How stars are born from clouds of gas is a rich physics problem whose
solution will inform our understanding of not just stars but also planets,
galaxies, and the universe itself. Star formation is stupendously inefficient.
Take the Milky Way. Our galaxy contains about a billion solar masses of fresh
gas available to form stars-and yet it produces only one solar mass of new
stars a year. Accounting for that inefficiency is one of the biggest challenges
of modern astrophysics. Why should we care about star formation? Because the
process powers the evolution of galaxies and sets the initial conditions for
planet formation and thus, ultimately, for life.Comment: published in Physics Today, cover story, see
http://www.mso.anu.edu.au/~chfeder/pubs/physics_today/physics_today.htm