Even the most realistic portrait artist, if he's creative, brings a vivid imagination to his studio, along with paints and brushes. The goal of the artist is to look at reality, to form a personal impression of it, and to develop the skills necessary to render the impression in objective terms. The artist is constantly weighing the photographic rendering of reality against the recreation he can construct through his own imagination. And the balance he selects between naturalism and imagination often becomes the artist's identifiable style.
The artist is normally allowed great latitude in his adherence to reality. Yet there is one category of art in which departures from reality oppose the purpose of the art. The purpose is to visualize a part of reality which is "unseeable", and the person who does this is the scientific artist. The two sciences which the scientific artist pursues are paleontology and astronomy. Both sciences need to have their subject matter visualized in realistic, concrete terms--not just laboratory symbols and other mumbo-jumbo.
The astronomical artist of the last few decades had as much to do with the success of the space effort as any technical advance. Just as early American artists showed the public views of the unconquered West and helped propel interest in exploration and expansion (as artists of vision and realistic imagination always point the way), so too, astronomical artists have shown the public what the unseen planets, moons, comets, and distant reaches of the galaxy might look like when we are able to be there in person.
The first space art appeared in 1865 with the illustrations by Emile Bayard and A. de Neuvill for Jules Verne's novel, From the Earth to the Moon. There had been imaginary views of other worlds, and even of space flight before this. But until Verne's book appeared, these views all had been heavily colored by mysticism rather than science. The illustrations accompanying From the Earth to the Moon and its sequel, A Trip Around the Moon, were the first artistic impressions of space ever created strictly according to scientific fact. For these books, Verne even had a lunar map specially drawn by Beer and Maedlerm, the leading selenographers of the day.
In 1874, James Nasmyth and James Carpenter published the classic study of the earth's satellite, The Moon. A large and lavishly illustrated volume, its numerous plates were reproduction of photographs of plaster models of portions of the lunar surface, seen both telescopically from Earth and as they would appear to an observer on the Moon.
During and immediately following the turn of the century, many popular books on astronomy were published and illustrated with space art. The most outstanding illustrator of such books, Lucien Rudaux, was also the first genuine astronomical artist. Rudaux (1874-1947) was both an artist and a professional astronomer. He wrote and illustrated a number of texts, such as the authoritative (and still in print) Larousse Encyclopedia of Astronomy.
Other important artists of the early part of this century are: Scriven Bolton, Abbe Moreux, Howard Russell Butler, Frank R. Paul, Rockwell Kent, and Charles Schneeman. They published their art in many popular journals and newspapers such as The Illustrated London News , Science and Invention, Amazing, Life, Astounding, and National Geographic.
Astronomical art blossomed after the 1950s. In the years immediately before and following the launch of Sputnik I (1957), the space art that appeared in magazines such as Collier's, This Week, and Coronet, and in books , such as The Conquest of Space and Arthur C. Clarke's Exploration of Space (art by Ralph A. Smith), helped convince the public that space exploration was far from a fantasy and that it was well within the reach of contemporary science and engineering. Beyond the question of hardware, realistic and accurate painting of other worlds showed that the moons and planets were not as insubstantial as fuzzy astronomical photographs made them seem, but were genuine worlds in their own right.
Modern space artists have both an easier and, at the same time, more difficult job than the space artists of a generation ago. More discoveries have been made about the nature of our neighboring planets in the last decade than in all the previous history of astronomy. Contemporary artists certainly have more factual material to draw upon, yet this abundance also limits them. We know what the surface of Mars looks like now--there is far less leeway for the artist's own imagination. The phrase "artist's impression" attached to a space painting no longer means an imaginary guess.
From Space Art: Starlog Photo Guidebook, by Ron Miller, 1978. "The Archeology of Space Art".
Wikipedia: The Cosmos contains many sources of visual inspiration that our growing abilities to gather and propagate has spread through the mass culture. Space Art is a general term for art emerging from knowledge and ideas associated with outer space, both as a source of inspiration and as a means for visualizing and promoting space travel. Whatever the stylistic path, the artist is generally attempting to communicate ideas somehow related to space, often including appreciation of the infinite variety and vastness which surrounds us.
Space artists may work closely with space scientists and engineers to help them to visualize and develop their scientific and technological concepts making the dream of space exploration a reality. Other forms of pictorial space art bring the viewer to inner visions inspired directly or otherwise by the fruits of the expanding vision of Humanity. Some aspects of such art pay visual homage to outer space, popular ideas of life on other worlds including alien visitation visions, dream symbology, psychedelic imagery and other influences on contemporary visionary art.
Wikipedia: Space Art