Earth's Heartbeat
How lightning, a thin shell of air and the Sun make our whole planet ring. Free, narrated, with three moments where you take the controls.
Free · about 4 minutes · 3 explore moments · Captions
Best with headphones. Space pauses, arrow keys skip, C toggles captions.
In this lesson
From one flash
to a planet that rings.
- 01Where the signal comes from: about 2,000 thunderstorms at any moment, firing dozens of lightning bolts every second.
- 02The shell between the ground and the ionosphere, and how thin it really is (a millimetre or two on a basketball).
- 03Why a pulse laps the planet in about a seventh of a second, and why only some waves survive.
- 04Where 7.83 comes from: a back of the envelope 7.5, Schumann's 10.6 for a perfect sphere, and the leaky ceiling in between.
- 05How the Sun reshapes that ceiling, shown with the real GOES curve of the X5.4 flare of 7 March 2012.
Explore
The narrator waits.
You take the controls.
Explore 1 of 3
Strike the globe
Tap anywhere on the planet to fire a bolt. Watch its pulse lap the cavity and count the laps.
Explore 2 of 3
Resize the planet
Slide from the Moon to Jupiter and hear the note change, transposed up five octaves so you can hear it.
Explore 3 of 3
Fire the flare
Replay six hours of real X-ray flux in seconds. The ceiling drops, the intensity rises, the frequency barely moves.
Transcript
Every word of the narration.
Storms
Right now, as you listen to this, around two thousand thunderstorms are rolling across our planet. Together, they fire about fifty lightning bolts every single second.
The pulse
Each flash sends out a pulse of energy. Most of it fades away. But some of it gets trapped.
The shell
Between the ground beneath your feet and a layer of charged air high above us, called the ionosphere, there is a gap. A thin shell, wrapped around the whole Earth.
To scale
How thin? The ceiling sits sixty to ninety kilometres up. Against a planet with a radius of six thousand four hundred kilometres, that is about one percent. Shrink Earth to a basketball, and the whole cavity is a millimetre or two thick.
The lap
Energy bouncing inside that shell races around the planet in about a seventh of a second. And when a wave fits perfectly into one lap of the Earth, it meets itself, and grows stronger.
The hum
That is the Schumann resonance. A deep, low hum, close to eight cycles every second, ringing through the entire planet.
Why about eight
Why about eight? Unroll the equator: forty thousand kilometres. The pulse moves at close to the speed of light, three hundred thousand kilometres every second. Divide, and you get about seven and a half laps a second. Schumann's exact math for a perfect sphere lifts that to ten point six. But the real ceiling leaks, and leaks pull the note down. The planet settles at seven point eight.
History
It was predicted on paper in 1952, by a German physicist named Winfried Otto Schumann. In 1960, scientists finally measured it.
The Sun
But the shell is not fixed. When the Sun flares, its radiation reshapes the ceiling of that cavity, and the ring changes with it.
Begin
In this course, we follow that chain. From a single lightning bolt, to the Sun, to what is happening above you right now. Let's begin.
Sources
Where every number comes from.
This lesson makes no claims about effects on people. That question gets its own lesson later in the course, which reports what the studies measured and what is still open.
- NASA Scientific Visualization Studio 10891: about 2,000 thunderstorms at any time, about 50 flashes per second, waves trapped under the ionosphere.
- W. O. Schumann, "Über die strahlungslosen Eigenschwingungen einer leitenden Kugel, die von einer Luftschicht und einer Ionosphärenhülle umgeben ist", Zeitschrift für Naturforschung A 7 (2), 149 to 154 (1952).
- M. Balser and C. A. Wagner, "Observations of Earth to ionosphere cavity resonances", Nature 188, 638 to 641 (1960).
- Ionosphere D region about 60 km by day, about 90 km at night. Earth mean radius 6,371 km, equator 40,075 km.
- Lightning map: NASA LIS/OTD High Resolution Full Climatology v2.3, 1995 to 2013.
- Flare: NOAA GOES 15 XRS, X5.4 peak at 00:24 UTC on 7 March 2012. Flare effects on the resonance: Roldugin et al. 2003, Annales Geophysicae 21.
- Footage: NASA (ISS Earth observation, Solar Dynamics Observatory). Live reading: ResonanceOne pipeline, Tomsk station, hourly.
Up next
Eleven more lessons.
Each one revealed as it opens.
The next one is in production now. All 12 lessons for $19, once, while the founding price lasts.