A question about recover database untile time

  As  follow you can see ,not all time can be recover to. What's the reason for this?

How can I know which time I can recover before I recover database?

How can I recover database to more time When I create database?

 

SQL> recover database using backup controlfile until time '2010-12-19 00:30:00';
ORA-00279: change 11643154179367 generated at 12/19/2010 00:21:13 needed for
thread 1
ORA-00289: suggestion : /data1/mcse/asrs/arch/arch_1_12177.arc
ORA-00280: change 11643154179367 for thread 1 is in sequence #12177

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
auto
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01195: online backup of file 7 needs more recovery to be consistent