The only outdoor work in the Netherlands of American artist James Turrell, 'Celestial Vault' ('Hemels Gewelf', 1996) is a unique observatory inviting you to see the sky as a dome of Dutch light and color. It is also a kind of early scale model of Turrell's major work in progress, Roden Crater.
Commissioned by Stroom, Turrel created a small, grass-sloped crater in the dunes of The Hague (Kijkduin). In the center is a stone bench where two people can lie down with their head tilted slightly backwards. From this position, the rim of the crater frames the sky and the sky appears like a giant dome.
Unfortunately, at the moment the work looks rather shabby from vandalism and neglect. (A sign still claims "persistent drought" as the cause of the bad condition of the grass. Even as another sign cautions visitors to treat the artwork with respect.)
But its idea, so simple, still works. First, it makes the act of observing, which we seldom do exclusively, into an activity. 'Celestial Vault' provides a vantage point (the center of the crater), a posture (lying down on the bench) and a frame (the rim of the crater), all of which contribute to making the observer see more consciously, and more susceptibly.
Second, it makes us see the sky as we would naively depict it, as a dome or vault that covers the earth with us in the middle. A source of inspiration for Turrell, Belgian astronomer Marcel Minnaert described this phenomenon in 'The Nature of Light and Colour in the Open Air' (1937).
When you are outside and look up at the sky, you do not get the impression of a limitless space above you, nor that of a hemisphere hovering above you and the earth. It looks more like a vault whose height above you is much less than the distance between you and the horizon. It is an impression, no more, but to most people a very convincing one; its explanation is psychological and not physical.
A page from Turrell's copy of the book, covered in notes, appears here. And for Dutch speakers, the full text of Minnaert's classic is online: 'De Natuurkunde van 't Vrije Veld. Deel I: Licht en kleur in het landschap'.