|MadSci Network: Astronomy|
How open is the field for a budding astronomer? Well, not very -- right now the supply of Ph.D. astronomers exceeds the supply of permanent positions (tenured professors and other researchers). A recent article in the Boston Globe cited the unemployment rate among physicists & astronomers at something like 10%. However, if you adjust for the number of people who are taking "temp work" or have taken a job in an unrelated field (finance, consulting, computer industry...), I would guess that something like 50% of Ph.D. astronomers are not able to get the job of their choice (i.e., full-time permanent research in astronomy).
By the time your son gets his Ph.D. and finishes his first postdoc (i.e. in 10-15 years), the job market may have changed somewhat -- Congress may have increased science funding, or the baby-boomer population of astronomers may start retiring en masse. It's hard to predict, but if he has a strong interest in astronomy, and good abilities, it's probably worth trying.
As an undergrad preparing to possibly be an astronomer, he would need to take get a strong foundation in physics, a preparation which would also be very helpful for any number of other jobs or careers should he take a different direction once he graduates from college. In addition to coursework, it's very important to get research experience. He should find an internship or research assistantship at his university, or at a national lab. This would be during the summer before his senior year certainly, and possibly also the summer before that, and during the school year. This research could be either astronomy-related, or completely unrelated, as long as it involves the physical sciences or engineering.
See also this posting for more information about getting an astronomy Ph.D.
Hope this helps!
[Moderator's note: I am a professional astronomer, and I agree with Aaron.
It is very tough to get a job in astronomy right now, but that may
change. To do well at astronomy one also needs a firm background in math and
physics, and be able to program a computer competently. These skills are
also helpful in finding a job in any science related field.
-Phil Plait, Mad Science Astronomy Moderator]
Try the links in the MadSci Library for more information on Astronomy.