Also, the Aperture "Import settings" panel has a brick, "Backup Location". If you specify a folder, any image you import will be backed up to this backup folder on import, so you automatically will have a backup of your original files.
As this is in the Aperture list I will assume you are in some way using Aperture and that the 'photos' are in Aperture.
If this is the case you first need to define what you mean by 'photos'. In the world of digital imagery that term can mean many different things. The file from the camera, the file imported into Aperture, the versions you created of this file in Aperture, the files you exported of this image from Aperture.
So while dragging to the external drive might work for some of those it won't work for all. So if you could explain in more depth what your setup is and what you are trying to accomplish we might better be able to answer your question.
They are the RAW+JPEG files that I have imported from my Canon 5D. Just looking to copy/save/back up the folder in case something happens. I use Time Machine but would like just a back up of the file stored in Aperture's library.
Are the originals managed or referenced?
As Léonie pointed out you can have Aperture make a copy of the originals during import. This is one of the methods I use to back up my images. Then because my originals are managed when I backup (using the vault and by copying the entire library to another HD) the library the originals are saved again.
So when I'm done I have a copy of just the originals ( made during import), and two copies of the library with originals, one vault and one straight copy of the library.