The Wall Street Journal has compiled a graphic displaying unemployment rate and median income based on college major. The data was taken from the Georgetown Center on Education and the Workforce.
From the data we find astronomy and astrophysics was among (several) majors with the lowest unemployment rate: 0.0 percent. The median salary for Astro was $60,000, placing it somewhere between counseling psychology ($34K) and Petroleum Engineering ($127K) among all fields listed.
Unemployment rate measures the ratio of people currently, actively seeking employment and unable to find it to the entire labor force. It does not include under-employment and those who have given up searching.
Topping the list with 0.0 percent were actuarial science (math and statistics for risk assessment in finance), pharmacology, education administration, school student counseling, geological and geophysical engineering, and astro. At the bottom of the list was Clinical Psychology with 19.5 percent unemployment, proving people will pay you to talk to them about the stars, but not their own shortcomings.
The handy graphic can be found on the Journal's website, or through some discussion over at Yahoo! News.