Any Questions?

As an Observing Guide for the Nightly Observing Program, I really think I've got it made. Running a 16-inch telescope under these skies is a real treat, and I knew it would be when I applied for the job.

There is another wonderful aspect of conducting the NOP, however, that I did not predict. I never expected the guests to be so interesting and to ask such great questions!

I take the task of explaining science to the public very seriously, and see every question as a challenge. Some questions I hear regularly, and these are usually easy to answer ("What's a black hole? What are Saturn's rings made of? Have you ever seen a UFO?" One day I may write an article answering these questions and others like them). At other times I get questions that I simply do not expect. Some of these are real stumpers, and others catch me off guard with an unusual point of view. These questions are always memorable for some reason, and they are the ones I enjoy getting the most. Let me share a few.

On one evening, after talking for quite a bit about the births and deaths of the stars, one woman asked, "With all these stars forming and dying, how many constellations have come and gone?"

This is actually a brilliant question. If stars come and go, the patterns of stars people see in the sky should come and go too. I explained that while stars do change, these changes take millions or billions of years. The oldest recorded constellations are only a few thousand years old. Every constellation ever recorded by any culture in any era is still visible in the nighttime sky. Humans are mayflies compared to the stars.

On another evening, we pointed the telescope at the Crab Nebula, the remains of an exploded star (picture at left). When I mentioned that the Crab Nebula is in the constellation Taurus, a guest spoke up: "Isn't the Crab Nebula in Cancer?" I gently informed her that it was indeed in Taurus. "Are you sure it isn't in Cancer?" she persisted. "Because in astrology that's usually how it works." Oh dear, I thought. When I am asked about astrology, I usually apologize and sheepishly say that I know nothing about it. Other astronomers might not be so kind. But I suddenly made the connection.

Cancer, the Crab. Of course the Crab Nebula should be located there! But unfortunately these two crabs have nothing to do with each other. The constellation Cancer (see right) was invented by the ancient Greeks, who looked up at a pattern of stars and, by playing "connect-the-dots", saw a crab in the sky. The nebula known as M1 was nicknamed the "Crab Nebula" by a nineteenth-century astrophotographer who thought that the thin filaments of gas in the nebula (invisible to the unaided eye) looked like crab's legs. The nebula didn't even start to form until 1054 A.D., well after the time of the ancient Greeks.

Well, the Orion Nebula is indeed in the constellation Orion, and the Andromeda Galaxy is in Andromeda, although these objects were named after the constellations they inhabit. But what if the Cat's Eye Nebula was in Lynx, or the Swan Nebula was in Cygnus? Should the Horsehead Nebula really be in Pegasus? I think I like the idea of finding the planet Mars perpetually trapped in Aries (although technically Aries is the Ram, not the God of War). If you know your deep sky objects, try coming up with your own relocations. It's fun once you get started.

I also get plenty of questions that stump me. I try to remember these questions so I can look up the answers and be ready next time, but sometimes the answers are not easy to find. Here's a sample:

"What was the supernova that got Tycho Brahe's attention?" I know it was seen in Cassiopeia in about 1572 and that it had a profound effect on Tycho's life, but that's it.

"Have you ever heard of Auger's Law?" This was totally out of the blue. I later found out that there is an Auger Effect, which describes how electrons can be ejected from atoms.

"How do we know that white dwarf stars aren't undergoing fusion in their cores?" The answer is a long one. Basically, these stars are so dense that the atoms in their cores can't move around enough to crash into each other and stick. Ah, but how do we know that these stars are so dense? Questions that start with "How do we know..." are, I think, among the most challenging to answer. I have actually been asked the white dwarf question twice (!), and I'm proud to announce that I was ready the second time.

In addition to questions, guests tend to make very memorable comments. One of my favorites occurred while pointing the telescope at the moon. I mentioned that we were looking through a neutral density filter, which blocks light of all colors so the moon is not so blindingly bright. A clever guest, obviously employed by a large business, replied, "A neutral density filter? That's our human resources department."

The comments I appreciate most are when guests express their gratitude at the end of the program. For example, "Four years of education in just three hours!" and, "When did you get your Nobel Prize?" I hope this article can stand as a token of my thanks to them, since without the guests, the Nightly Observing Program and the Advanced Observing Program would be impossible. I'm going to indulge myself by ending with my all-time favorite quote, uttered at the conclusion of a recent program. I hope I can live up to it.

"Dr. Sagan would be proud!"