Not only does Harris's art spur the imagination; it also conveys a sense of great size and distance. This theme runs through many of his works, and lent the title to a series of paintings known as Mass.
While this project never saw printed form, many of the paintings (as well as illustrations from his many other projects over the years) appeared in the art collection Mass: The Art of John Harris. I was fortunate enough to stumble across several years ago; the paintings are even better on the printed page. Unfortunately, the only print collection of his works is out of print. As noted in the link above, however, Mass can be found used on Amazon.
For more on Harris, see this article on Astrona Space and Astronomical Art Journal.