Pulsating Red/Green/White light off Puerto Rico.My wife and I were recently on a NCL cruise when I spotted something strange from the balcony one night. It was 10:15 PM local time (11:15 PM EST), and we were approximately ½ ways between the Dominican Republic and Puerto Rico. My guess is we were 25 miles north of the two islands, traveling due east and closer to Puerto Rico than the Dominican Republic. The sky was crystal clear and the visibility excellent when viewing the horizon. Looking straight up was diminished due to the ships lights.I went out on the balcony and immediately spotted a pulsating white/red/green light to the south, approximately 30 degrees above the horizon. The object was stationary and appeared to be rotating. The color changes were at regular intervals of approximately 1 second each. There also appeared to be a solid white light just above and attached to the color changing lights.After a few minutes my wife came out and I showed her what I was looking at. We both confirmed the color changing and the stationary aspect of the object. We continued to view the object for 15 to 20 minutes. In that time the object did not move up, down, or side to side at all, nor did the intensity of the lights change. What ever it was, it was definitely in a stationary position.The object did not appear to be close. I would guess it was 10 to 20 miles away as its relative position did not change in relation to the stars in the background and the motion of the ship. I was very tempted to call the bridge and ask what they thought of my sighting, but eventually never did.It is worth mentioning that my wife and I live in New England, close to the ocean and just a few miles from a major airport. We have seen thousands of airplanes over the years and often watch them come in over the water from 20+ miles away. Never has one appeared like this. Airplanes at a distance at night start off as a solid white light, move left/right/up/down, and then as they get closer the red and green wing lights come into view. The object we saw that night did not move at all and was easy to reference to the stars in the background. The red and green was also just as bright as the white.I am a casual astronomy enthusiast and fairly literate with the movements of the planets and constellations. The object we witnessed was far below the planetary arc and could not have been Venus or any other planet. In luminosity though I would say it was as bright as the brightest Venus I’ve ever seen.((NUFORC Note: We suspect a sighting of Sirius. We will contact source. PD))