Why the command "last reboot" returns several items including "still running"

Question

and the time is not my system time? For example

reboot   system boot  4.2.0-16-generic Mon Nov  9 20:48   still running
reboot   system boot  4.2.0-16-generic Mon Nov  9 20:45   still running
reboot   system boot  4.2.0-16-generic Mon Nov  9 20:41   still running
reboot   system boot  4.2.0-16-generic Mon Nov  9 20:37 - 12:41  (-7:-56)
reboot   system boot  4.2.0-16-generic Mon Nov  9 19:45 - 12:41  (-7:-4)
reboot   system boot  4.2.0-16-generic Mon Nov  9 14:48 - 06:50  (-7:-57)
reboot   system boot  4.2.0-16-generic Mon Nov  9 04:03 - 06:50  (02:47)

My system time is 12:40, not 20:40, 20:40 is my local time.

Can someone here tell me why? Thanks