exploreYOUR WORLDFIELD NOTE 01 / LIGHT
Speak in oxygen. Write in light.
Solid: simulated sampleDashed: expected mean
Violet hollow circles: stable product.
Make a prediction. Change one thing. See what happens.
FOLLOW THE SCIENCE
The northern lights reveal energy changing hands. Energetic electrons collide with the upper atmosphere and excite its atoms and molecules. Light is released as excited states transition to lower energy states.
The solar wind can transfer energy into Earth’s magnetosphere, where particles are accelerated toward the atmosphere. The aurora is a visible result of that interaction. Explore NASA’s explanation ↗
Want to follow the energy all the way from the Sun? Open Aurora Journey to explore the solar wind, Earth’s magnetic field and spiralling electrons ↗
A FEW QUESTIONS TO TRY
Select oxygen green. Move the excitation slider and watch the wavelength readout. Does it change?
Select oxygen red. Predict whether its photon energy will be larger or smaller than green.
Select the nitrogen ion band. Compare its wavelength and photon energy with both oxygen lines.
The energy carried by one photon equals the difference between the states involved in its emission. A larger energy difference produces a higher-energy photon with a shorter wavelength.
Energy levels shown schematically; spacing is not to scale.
YOUR SELECTED EMISSION
557.7 nm 2.22 eV
E = hc / λ
Change the emission in the experiment to update these values.
The same element has more than one possible transition. Oxygen’s familiar auroral green line is near 557.7 nm; a different transition produces red light near 630.0 nm. Nitrogen has its own emissions, including the molecular nitrogen ion band represented here at 427.8 nm.
Altitude matters too. At greater air density, collisions can interrupt an excited state before it emits. Long-lived oxygen states that produce red light are more likely to radiate in the thinner upper atmosphere. NOAA’s aurora tutorial ↗
For a fixed transition, each photon has the same characteristic energy. Greater brightness can mean more photons are arriving, rather than more energy in each photon. In this illustration, the excitation slider increases visual brightness and particle activity while leaving the selected wavelength unchanged.
Real auroras contain overlapping emissions, varying particle energies and changing atmospheric conditions. The experiment isolates a few relationships so you can explore them.
Energetic electrons arriving along Earth’s magnetic field collide with the upper atmosphere. Excited atoms and molecules release light as they move to lower energy states. Solar-wind interactions supply energy to the magnetosphere; auroral electrons need not come directly from the Sun.
The three selections highlight oxygen at 557.7 nm and 630.0 nm, and a molecular nitrogen ion band at 427.8 nm. The photon energies are calculated from those wavelengths. The nitrogen value represents a band, rather than all nitrogen emissions.
Excitation changes the visual brightness and particle activity. The sky is original imagined artwork. Its slowly moving folds, reflected light, recolouring and particle pulses illustrate the idea. Pause motion freezes the scene; reduced-motion preferences start it paused. They do not model altitude, magnetic geometry, atmospheric chemistry, or a space-weather forecast. Screen colours are approximate.
The pulse chime and ambient sound are a creative sound layer, not recorded auroral acoustics.