Sorry for not posting sooner. I've been very busy, and still am. Just so nobody thinks I'm dead, here's a few recent photos from the "Astronomy Picture of the Day" site.
Above, that's Dingo Gap on Mars as seen by the Curiosity Rover.
How big is our galaxy? VERY. Our galaxy contains an area equal to that occupied by all six of the galaxies shown.
Here's (above) the center of a nearby galaxy. The stars are so densely packed, so close together, that a person standing on a planet there would see nothing but extremely bright light in all directions, all day long. I can't even imagine how intense the ambient radiation would be.
If intense radiation was confined to a small area in the very center of galaxies I wouldn't bother worrying about it, but I think it's more widespread than that, and may seriously hamper our ability to explore the galaxy and find intelligent life.
Above, the Earth at night as seen by the International Space Station.
Here's (above) the surface of Enceladus, a moon of Saturn.
A super massive black hole at its center leads astronomers to guess that it's the remnant of a larger galaxy that was torn apart by proximity with something else.
This (above) is the Earth seen from from a distant probe. From this angle the Moon seems close enought to Earth to scrape it. This is exactly the way Wally Wood used to draw planets and their moons, way before there was any photo reference for it.