My boyfriend and I were walking home from dinner. I'm a scientist and a keen yet amateur astronomist, so I regularly look up into the sky to see what planets and constellations I can see. We ate at Pizza Buona on Sunset and were walking on Sunset Blvd heading east, back to our house when on the corner of Sunset and Park I looked up at the almost full moon and noticed a red pulsating light in the sky. I told my boyfriend, he looked, we speculated, hmmm looks like the color of Mars but I said it's oval or star shaped like Saturn yet it's the size of Jupiter. The light we saw was just left of the moon, and we were walking east, the moon was to the southeast of us so the UFO was southeast of us as well but just north of the moon. I have a sky viewer app so I pulled out my phone to see what planet it was. Here's where it got weird: We both noticed the "planet" was moving slowly, I personally couldn't say it was moving quickly or in any particular direction but there appeared to be motion. It got smaller, like the star shape went away, it went from being oval/star shaped and pulsating to being really small, still red still pulsating and then it was just GONE. By then I had gotten my phone out, opened sky viewer and it didn't show that there were any stars, planets, or satellites anywhere near the red light. I did notice, however, that there were 2 distinct contrails in a V formation north and south of the moon and the unidentified object, they literally looked like a right side up V on either side of the moon and where the light was. I have zero idea if this part means anything, but as a scientist, particularly a biologist, I understand detailed observations, are critical. I didn't at any time see a plane or a helicopter, just the contrails but shortly thereafter I did see a plane and a helicopter but not as high up or in the same place. Which is not unusual, there's a few airports kind of nearby and a our neighborhood is on a helicopter route. It bears emphasizing that I know what a plane looks like in flight, and a helicopter, in the day, at night, when it's cloudy, dark, bright, low, high up, ect. and this WAS NOT a plane or a helicopter. for sure. It was up high, equal to wherever the moon was in Los Angeles at about 11:30-ish on July 11th. I honestly thought it was a planet for 90% of the time it was visible, from the size, the color, the pulsation, the angle, then it suddenly moved and or shrank either in a quick succession or simultaneously. I was shocked, but my boyfriend agreed that it happened pretty much exactly as I've stated. Sorry I don't have any additional info or details, it was a weird occurrence and I'd love a rational explanation.