We have added a new authentication endpoint — Twitter! Now you can sign in even if you don’t have Facebook account. Just click on the “Sign in” button, choose the “via Twitter” item from the drop-down and confirm the authentication dialog.
Please notice that the dialog gives a guarantee that the access level is read only. We cannot post tweets from your authority, manage your followers, change your password, etc.
Confirming the dialog, you just provide to us your screen name (@NASA, let’s say) and your internal Twitter ID (a long number that identifies your account).