4 silently flying orange elliptic lights cary NC

we were visiting a couple of friends and I was on the patio with 5 other people. One person spotted an orange light flying across the sky to the left of the house. We are all world wide travelers and so, we knew this was not an airplane (that we know of). It was going in a rather straight trajectory without making a sound. We all looked and then, 3 other similar lights followed in a similar trajectory at a 10 min or so interval.