The Turning Sky
“When the morning stars sang together, and all the sons of God shouted for joy?”
Job 38:7 · King James Version
As the Earth spins, the whole sky turns around the celestial pole once every 23 hours 56 minutes, like a record on a turntable. Here a needle rests on that turning sky, and every real star plays a note as it passes beneath it, leaving a trail of light like a long-exposure photograph.
How to listen
- Put on headphones. Phone speakers work, but the low notes near the pole and the reverb come through much better with headphones.
- Choose a sky. Pick the hemisphere you live under, or the one you have never seen.
- Drop the needle. Press the button on the record to start the sky turning. On phones, sound starts only after you tap.
- Northern · Bagpipes · brightness 3.5Watch the stars above Orion. Menkalinan, Mahasim, Propus, Mirzam and Tejat cross in turn and play the opening notes of Amazing Grace.
- Southern · HarpThe Southern Cross and the two Pointers, Alpha and Beta Centauri, cross within about ten seconds of each other in a bright run of notes.
- Either · Acoustic guitar · Snap to beatThe stars fall into a steady rhythm and it starts to sound like someone playing.
- Either · Soft pad · exposure 12 hSlow the turntable right down for long, overlapping swells and deep star trails.
How the stars become music
Pitch is the groove
Each star circles the pole in its own groove. Stars near the pole play low notes, and stars near the celestial equator play high notes. The pole star rings once per turn as the lowest note.
Tone is colour
Hot blue-white stars ring clear and bright. Cool orange and red giants sound softer and warmer. The colour comes from each star's measured B–V colour index.
Loudness is brightness
Brighter stars play louder and longer. Each record lets you choose how faint a star can be and still play, from only the brightest to nearly two thousand.
From the sky
A day of 23 h 56 m
The stars return to the same place four minutes earlier each night. That shorter day, measured by the stars, is called a sidereal day, and it sets the speed of the record.
Polaris is a little off-centre
The North Star sits slightly away from the true pole, so it traces a tiny circle of its own. Watch for it near the centre of the northern record.
The pole is moving
Earth's axis wobbles slowly, like a spinning top. In about 12,000 years the pole will point near Vega, and the northern record will turn around a new star.
About
My name is Matthew Turner, and I love discovering things and creating. One morning I woke up thinking about the sky's steady turning, and I wondered: has anyone ever taken a long-exposure photograph of the night sky and played it like a record?
It turns out people have made music from the turning sky before, as a celestial music box and as a star clock. But as far as I know, no one had played the stars like a record, with the pole as the spindle and every star in its own groove. So here it is.
I hope it helps you see the beauty of creation.
— Matthew Turner
The Turning Sky is free, with no ads or sign-ups. If it gave you a moment of wonder, you can help keep the sky turning.
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