On Tuesday things moved into high gear. Mike Brotherton kicked off the day with a long lecture about the electromagnetic spectrum, photon energies, emission and absorption, and how telescopes work.

After a lunch break we resumed with a talk by Dr. Danny Dale on infrared astronomy and dust in space.

Jim Verney followed that with a laboratory session in which we all got to use diffraction gratings to observe the emission spectra of various ionized gases. Argon and Oxygen were disappointing, Hydrogen and Helium were good and visible, but the real stars of the session were Mercury and Neon. With the aid of our diffraction gratings we could actually see the spectral lines peculiar to each element.

Both Dr. Brotherton and Dr. Verney mentioned a fact which is obvious but becomes rather profound when you think about it. Virtually everything astronomers know about the Universe — and therefore pretty much everything we as a species know about the Universe — is gained entirely by collecting and analyzing electromagnetic waves. X-rays, gamma rays, ultraviolet light, visible light, infrared, microwaves, and radio waves are the tools astronomers use. Over the past four centuries they've gotten very good at squeezing every last iota of information out of the waves they catch.

In 1848, the philosopher Auguste Comte used the physical composition of distant stars as an example of something which could never be known — they were too far away, so humans could never reach them to take samples to analyze. Less than a decade later the development of spectroscopy meant that astronomers could tell exactly what stars are made of. Now they're even trying to see planets of other stars and determine their composition. All with light.

After our lab session we hunkered down for another firehose blast of information, this time from Dr. Henry Stratmann, speaking about space medicine and health hazards of space travel. He covered pretty much everything one could possibly want to know about the subject. We learned about the effects of decompression, acceleration, space debris strikes, body rhythm disruption, radiation, and microgravity. Since the audience was a group of writers, we were especially interested in the psychosocial hazards — i.e. the chance of astronauts killing each other or going bonkers on long missions.

Dr. Stratmann also briefed us on the state of the art in orbital medicine. The short version: don't get sick in space. Your doctor may or may not be a physician, and is working with a medical kit about as well-equipped as the average ambulance. If you need surgery, your doctor will have to worry about blood droplets, infection control, and floating viscera.

After that we broke for a hearty dinner. It was too rainy for skywatching, and the attendees too tired for movies, so we all went off to bed. Tomorrow: Orbital Mechanics!