blazed along tree line then dissapeared.

A friend and I were talking, leaning against my car late one summer night. The crickets were out and chirping. For some reason we both stopped talking and a huge light in a triangle shape caught our eye. It was real dark except for a couple house lights on. It was over the tree line, not sure of distance, and it moved very slowly, what I would guess as about 20 to 40 MPH. The crickets stopped chirping as this thing moved. I could hear a faint "crackling" noise as it moved. There was no other sound as This is a secluded area. We held our breath as this thing reached a spot in the sky and rocketed at about a 75 degree angle out of sight, it did leave a faint light trail that lasted half a second or so and then was gone. We thought it may have been over the bangor sub base. If it was it was farther away than I thought and had to have been very large to have been that visable. A very unreal experiance and no one believes me.  I dont know what I saw but I do know that humans do not have that kind of capability, no airplane flies that slow with no noise then dissapears that quickly.
Date is approximate.  PD