The next phase of a global drive to map the night sky will bring the cosmos into greater focus than at any in human history.

Yale University scientists are involved all of the major aspects of the Sloan Digital Sky Survey, an initiative that spans four continents and includes 200 astronomers at more than 40 institutions. They will chart thousands of nearby galaxies, probe the composition of stars throughout the Milky Way with novel clarity, and measure the expansion of the universe during a particularly murky period.

Survey officials announced the fourth phase of the effort on July 15. It will make use of not only the Sloan Foundation 2.5-meter Telescope in New Mexico, but also the 2.5-meter Irenee du Pont Telescope at Las Campanas Observatory in Chile.

“The power of a large survey is that there may be surprises we weren’t planning on, and that means learning something really new,” said C. Megan Urry, Yale’s Israel Munson Professor of Astronomy and Astrophysics and director of the Yale Center for Astronomy and Astrophysics.

“One of the things my group is really excited about is the possibility of getting more information about black holes growing in distant galaxies, including the most luminous ones, known as quasars,” Urry said. “By surveying a very large fraction of the available sky, SDSS IV will greatly increase our knowledge about when and where the most massive black holes grow.”

Yale joined the project four years ago, in its third phase. More than a dozen Yale professors, postdoctoral researchers and students are working with the data, and Yale scientists have written more than 25 papers using survey information.

Already, the survey has registered more than half a million stars in the Milky Way and more than two million galaxies and quasars. The new, fourth phase of the survey broadens the project’s scope and will dramatically expand its database.

This phase has three new components. One will be to create much more detailed maps of nearby galaxies, thanks to an optical fiber bundle technology that takes spectra of each part of a galaxy simultaneously. Another effort will use the Chilean telescope to monitor the makeup and movement of stars throughout the Milky Way that cannot be observed from New Mexico.

The third component will focus on mapping the distribution of galaxies and quasars from 3 to 8 billion years ago. During that period, dark energy began to have an impact on the universe.

“When people ask me what I do I say I’m helping to map the universe,” said John K. Parejko, a postdoctoral research associate at Yale and operations software developer for the sky survey. “It’s not just that we’ll have incredibly more data than ever before, but that the quality and uniformity of the data will be unrivaled for years to come.”

The survey is funded through the Alfred P. Sloan Foundation and other institutions.