view iPhoto back up from External Hard Drive

I've been backing up my MacBook Pro to an external hard drive via time machine. Today I tried to view these photos, and I can't figure it out. When trying to open the backed up iPhoto library directly from my external hard drive, I get this prompt "The iPhoto library is a Time Machine backup, and so cannot be used as the main library. Reopen iPhoto with the Option key held down to choose another library."

If I open iPhoto and use the time machine tool, I reached the point where I was able to import the photos to my library again, however there isn't enough space on my Mac to do so. And, I don't want these photos on my Mac. I just want to view them.

Essentially, I just want to view the photos that I have backed up on my external hard drive. How do I do this? Thanks!