I was an expert on planetary astronomy when I was young. It wasn’t that I was a scientific prodigy, it’s just no one knew much about the solar system back then. I read every book in the library about astronomy. It didn’t take long. They all provided me the same information: a planet was about so big; it rotated on its axis in about so many hours or days and went around the sun in so many months or years. And that was that. As far as I could tell, four pictures had been taken of the outer planets: one of Uranus, one of Neptune and two of Pluto. The Pluto pictures were taken a few days apart so you could see the movement of a very unassuming dot against a static background of stars.
We had sent spacecraft to Mars and Venus by then, but the Mariner spacecraft had taken only a handful of pictures at Mars and the ones that flew to Venus didn’t even have cameras. It was the 1970’s that brought the planets to life. Every year, it seemed NASA was journeying where no spacecraft had been before. I saw a sunrise from Jupiter, courtesy of Pioneer 10. That was kind of underwhelming; it was a gray blob on the black and white TV set in the den. Later on I saw Viking 1’s pictures of the surface of Mars on our color set. The sky was supposed to be blue (according to the books), but it turned out to be pink.
The old astronomy books were so confident. Of course Mercury was locked with one side permanently facing the sun and the other draped in the darkest night. Everyone knew there was plant life on Mars. It was obvious Venus was covered in an ocean of seltzer water… or petroleum… or a desert. But the planetary scientists in the late seventies didn’t seem to know as much as their counterparts who wrote the books in the fifties. But they were okay with that, even happy about it. I remember watching the news when the Voyagers passed by Jupiter, then Saturn. The scientists shook their heads and smiled in mute wonderment as they showed off some new, totally unexplained phenomenon sent back from space like kids opening up their gifts on Christmas morning.
While the astonishing discoveries in solar system science have declined since then, there are still plenty of mysteries. The first close up pictures of Pluto won’t show up until Daniel can drive a car. Even such well-traveled planets as Mars have fresh surprises. Scientists still throw up their hands when trying to explain some of the data; it’s a tradition on the NASA channel. However, many of the spacecraft also store their data on the Internet these days and interested laymen such as myself can feel just as wonderfully ignorant in face of the latest wonders displayed on my monitor. And over the past twenty years, more than three hundred planets have been discovered outside the solar system. Until the Hubble Space Telescope took a picture of one, almost nothing else was known about them except they were about so big and took about so long to go around their parent stars. Sound familiar?