Didnt have time to run inside and grab a camera.
Really weird aircraft - dark outside, couldnt make out everything.
It appeared to have a delta-wing configuration - but it was very large - 737 size at least - no more than 800 feet up - relatively quiet engines - didnt sound like a military jet - not even as loud as a civilian airliner - considering the altitude it should have been very loud I would think. Very slow too - I'd guess 150-200 MPH max.
Normal lighting as you would see from an airliner - red white and blue lights (wing, center, wing respectively) but I didnt recognize it.
Willow Grove NAS is about 25 miles away, but Ive only seen 130's, 18's and A10's fly out of there.
Anyone got any idea what it might have been? Ive never seen a 737 size aircraft that looked like one of the F16 delta wing concepts.
EDIT: Better example - a Concorde like shape, but with a wingspan far exceeding the fuselage in length.