This is three of the four panels of Halley's Comet. Rick built the head of the comet in the course of one year. 1992 I believe. It's inscribed in the glass. The two center sections in 1994 I think and the final section which was built after this photo was taken, I think it was completed in 1995.
Rick departed from the norm with this piece and included some agates along with the glass. Three of the four pieces hung in the window of the room where he practiced. There wasn't space for all four panels. In fact, you can see part of the miniblind of said window in the upper right. Note that this photo will be replaced later this year with one of better quality and geometry. The new photo will also include the fourth panel. GT