He has written many technical articles and a series of popular science books including The Living Cosmos, How It Began, How It Ends: From You to the Universe, Dreams of Other Worlds, and Humble Before the Void.
His early work was on the sub-class of active galactic nuclei called BL Lac objects, now thought to be highly luminous and variable extragalactic sources where our sightline looks nearly down the spin axis of a supermassive black hole emitting twin relativistic jets.
As a postdoc at Caltech he worked with Greg Bothun at the University of Oregon on the properties of dim and diffuse stellar systems that tend to be missing from most galaxy surveys.
At Steward Observatory in the 1990s, he studied the intergalactic medium using multiple quasars to probe the three dimensional structure of the hot, diffuse gas in galaxies,[6] which contains as many baryons as the sum of all the stars in the universe.
He was the lead author of the University of Arizona plan for instructional computing in the 1990s and he gave the first invited education talk at an American Astronomical Society meeting.
[10] Impey has written a number of popular science books, marked by their incorporation of cutting edge research, and the use of vignettes that place the reader in unfamiliar scenes.
The Living Cosmos (2007) is a survey of the emerging field of astrobiology, published initially by Random House and in 2011 republished by Cambridge University Press.
With planetary scientist Bill Hartmann he wrote two introductory textbooks for college-level astronomy, The Cosmic Journey (1994) and The Universe Revealed (2000).
With English professor Holly Henry he has written a survey of the scientific and cultural impact of iconic NASA missions in Dreams of Other Worlds (2013).
His most recent book, Humble Before the Void (2014), based on teaching cosmology to Tibetan Buddhists in India as part of the Science for Monks program.