The NASA APOD site is currently not responding. I notice that main NASA Goddard Space Flight Center site http://www.gsfc.nasa.gov/ is also not responding, so I would guess there is a general problem with connectivity at NASA's GSFC. I would expect that this would be solved soon after the system people arrive at work at GSFC, likely by 9 am or 10 am EDT. More recent information will be posted here at it becomes available.
- RJN