It's easy to wish upon a star — but if you want to make a living studying them, things get quite a bit tougher.

Take a look at any astronomy-themed Web site, or tune in to a science television program, and you're sure to be dazzled by the wonders of the universe. Black holes! Dark matter! Colliding galaxies!

What you won't hear is what many graduate and post-doctoral students in astronomy today know all too well — permanent, tenure-track jobs in the field are rare.

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The American Astronomical Society has a membership of 6,500, a modest figure to begin with. But, as its Web site states, that number "includes physicists, mathematicians, geologists, engineers and others whose research interests lie within the broad spectrum of subjects now comprising contemporary astronomy."

Each year, American universities graduate around 125 new Ph.D. astronomers into a job market, with a considerably lower number of tenure-track positions.

For example, last month the American Astronomical Society's online job register listed 31 tenure-track job openings.

Competition for those spots is naturally fierce, as documented among other places by a Web site known as the Astrophysics Jobs Rumor Mill.

It's a fact: The field of study with the largest subject matter of all — the universe itself — has a very small window of opportunity for those who want to do it full-time.

Many in the field point out that there are plenty of astronomy-related jobs involving data analysis, instrument-building and the like, and these positions will certainly put one into contact with astronomy all day long. No doubt they can be as fulfilling and fun as any job in the world.

And of course, the world of amateur astronomy is booming; just pick up the latest issue of Sky & Telescope magazine for evidence.

But the fact remains that for full-fledged professional astronomers, opportunities remain slim.

Why are there so few jobs in astronomy? Chalk it up to federal funding — or, to be more specific, the lack of it.

Traditionally, money for professional astronomy has come from two sources: NASA and the National Science Foundation.

NASA controls most space-based missions, while the National Science Foundation helps fund most ground-based and theoretical research — the realm of traditional astronomy.

According to an online report prepared by the National Academy of Sciences, the NSF astronomy budget has been "severely" decreased over the past few decades at the expense of big-budget space projects.

"Although the number, size and capability of ground-based observing facilities, both public and private, have increased considerably, there has been no commensurate increase in NSF funds for utilizing these facilities," according to another report prepared by the NAS.

Less money for individual researchers, simply put, translates into a paucity of available permanent jobs.

Experiences such as that of Dr. Robert A. Knop are not encouraging for aspiring astronomers.

Knop, who earned a Ph.D. in physics from Caltech in 1997, was an assistant professor of physics and astronomy for six years at Vanderbilt University in Nashville, Tenn.

But earlier this year, he left academia to take a job at San Francisco's Linden Lab, the producers of the online virtual world "Second Life."

His motivation for bailing from astronomy? The inability to gain tenure.

"I've been told directly by my Chair that my tenure case, which would have been submitted in Fall 2008 (after just one more year), had less than a one percent chance of succeeding if I didn't have funding at the level of a [National Science Foundation] grant," Knop wrote this past July on his blog Galactic Interactions.

Nonetheless, Knop is enjoying life after academia.

"I find that I really do feel relieved to be out of the academic politics," he says.

Others in the field find prospects less gloomy. One is Dr. Richard H. Durisen, currently the director of graduate studies in the Department of Astronomy at Indiana University.

"It is true that the job market for what are usually considered the 'best' jobs in astronomy, which tend to be tenure-track positions at [top] universities plus comparable positions at major national labs and observatories, are very competitive," he said. "For those who do not mind going to a more teaching-oriented career, the prospects are not too bad."

He adds: "In the next decade, it could well become a sellers' market for a while as my baby-boom generation retires. This will free up a lot of positions at academic and research institutions of all kinds and levels."

Such rosy predictions have been made before. As late as 1989, the American Astronomical Society was predicting huge shortages of astronomy Ph.D.s for the early to late 1990s. This turned out to be wildly inaccurate.

So where do all the would-be astronomers wind up? In other fields, of course — in business, in computers, in all sorts of positions with a greater promise of a permanent position and a steady paycheck.

How do other fields compare to astronomy in terms of employment outlook? Permanent jobs within the physical sciences are tight, but the picture changes once one goes outside the field.

For example, biomedical and environmental engineering are two areas with "much faster than average" growth, according to the Web site of the U.S. Department of Labor's Bureau of Labor Statistics.

For teachers, "excellent job opportunities" are expected due to an upcoming wave of retirements on the secondary-school level, according to the Department of Labor.

What about personal finance advisers, medical scientists and computer software engineers? All three of these positions are among FastCompany.com's "25 hot jobs for 2005-2009."

Other careers on the rise according to the same list are athletes, marketing managers, lawyers, management analysts and securities sales agents.

Astronomy is nowhere to be found on that list.

So the question suggests itself: What is the long-term effect of job scarcity on astronomy as a field?

Federal funding will remain the most important determinant on the number of astronomy jobs for the near future. In an era of tight budgets, it will remain an option for relatively few.

One sometimes hears the argument that by keeping the professional ranks low in number while keeping a steady supply of freshly minted Ph.D.s, we ensure that only the very best of the best enter the field and thrive once they get there.

But it also ensures a steady supply of workers streaming into other fields who have had their original dreams dashed, and whose aspirations of studying the cosmos have been funneled into other pursuits.

Are we to tell our children that the universe is good for looking at, but that when it comes to choosing a career, it's best to keep one's gaze firmly bound to Earth? In effect, that's what's happening now.

So go ahead, make a wish upon the first star you see tonight — and wish luck upon whoever wants to study it.