Seth Shostak

It's the default premise in science: If you observe something in nature only once, you assume that what you've seen is typical. That's because 'typical' is just another way of saying 'most probable.'

The bottom line is that the position of the Sun relative to the stars slowly changes for any given date, and over the course of 26,000 years, it can easily slide between constellations. So you may think you're a Pisces, but you're actually an Aquarius.

Today's voguish threats, including climate change, population growth, massive war, and resource depletion, are all amenable to a fix if we act prudently. And even if we don't, these problems are incapable of obliterating all of humanity, let alone destroying the Earth. No, the real End of Days will happen slowly, as the Sun ages.

Just knowing that there's somebody else out there - that what's happened on this planet has also happened in many other places - that might change our lives in a very subtle way, but it's interesting to know and worth looking for.

The ideas of science germinate in a matrix of established knowledge gained by experiment; they are not lonesome thoughts, born in a rarified realm where no researcher has ever gone before.

Television is ephemeral, a fact that some will find reassuring. But earthlings will continue to pump the kilowatts into the ether. And eventually, when those signals have washed over a few hundred thousand star systems, someone may notice.

Engineers are now experimenting with 4,096-line TV systems, suggesting that with the next generation of sets you'll be able to count the grass blades on the Superbowl field, an obvious lifestyle improvement.

Any society that could come here could pick up the lights from New York. What should we do about that? Should we darken New York from now until the last human expires? Would we want to turn off all the radars at JFK airport?

I still remember my dismay in the summer of 2007 when - for the first time in the history of planet Earth - America's share of auto production dropped below 50 percent.

Certainly the history of astronomy shows that every time we thought we were special, we were wrong.

I got interested in astronomy at the age of 8 because I was looking at an atlas of the planets in my parents' apartment in Arlington, where I grew up. I got a telescope at age 10, which is pretty normal, and by the time I was in eighth grade, I had already seen a lot of cheesy sci-fi films.

When was the last time you bought an American-made radio or television? If you're Gen X or younger, the answer is 'never.' Does the label on that shirt or skirt you're wearing say 'Made in the U.S.A.'? If so, you probably got it at Goodwill, or maybe at a Smithsonian garage sale.