Economy and dollar value

[Lindsey]

I'm hoping someone here knows a little more about this and can help me out. I know the American economy has been sliding down, and as of now the Canadian economy is still pretty good, although all this stock market crashing does affect us too, just hopefully not to the same extent!!! Anyways, at the start of this year, our dollar was equal to $1.10 American. It went down to about equal, and then I was thinking it would probably go back up again because all the recession talks started in America.
Anyways, yesterday I heard that our dollar was going way down again, and my mom called me to tell me I should think about exchanging some money for my trip before the dollar gets too low. I was like "Well, it might go back up, right?" and she told me I should try talking to someone who knows more about it! I checked today and we're down to $0.85 USD!!!
Soooo does anyone know what exactly affects the dollar value? I really have no clue. I just know that if our dollar keeps slipping, I need to exchange a lot of money asap. I've been saving for months and I want to actually get something out of it!!