Dream about the world ending??..?

I was dreaming the other night, and I had a dream that i was in my room on the computer and on the phone with my mother , when I went upstairs to my parents room and when I went up staris to talk to them they told me the world was ending. When i went back to my room to get the phone to call my mother back, i looked out the window, only to realize that there was a huge planet, thousands of miles wide, about to hit the earth, and i tried to call my mother back but the phone lines were down, and then i woke up. I am really scared about this dream, and im wonderin if i means anything, if you could lease help me with thi it wold be greatly appreciated. Thanks.