Slowly pulsing green light with white light underneath.

I was leaving a friends house when I noticed a green light slowly pulsing low in the western sky. At first, I thought it was just a plane but after a minute or so of watching it, I realized that it was not making any noise and was setting stationary in the sky. I got in my vehicle and drove approximately a third of a mile through the neighborhood and stopped when I found a safe spot to pull over. When I exited my vehicle, I realized it was emanating a white light underneath and was almost directly above me. After standing there looking at the object for a few seconds, I was overcome by an unusual sense of uneasiness and got in my car and left the area. As I was driving away, I saw it again, still setting in the same area about ten minutes later, but as I was on a busy highway, there was no safe place for me to pull over and observe the object further.