Perhaps the most impressive image - well, the one that impressed me the most - was the image of what you would see if you were to travel outside of the familiar confines of our galaxy. Because it was then that the planetarium dome simply went black.
If you go outside on a clear, cloudless night under dark skies, you will be able to make out thousands of objects of varying brightness: planets, stars, nebulas, globular clusters, the dim glow of the billions of stars in the Milky Way stretching across the sky - our own galaxy, seen from within. All of these objects are located within (or in the case of the globular clusters, in orbit around) our galaxy. With the naked eye, you might be able to pick out a faint patch of light in Andromeda, not far from the big M of Cassiopea. This is the Andromeda Galaxy, the farthest object visible with the unaided eye. Oh, there are plenty of other galaxies that you can see, but you will need a telescope to find them, and you will probably need the brighter stars in the neighborhood to help you zero in on their locations. There are also "ghost galaxies", low-surface-brightness galaxies (studied by my fellow member of the Pennsylvania Governor's School for the Sciences Class of '84 Julianne Dalcanton) that can be much closer and almost impossible to see.
Move outside of our galaxy and the Andromeda Galaxy will still be a faint smudge. And all those other galaxies will be much harder to find, because now you'll no longer have nearby stars to help you locate them - you left those behind when you left the Milky Way Galaxy behind. Move far enough away and even the Milky Way will be hard to see. You will be surrounded by empty darkness on all sides.
The space between galaxies is vast, and empty, and dark. I never really had a good sense of that until yesterday. It left me feeling a bit chilled. I was only too glad to step back out into the warm embrace of our galaxy, our star system, our planet, and my little corner of it.
A new show starts in November, based on Hubble Space Telescope photos. I'm going to try to see that one. You should catch "Big" if you can!
IF YOU GO: Tickets are purchased on the lowest level of the Museum. The Planetarium is on the top floor. So make sure you buy your tickets in advance, and be sure to be in the theater before the doors close! Check here for more information and a link to the planetarium's schedule.