Only 20 per cent of PhD students in astronomy will manage to secure jobs in their field, according to a new report.
An investigation by the Royal Astronomical Society found that while it is easy for qualified students to find a place to do a PhD in astronomy, the vast majority discover when they finish their theses that they are unable to pursue careers as astronomers. Nearly 80 per cent will end up working outside their specialism.
The society also found that many of the lucky ones who are able to find academic positions in astronomy after their PhDs have to move abroad to do so.
Robert Smith, chairman of the society's membership committee, said: "There has been a genuine feeling of frustration from PhD students because the career structure is less than satisfactory."
The report warns that if the Particle Physics and Astronomy Research Council goes ahead with plans to substantially increase the number of PhD studentships it funds - possibly by as much as 50 per cent - the problem could be intensified.
The society fears that without funding more postdoctoral positions there will be nowhere for many of the new cohort to go in academia.
The report points out that "frustrated" and "embittered" young astronomy researchers will not serve UK science well.
Dr Smith, who is a reader in astronomy at Sussex University, said: "Some increase would be OK, but we would be unhappy if there really were a 50 per cent increase because that would reduce the career prospects for students so much."
The report suggests that astronomy could be a more general qualification, with transferable skills such as a strong understanding of information technology. But it says that this is a point that employers and students often overlook.
Former astronomy PhD students include Ene Ergma, the president of the Estonian Parliament, and senior civil servants in the UK's Department of Trade and Industry.
Philip Diamond, assistant director of higher education at the Institute of Physics, said that most physics departments now incorporated astronomy. But he said that the lack of career structure was a problem across the physics field, as well as in disciplines outside science.
He said: "We have looked into the situation for postdocs. We discovered that there is a need for more general awareness of the competition for academic posts. People who embark on PhDs or postdocs should not go into it assuming that they will become researchers."
He added that university departments had a tendency to persuade students to take on a PhD without thinking through the consequences.
'You're not even paid for the lack of job security'
Robbie Auld knows how important it is to be passionate about your subject.
Auld, who is in the final stages of a PhD in astronomy at Cardiff University, has just started applying for postdoctoral positions in order to continue his astronomy career.
The crunch time for early-career scientists comes when they try to find a permanent university post.
"It's quite hard to find a permanent position in astronomy. It's common to see six-month contracts for lectureships," Auld said.
There's little job security and, he points out, "you're not even paid for the lack of job security".
But for young scientists such as Auld money is not a deciding factor in the job search.
Like many other early-career academics, Auld faces the "two-body problem" - his girlfriend is also about to complete a PhD in astronomy.
"It will be hard to find two postdoctoral positions at the same university," he suggested.
For this reason, he applauds the concept of "virtual universities" such as the Carolune Institute for Quality Astronomy (CIQuA), a web-based astronomy institute, which he sees as a possible solution to the two-body problem.
Its fellows do not have to live in a fixed location, which suits astronomers very well. Auld said: "We take pretty pictures and can analyse them anywhere."
So far, he has relied on his own initiative and on word of mouth to track down opportunities.
He's no stranger to job hunting - he worked in the IT industry for several years after completing a degree in astronomy and astrophysics.
Balancing writing up his PhD thesis with applying for jobs can be daunting, he admitted, but he knows what he wants and he believes that his passion for his subject should help him find a postdoctoral position.
Yfke van Bergen