Northern lights (Aurora)

When the solar wind dances in the sky

On polar nights, curtains of green, purple and pink dance across the sky — the northern lights! The Sun makes them: particles flying from the Sun crash into Earth's air and make it glow like a lamp. Earth's magnetic field steers them to the poles. Ancient people thought it was spirits dancing. The same happens at the South Pole — the 'southern lights'.

Aurora borealis (northern) and australis (southern) occur when solar-wind particles (electrons, protons), guided to the poles by Earth's magnetosphere, collide with atmospheric atoms at 100–300 km altitude: oxygen glows green (557 nm) and red, nitrogen purple-blue. The auroral oval is a ring at 65–72° latitude around the magnetic pole; Tromsø, Fairbanks and Yellowknife are the best viewing spots. Solar activity follows an 11-year cycle; 2024–2025 is a maximum, and the aurora was even seen from Uzbekistan (May 2024). Strong geomagnetic storms (the 1859 Carrington Event) threaten power grids and satellites. Jupiter and Saturn have auroras too.

Fun facts

• In May 2024 the northern lights were seen even from Uzbekistan — a very rare event!
• The aurora forms 100–300 km up — the International Space Station flies right through it.
• Jupiter and Saturn have auroras too — 1,000 times more powerful than Earth's.