See the Northern Lights Tonight? What Auroras Are and What the Colors Mean

See the northern lights tonight? Here's what you need to know

Nearly two dozen U.S. states had a chance to see the northern lights on Nov. 12, and the aurora may return tonight for viewers under clear, dark skies. The dramatic light shows are not just beautiful — they are a visible reminder of how the Sun and Earth interact.

What are auroras?

Auroras are glowing curtains, arcs or patches of light that appear in high-latitude skies. When this phenomenon appears in the Northern Hemisphere it is commonly called the northern lights or aurora borealis; in the Southern Hemisphere it is the southern lights or aurora australis. They most often occur near Earth’s magnetic poles.

How auroras form

The Sun emits a continuous stream of charged particles (the solar wind) and occasionally larger disturbances called solar storms or coronal mass ejections (CMEs). When these particles reach Earth, they interact with and disturb the planet’s magnetic field. Charged particles are guided along magnetic field lines toward the polar regions, where they collide with atoms and molecules in the upper atmosphere. Those collisions transfer energy to the atmospheric gases and cause them to emit light — the aurora.

Why auroras show different colors

The color of an aurora depends on which atmospheric gas is struck and the altitude of the collision. Different atoms and molecules emit characteristic wavelengths of light when excited. Emissions from different species and heights can overlap, creating blended colors.

Common colors and what they mean

• Green — The most common color seen from the ground. Produced by collisions with oxygen atoms at roughly 100–300 km altitude.
• Red — A deeper red comes from oxygen atoms at higher altitudes, typically around 300–400 km.
• Pink or dark red — Often seen at the lower edge of an auroral curtain; produced by excited nitrogen around ~100 km.
• Blue and purple — Caused by molecular nitrogen or ionized nitrogen (and in rare cases hydrogen/helium) at lower altitudes (roughly 100–200 km); mixing with oxygen emissions can yield violet or white tones.

When and where to look

Auroras are most likely when geomagnetic activity is elevated after a CME or strong solar wind stream. For best viewing: find a dark site away from city lights, face north (in the Northern Hemisphere), and watch during local night hours. Keep an eye on space-weather forecasts from NOAA/Space Weather Prediction Center or apps and sites like SpaceWeatherLive for real-time chances and viewing maps.

Practical tips for watching and photographing

Give your eyes 20–30 minutes to adapt to the dark. Use a tripod and a camera with manual exposure settings for photos (wide aperture, ISO 800–3200 depending on conditions, and exposures of a few seconds). Dress warmly and be patient — auroras can appear suddenly and change rapidly.

In short: Auroras are caused by charged solar particles striking oxygen and nitrogen in Earth’s upper atmosphere along magnetic field lines. The specific gases and altitudes involved determine the colors you see.