Via last Thursday's APOD, I came to this site where I downloaded an excellent, high-res video about some recent research out of Germany. Over the last 16 years, a team of astronomers have taken images of a tiny patch of sky that is the very center of the milky way. By doing this they have been able to analyze the motion of 28 stars that are orbiting a supermassive blackhole that is the center of our galaxy.
I highly recommend the full video (232MB .m4v) but here is a small taste of the phenomenon from youtube:
One of the star's orbits is only 16 years long, and it gets as close to the blackhole as just 5x the distance from the sun to Neptune! But it is moving a heck of a lot faster because Neptune's orbital period is 164 years.
Anyway, check out the video it is a very fascinating thing to watch those stars in motion.