I keep seeing a red light coming from the direction of my neighbors, and it appears randomly. It comes and goes really fast, so I can never get a picture of it. It always seems to be in the same general area, and it happens only at night. The light is a defined round shape and is large enough that I can see it from about 70 to 100 feet away.
I assume your neighbor isn’t a sailing vessel, flying craft, or the tail end of a train… How long does the light stay on? Does it always come from the same place? Does it move? Is it connected to when they come or go? It could just be a flashlight. Maybe you don’t notice it during the day because red light is hard to see in daylight. The only other explanation I can think of is aliens.
@Dario
No 
It stays on for just a second or two, almost like something triggers it. It’s hard to tell if it’s in the exact same spot, but it seems to be in the same 10x10 foot area when I look out the window. I think it might look different depending on where I’m standing, but it’s so dark outside that it’s hard to be sure. It’s not a light that moves around like a flashlight, so I ruled that out. I’m not spying on my neighbors or anything, but it might happen more than I realize. It’s just a really big red light that grabbed my attention and threw me off both times I saw it. The first time it happened was after nightfall, so I thought maybe I triggered a camera or something, but it was too big to be that. It happened again recently a few times in the span of an hour during the night. 
@Rafael
Aliens confirmed
Maybe it’s a motion sensor, camera, or even something weird like a laser mind control device?
OP, I think you might be overthinking it, or getting a little paranoid. The most likely explanation is that your neighbor has a security system with a motion sensor that sometimes shows a small red light. Those are really common. It could also be something like a smoke detector or even their TV or computer. All sorts of things could cause a red light.
@Hudson
No, it’s not either of those. It’s only happened twice, but it was really weird, so I wanted to explore some possibilities. They do have Blink cameras pointed halfway into my yard, and I’m familiar with the red lights on those, but this is a much larger light that pops up quickly and disappears. It doesn’t blink like a dead battery light either.
@Rafael
Could it be a kids toy? Or maybe a WiFi router or extender briefly losing connection?
Hudson said:
@Rafael
Could it be a kids toy? Or maybe a WiFi router or extender briefly losing connection?
No kids, they’re older, and it’s not a router. It’s definitely a bigger light than that, and it’s a very bright red. Also, it’s positioned higher than my fence line. So, unless an alien is standing in my yard with a red flashlight, it’s probably not that. 
The light is more like a flashlight size, but it’s not dispersed at all and it doesn’t move.
Could it be the brake light on their car maybe?
You really need to learn to ignore stuff like this.
Curtis said:
You really need to learn to ignore stuff like this.
Sheesh. I’m just trying to come up with some logical possibilities because I know it’s not their cameras. We’ve had neighborhood break-ins before, and they mess with my dog. Plus, our backyards share a fence, and there’s no one else around.
@Rafael
I get that, and I’m not making fun of you. I’m just sharing what you asked for.
Now I’m thinking about installing a random red light to mess with my nosy neighbors. Thanks for the idea.
luke said:
Now I’m thinking about installing a random red light to mess with my nosy neighbors. Thanks for the idea.
Haha, I wish I had thought of that! They’re super nosy, like peeking around the fence and pointing their Blink cameras into my yard. That’s part of why I’m curious if they were doing something else. I only notice it because it’s coming straight into my door, and it’s bright enough to grab my attention. Oh, and my dog was growling right before I saw it.
It could be attached to some device or system. If it’s deactivated, the red light signal might still be visible from the outside.