“What’s the coolest thing you’ve ever seen through a telescope?”
People who know—or who learn—that I taught astronomy and was the director of an observatory with a half-meter telescope often ask questions like this. Variations on the theme include “What’s the most distant object you can see?” or “Can you see Pluto?” (Respective answers are: probably 3C 273, an unusually bright quasar that is 2.4 billion light years distant; yes, but it’s not much to see.) I’ve developed some stock answers over the years and can trot them out semi-automatically. But this was an old high school and college friend I had not seen for more than thirty years, and he deserved a more thoughtful answer. And since all of these objects are currently in the night sky, they came easily to mind.
Without a doubt, Saturn is my favorite planet of all, especially when its gorgeous rings are tilted so that they are more prominent. A 20-inch telescope and good seeing conditions will show the famous Cassini division, the shadow of the rings on the planet, and the shadow of the planet on the rings.
A spiral galaxy can present itself to us either edge-on, in which case the gas and dust in its spiral arms may obscure most of the starlight, or face-on, where the form of the galactic disk can be discerned from above the disk plane. M51 is the Whirlpool Galaxy, visibly interacting with a nearby companion.
But my favorite object of all is a globular cluster, a spherical collection of perhaps half a million stars, sparse at the edges and so densely packed near the center that individual stars are indistinguishable from a solid wall of light. The most prominent globular cluster in the northern hemisphere is M13.
The images I have included here approximate roughly what you would see through the 20-inch Gilbert Telescope at the Lynchburg College Belk Observatory. You may have found these images disappointing and wondered why I didn’t use some gorgeous images from the Hubble Space Telescope. The answer lies in the more extended response I gave my friend.
As beautiful as the Hubble images are, and as valuable as they are to astronomers, they are still just images on a computer screen. There is something about peering through a real telescope aimed at a real sky and seeing photons of light that spent hours or years or millennia or eons traveling to Earth. Their last few nanoseconds of travel bounced them around some mirrors and focused them through lenses so that those photons could enter your eye, fall on your retina and be interpreted by your brain. That rather bloodless description can’t begin to describe the numinous experience of actually seeing such a thing. The first time I ever saw M13 through a telescope, my eyes were not fully dark adapted and I could only see the bright central region. Slowly, as my eyes adjusted, more and more stars became visible at the outer edges. Suddenly it was as though someone had flipped a switch, and the globular cluster seemed to me to transition to a three-dimensional object. I actually cried out and stumbled back from the eyepiece. It was my very own David Bowman moment:
I am composing this on a computer, will soon upload it to another computer, and presumably you are reading this on a computer. But no computer or computer image can replace direct contact with nature, with seeing those photons that traveled all that way just to enter your eye.
And that’s the coolest thing I’ve ever seen through a telescope.