Imagine you are laying on the floor of the Guggenheim rotunda and that you are looking up at James Turrell’s new work. This is what you’d see.

The colors slowly, slowly morph for the next hour, changing from pink to green to yellow until they work through the entire color cycle. As yellow fades, you see the white, glowing sun…or is it the moon?

Aten Reign moment in the Guggenheim atrium, James Turrell’s site-specific spectacular. Source: Guggenheim

You need to get there to experience the spectacular light before September 25, when James Turrell takes his leave of New York, the end of his first major show here. The museum’s exhibition site is wonderful, but it’s no match for the out-of-this-world, cosmic experience of his masterful Aten Reign.

The Guggenheim has blocked off the famous skylight and any view of the atrium from its gallery spiral. Viewing the light show from the ground floor, all viewers see are these rings of slowly changing light with an oval center – a natural shape that Mr. Turrell loves.

Out-of-towners expecting to have the fun of walking up the ramp and looking down on ever-tinier ground-floor visitors will be disappointed. But other magical Turrell encounters await.

On Level 2, we found celebrated security guard, Jeffrey Martinez (see this week’s New York Times profile on him) holding throngs in rapt attention explaining the magic wrought by Mr. Turrell with his corner floor-to-ceiling strip of light. Martinez told us that although it appeared to be a vertical “light”, we were actually seeing an illumination emanating from behind the false wall. The New York Times was right to single him out for a story, because it felt like we were meeting a celebrity with art-world smarts, gently cautioning people against trying to touch and asking them to “stand back” to give the piece some space.

Afrum I (White), 1967, one of Mr. Turrell’s early cross-corner projections. Source: Guggenheim

Upstairs, the show presents two more light installations that mimic two of the twenty 2D etchings precisely ringing a small gallery. Mr. Turrell creates the illusion, on paper, of light glowing from the white cubes surrounded by the ink. You just have to see them and then turn the corner to see “square” beams of light illuminating two walls. In the second room, Afrum I (White) astounds. You think you’re seeing a levitating white cube of light. Magical.

Hear him talk about his view of Mr. Wright’s philosophy and building and why they are so right for one another:

Enough said. Go see it.

Spoiler alert: The Guggenheim’s YouTube site has several videos about how Turrell and the team created the magic on the spiral.