Atlas Eclipticalis was commissioned by the Montreal Festival Society. Like Winter Music, events contain from one to ten notes, divided randomly into two groups. Pitches are notated clearly, though in a somewhat unusual way. The size of the notes, determine their amplitudes. Durations are notated above the events.

Tempo is not given: the conductor determines the duration of each system.

Cage used the Atlas Eclipticalis 1950.0 (an atlas of the stars published in 1958 by Antonín Becvár (1901-1965), a Czech astronomer), superimposing musical staves over the star-charts in this atlas. Brightness of the stars is being translated into the size of the notes in the composition.

In a performance, the score may be played in whole or in part by any number of players up to the full 86 provided.

Atlas Eclipticalis may be performed simultaneously with Winter Music and/or Song Books. Cage also indicated the possibility of attaching contact microphones to some or all of the instruments, thus amplifying their sounds. In this case an assistant to the conductor is required, creating his score using Cartridge Music. Atlas Eclipticalis is the first part of a trilogy of which Variations IV is part 2 and 0’00” is part 3.

Exploring the constellations in the sky of the Canaries in a photograph taken from the peaks of La Palma, and more specifically from a listed natural space called Cumbre Vieja, in July 2008. The title alludes to three very significant stars, visible on summer nights, that form an almost right-angled triangle. Their names are Deneb, Altair and Vega. Each one of them is the brightest star in their respective constellations, namely, Swan, Eagle and Lyre. The image was taken using the astrophotography technique called piggy-back. It consists of a single 30-minute exposure using a Provia 400 film and a Leica reflex camera with a 35mm f2.8 Elmarit lens, opening the diaphragm a point.

The work is located in the civic medieval palace in Padua, known as the Palace of Reason, a building with a plethora of spaces, built, refurbished and added to over the centuries. The work uses interactive digital models to explain the passing of time on manufactured products and their relationship with the heavens. They encompass the whole of the palace as the visitor follows the different strata of information it contains. The digital model of the astrario strikes one as the best introduction to the cultural context that produced the cycle of astrological frescos in the Palace of Reason.