no noise, no dirt stirred up, two identical crafts never seen before, the ability to hover without making a sound

I have a blog that tells of the experience http://((blog address deleted)).blogspot.com/  
The craft was round in shapr and had 3 large oval lights in a tight configuration to the front of the craft and these lights blinked in succession  of red, white, green.
It was complertely silent and rose no dust or dirt while hovering in our backyard. We took a picture of it because it would float by each night at the same time -when I took the picture and the flash went off -four large red lights flashed on at the bottom of the craft blinking in this order first, third, second, fourth 
The object was quite large and as it went over our building I noticed that the bottom of the ship was a huge conglomeration of microchip configurations-there was no empty space except the space occupied by the lights. It appeared to have a mesh or screen like covering over the bottom-this had to have some sort of feet to land, there is no other way.
Witness indicates that the date of the incident is approximate.  PD