Steady light travelling at a high velocity across the southern dark morning sky.

At 5:45 a.m., I went outside to observe the alignment of the 5 naked eye planets.  After spotting Jupiter furthest west in the southwest sky, I observed a round object with the same brightness of Jupiter (not as bright as Venus) travelling at a steady but fast rate in front of the background stars.  
Because the sun was not up I could not tell if the object was in our atmosphere although it was not severely refracting light as it would if it wasn't.  It appeared to be at a very high altitude and was travelling at a velocity inconsistent with the speed of commercial jets.  The moving sphere was round and looked like a planet.  
I ran to my daughter's room so she could witness it too by the time we returned (15 seconds at most it was gone).  That time period would not have been long enough for object to breach the horizon.  My best explanation is that it was a high altitude military aircraft or a satellite reflecting the rising sun.
Witness elects to remain totally anonymous; provides no contact information.  PD