Space art, also known as astronomical art, is a genre of modern artistic expression that uses the universe as a frame of reference. Like other genres, space art has many facets and encompasses realism, impressionism, hardware art, sculpture, abstract imagery, and zoological art. Though artists have long produced work with astronomical elements, the genre of space art itself is still in its infancy, having begun when technological advancement allowed for more detailed observation of the night sky. Regardless of style, space art attempts to communicate ideas related to space, often including artistic interpretations of cosmological phenomena and scientific discoveries. In some cases, artists who consider themselves space artists use more than illustration and painting to communicate astronomy, working directly with spaceflight technology and scientists to expand the arts, humanities, and cultural expression related to space exploration. Practitioners of the visual arts have for many decades explored space using traditional painting media, with a recent shift toward digital media. Science fiction and picture-essay magazines were once major outlets for space art, often featuring planets, spaceships, and dramatic alien landscapes. Notable artists include Chesley Bonestell, R. A. Smith, and Lucien Rudaux. Hardy and Ludek Pesek were among the major artists in the early days of the genre. They were actively involved in visualizing space-exploration proposals, working with astronomers and experts in the infant rocketry field to spread ideas to a wider audience. NASA's second administrator, James E. Webb, initiated the agency's space art program in 1962, four years after NASA's founding. Chesley Bonestell in particular portrayed exotic worlds with their own alien beauty, often emphasizing the destination as much as the technological means of getting there. Astronomical art, an aspect of space art devoted to visualizing outer space, places major emphasis on the space environment as a new frontier for humanity. Many works portray alien worlds, extremes of matter such as black holes, and concepts inspired by astronomy. Largely pioneered in the 1940s and 1950s by Bonestell, astronomical art benefited from his ability to solve perspective problems, paint with the eye of a matte artist, and consult experts in the fields that fascinated him. His work helped inspire many in the post-war era to think about space travel, which had seemed fantastical before the V-2 rocket. Today, artists continue to help turn ideas into visible forms for the space community, portraying both methods of leaving Earth and what may exist in space. Astronomical art is the most recent of several art movements that explore ideas arising from the ongoing exploration of Earth (Hudson River School, Luminism), the distant past (ancient history and prehistoric animal art), and the steadily revealed universe. Most astronomical artists use traditional painting methods or digital equivalents to bring viewers to the frontiers of knowledge revealed by space exploration. They typically employ realism extrapolated to exotic environments, with details informed by current science and educated conjecture.

For example, an artist might study and visit desert landscapes to approximate what Mars feels like and paint from those experiences, or learn of an intriguing phenomenon and consult scientific articles or experts. Artists usually emphasize the most visually compelling elements, much like a photographer composes a shot. The best astronomical art conveys what originally captivated the artist. In the 1950s, science fiction magazines—Fantasy and Science Fiction, Amazing, Astounding (later renamed Analog), and Galaxy—served as major outlets for space and astronomical art. The picture-essay magazines of the time, such as Life, Collier's, and Coronet, were major outlets for this art. Today astronomical art appears in publications like Sky & Telescope, The Planetary Report, and occasionally Scientific American. The NASA Fine Arts Program hires professional artists to create works that document historical events related to specific space projects; it began under James Dean during an era of seemingly limitless progress, although pictorial realism was only one of several visual influences. Works that document spaceflight are similar in concept to government efforts during World War II to send artists to battle zones, much of which appeared in Life. A close parallel to astronomical art is dinosaur art: both genres explore unreachable realms while striving to convey a sense of reality. The grand masters of that field, such as Charles R. Knight and Zdeněk Burian, worked with experts and used the best available information to create realistic visions of things we can never behold with our own eyes. Ideally, as in astronomical art, such work shows what is known about its subject, using educated guesses to fill in the unknown. Many recent pieces by leading dinosaur artists reflect advances in understanding of posture, likely feathers, and so on, just as modern alien landscapes are painted to reflect accumulated knowledge rather than the craggy fantasies and "blue-sky" Mars of earlier eras.