About this Piece
Tabula siderum zodiaco is an a cappella choral rendition of the celestial map that originates at the ecliptic (the imaginary 24-hour circle that traverses the constellations of the zodiac). Each star of the twelve zodiacal constellations is located at a point above or below this circle of hours. A star’s height or depth above or below the ecliptic determines its pitch in this Tabula, and its placement along the 24-hour ecliptic determines when it occurs rhythmically in this composition.
The entire ecliptic completes a 24-hour day or a 360°-circle. To navigate this circle more easily, I planned this aural map to comprise 120 measures of 3/4 meter, or 360 quarter-note beats. Therefore, each quarter note represents 1° of the completed circle, or 4 minutes of the celestial day. In this piece, rhythmic placement of every star has been computed to the nearest quarter-note beat; the first pitches are the earliest stars of the first constellation (Aries), and the latest stars found in Pisces (the last sign) are prolonged to make up the closing sonority of the piece. The pitches of this composition have been chosen to reflect the relationship between the twelve signs (or “houses”) that are embraced by the ecliptic, and the twelve keys in the circle of fifths. First, pitches of the entire chromatic gamut were assigned all of these stars (from D#2 to B5) according to their height of depth above or below the ecliptic (at middle C4). Then, the pitch of each star was “rounded” to the nearest diatonic pitch.
In this composition, the duration of each star’s pitch is directly related to its measure of brightness, or magnitude. Within this collection of 928 stars, magnitudes between 0.85 to 6.74 have been inversely interpolated, so that the brightest stars have been assigned a duration of 6 beats and the dimmest stars (which are, by the way, far too faint to be seen with the naked eye) are to be sung for the duration of a single quarter note.
The text of this Tabula is derived from the ancient bipartite name for each star: a Greek letter (in majuscule letters in the score), followed by the Latin genitive of the constellation’s name (listed in the table above). In ancient celestial maps, the 24 letters of the Greek alphabet were assigned according to brightness, so that Alpha Arietis would be the brightest star in Aries, Beta Aquarii was the second brightest in Aquarius, and Omega Piscium the dimmest star visible in Pisces.
In the modern era, the stars that are dimmer than the Omega of each constellation have been named with numbers (as in 55 Cancri). In this composition however, I felt that singing a bunch of numbers would be going a bit too far! For the 333 stars that are bright enough to have been named with Greek letters, I have assigned them to be sung. As for the text of the 595 dimmer stars (those named with numbers), I have scripted that the syllables of each star’s second name (its Latin genitive form, in miniscule letters in the score) be sung slowly, over the 30 beats of each zodiacal house, on each of the diatonic pitches and in all of the choral voices that embrace the stars of each constellation.