Rectangular UFO Viewed Up Close

Sighting was approx. July 1988 100km to the North East of Halifax Nova Scotia Canada at 12-1AM.
I and three other individuals noticed a large object emitting light travelling directly over our vehicle.
The object was rectangular and approx. 200 feet by 100 feet in size. It was so close overhead and so bright that if caused a glare on the windshield. It was maybe 200 feet above us, maybe closer.
The entire underneath was illuminated by what looked like an electrical glow. Colours were blue, green and some orange in a swirling pattern.
We stopped the car as the object travelled from the North to the South. It drifted slowly (maybe 50km/h) on a clear moonless/windless summer night making no noise, and was still drifting when we got out of the car.
We were standing outside looking at it as it came to a stop maybe .25km from us. I had a pretty good look at it and can say for certain it was about 20 feet think and black or very dark in color. It was a dark night but the lights underneath the object were fairly bright.
After about 3 or 4 minutes the object then “charged” up glowing bright and then shot off to the South West at an incredible speed. It reached the horizon in approx. 1 second and disappeared into a dot of light.
I know of at least 2 other sightings of this object by people I know including a daylight sighting where the object was a few hundred feet overhead. In that incident the observer saw a smaller rectangle that was red and silver checkerboard color.

Sighting was in Nova Scotia approximately here
google map link
https://www.google.ca/maps/place/Barren+Rd,+Middle+Musquodoboit,+NS+B0N+1X0/@45.065397,-63.0712362,17z/data=!3m1!4b1!4m5!3m4!1s0x4b5bdcc45fc19fcb:0xeecb3fbbb6d45462!8m2!3d45.065397!4d-63.0690475