collapse, drawing in even more material. The temperature rises, the region becomes even denser—until boom, a star is born. 
    This process occurs tremendously fast in the Rho Oph dark cloud but, because of dust and gas, much of it is invisible at optical wavelengths. The densest region, the dark patch just below and to the left of Rho Oph, has been studied extensively in millimeter and infrared wavelengths. It is estimated that the core of this region, with a volume less than 30 cubic light years, contains 600 times the Sun’s mass, not counting dust or stars. Spanning virtually the entire region depicted in this image, the rest of the Rho Oph cloud contains gas clouds totaling approximately 10,000  solar masses.