed the Doctor?

Perhaps she does. She has said that she killed a very good man and she's the one who's most insistent that they not interfere and tell current Doctor what's going on. She may know what potential ramifications are and still does it because she loves him and will do what's ultimately best for him/the Universe. She shoots at herself but misses? Come on-- we've seen her shoot a Stetson from many paces.

I like the it's yet another iteration of the Doctor theory.

I wonder, too, if it could be the Master. Oh, to see John Simm and Matt Smith on screen together.

We have to wait until she's just looking at the photos on her phone for no reason and stumbles across it.

That's going to be the most nerve wrecking who's on first sci-fi scene. I hope they'll spare it from us.

You know, sort of lost in all of this, is how things are going to change with Amy's pregnancy. The Doctor, being the Doctor, is going to be bemused, as he is by most things human, but will otherwise progress as usual and continue to thrust Amy into perilous sorts of situations and Amy, being Amy, will rush headlong into them.

It's going to be Rory who steps up and puts the brakes on, occasionally, which is going to create some lovely, lovely tension, especially between he and the Doctor.

Oh, Moff, you crafty bastard.

Oh, to see John Simm and Matt Smith on screen together.

You've got my vote.

She has said that she killed a very good man

And it was implied it wasn't the Doctor. Or at least, the version of Doctor that was in question, a season or two ago.

I need to re-watch that scene and see if I can get a read off of River: whether her reactions make sense with having seen the scene from the other perspective (and, one assumes, additional knowledge).

eta: It could also be the little girl who's in the spacesuit in '69, all grown up, which would make something like sense, as well.