As 800 astronomers from around the globe converge on campus for the 40th annual meeting of the American Astronomical Society's Division of Planetary Sciences (DPS), musicians from Cornell and Ithaca College are preparing for their own astronomical performance.

On Oct. 11 in Bailey Hall, they will take on Gustav Holst's seven-movement orchestral suite "The Planets," first performed in 1918; and premiere a piece by Cornell composer Roberto Sierra titled "Anillos," or "Rings," inspired by images of Saturn from NASA's Cassini mission.

The performance will be the culmination of an idea that started small, but took on a life of its own over two years of planning.

"'The Planets' is one of those pieces I've been wanting to do for a long, long time," said Chris Kim, Cornell orchestra director.

In 2006, Kim asked Jim Bell, associate professor of astronomy, if he might contribute images of the planets to accompany the piece. Bell agreed, and suggested the performance be linked to this week's DPS meeting.

To create a visual backdrop for the music, astronomy graduate students -- including Laura Spitler, who is also principal bass player for the orchestra -- and postdoctoral researchers Matthew Hedman and Matthew Tiscareno spent hours listening to a recording of Holst's orchestral suite. They sifted through archival images of each planet, piecing together a slide show perfectly timed to each movement.

In meticulous notes, they explained their choice of each image: Mercury shown against the Sun to complement the musical dissonance of "Mercury"; mysterious, ethereal views of Neptune and its moon Triton to accompany the mystical tones of the final movement.

"I was astounded at how musical all the students were who were putting together the slide show," said Kim. "They put in countless hours -- they really wanted to get it right. And the quality of images we had access to is unbelievable."

It was Elizabeth Bilson, retired administrative director for Cornell's Center for Radiophysics and Space Research, who, while helping to plan the concert last year, proposed an original musical piece for the conference.

Bilson had worked with astronomy professor Joe Burns on the American Museum of Natural History's exhibit of images from the Cassini mission, and she wondered if those ethereal images of Saturn and its rings and moons, which she described as "sheer aesthetic pleasure," might also inspire a work of music.

She floated the idea to composer Sierra, the Old Dominion Foundation Professor in the Humanities.

"I thought he would laugh at me," Bilson confessed. Instead, Sierra took the challenge. With a selection of images from the Cassini mission and essays by 17th-century astronomer and musician Christiaan Huygens as his guide, Sierra composed the 10-minute-long, full-orchestra piece "Anillos."

"The way I shaped the piece was to reflect the sort of circular motion of the rings," Sierra said -- beginning it at the middle of the register, then guiding the instruments in a sweeping, looping cycle, and including a percussion solo with 20 instruments by music lecturer and percussionist Tim Feeney.

The Cornell Symphony Orchestra will open Saturday's concert with a premiere of the piece, which will be followed by a full-scale, true-to-the-score performance of "The Planets," by a combined orchestra of 224 Cornell and Ithaca College students. The concert will be accompanied by the slide show, and -- at the end -- by a women's choir offstage. Guest conductor Jeffery Meyer of Ithaca College will lead the first three movements; orchestra director Kim will conduct the last four.

"In all aspects this is a dream case scenario of what a classical concert should be," Kim said. "It explored an old piece, but with a new perspective, a new element -- and a brand new piece that has never been heard before."