"Light from a Distant World"

17 December, 1999

We've finally reached the future.

Since I've been a science fiction fan longer than I can remember (Thanks, Mom, for reading Heinlein to me when I was a toddler!) I've always had specific iconic notions in my head about things we will be able to do in the future.

It's true that my life is full of a lot of everyday notions that seemed like far-out sci-fi when I was a kid. But flip-phones and microwave ovens and VCRs aren't quite as exciting and cool as a Star Trek communicator, a food synthesizer, or a self-aware house computer.

But this week we really crossed the line into the future. Ever since I understood enough about astronomy to know that stars are objects similar to our sun, just very, very far away, I've wondered about planets orbiting those stars. Most scientists have believed for a long time that they must exist. In fact, as we've learned more about stars, how they're formed, how they die, and how new ones are created from the remains of old, it's become almost a certainty that they exist in vast numbers.

And, barely four years ago we finally detected one. Swiss astronomers Didier Queloz and Michel Mayor detected wobbles in the light of the star 51 Pegasus, wobbles caused by the gravitational pull of a giant planet. Soon, a many other astronomers confirmed Queloz and Mayor's discovery. Scientists never saw the planet itself because it was lost in the glare of the much brighter starlight. But they could calculate its mass, how closely it orbited its sun, and how fast it was moving in that orbit.

Since then, several other planets have been discovered in a similar way. Because stars are so huge, while by comparison even giant planets (such as Jupitor, the largest planet in our own system) are like tiny pebbles, the methods used so far can only detect the largest planets in each system. They are the only ones with enough gravity to make the star visibly wobble. We have been able to detect more than a wobble. Scientists have recorded the shadow of one of these large planets as it passed between us and its parent star. Being able to see how much of the star's light it blocked out and how long it took to pass across the face of its sun, they could independently confirm the characteristics of the planet they had infered from the wobble.

In 1997, astronomers Geoffrey Marcy and Paul Butler detected similar wobbles coming from the star Tau Bootis, which is 55 light years from us. They calculated that the planet was a giant one orbiting extremely close to its sun. By then, this was just another in a rapidly growing list of extra-solar giant planets.

A team of British astronomers at the University of St. Andrews, led by Andrew Cameron, have collected light coming from the planet. They collected readings of Tau Bootis for nine consecutive days at a time when, according to the orbital calculations made earlier, the planet would be in a position the reflect light towards us, just before disappearing behind the star. Then, using computer models, they subtracted out of the images the average light coming from the star. They were left with a faint signal, 20,000 times dimmer than the star. But they could measure a detectable doppler shift, which corresponds to the predicted orbital speed of the planet. They were also able to calculate the planet's diameter. Since we already had a good guess on its mass, this lets us calculate its density and make some general guesses about the chemical composition of the planet.

In a few more months, the planet will come out on the other side of Tau Bootis, giving astronomers all over the world a chance to try to duplicate Cameron's work. If they do, we will eventually be able to tell much more about this planet than just its mass, distance, and speed. We'll be able to analyse the spectrum to learn the chemical composition of its upper atmostphere. We can calcuate the temperature of that atmosphere, and chart it over time.

When I first began wondering about planets orbiting other stars, I knew that someday, far in the future, we would be able to see those planets. We would know what they were made of, what their weather was like, and what it would be like to visit them. The first step to all of that was to be able to see them.

And now, we can.

Yes, I still hope (and pray) that humankind gets its act together enough to explore our own star system. And I dream that someday, somehow, people from our world will actually set foot on some distant world orbiting another star. But for now, I'm going to sit back and let the giddy joy of this accomplishment wash over me. It makes me grin like an idiot every time I think about it. When I first heard the news I stopped and did a little dance. It was so amazing.

I never, ever dreamed that in my lifetime we would actually see those worlds. It's the future! We made it!

But I'm still holding out for my personal rocket pack.

Note to the readers: I'm taking a couple weeks off work for the holidays. The essays will continue throughout, but on a slightly irregular schedule. Happy Solstice!

This page is copyright 1999 by Gene Breshears. Photograph is copyright 1998 by Julie Rampke. All Rights Reserved.