Where can you see the northern lights in the United States?

In the continental United States, the northern lights are most often seen in northern states (Alaska, Maine, Michigan, Minnesota, North Dakota, Montana, Washington) during geomagnetic storms of Kp 5+. During severe storms (Kp 7-8), they become visible in mid-latitude states like New York, Pennsylvania, Iowa, and Oregon. During extreme events (Kp 8-9, like the night of May 10-11, 2024), auroras have been visible as far south as Texas, Florida, and California. Ideal conditions: clear sky, away from light pollution, with an unobstructed northern horizon.

How can you forecast an aurora?

Watch the NOAA SWPC (Space Weather Prediction Center) site, which publishes Kp forecasts at 30 minutes, 3 days, and 27 days. Solar flares (M and X class) and coronal mass ejections (CMEs) signal geomagnetic activity 1 to 3 days later. Recommended apps: SpaceWeatherLive, My Aurora Forecast, Aurora Pro. The Vigi-Sky app sends alerts on favorable Kp 5+ episodes.

What is the aurora borealis?

Q: What is the aurora borealis?

The aurora borealis is a luminous phenomenon caused by energetic solar particles (electrons and protons) colliding with molecules in Earth's upper atmosphere near the magnetic poles. The dominant green comes from atomic oxygen at 100-150 km altitude, deep red from oxygen at 200-300 km, and violet/blue from ionized molecular nitrogen. The phenomenon is produced by the interaction between the solar wind and Earth's magnetic field.

Q: What is the difference between the aurora borealis and the aurora australis?

The two phenomena are physically identical. The difference is purely geographic: the aurora borealis (northern lights) occurs in the Northern Hemisphere, around the north magnetic pole (Norway, Iceland, Canada, Alaska). The aurora australis (southern lights) occurs in the Southern Hemisphere, around the south magnetic pole (Antarctica, southern Australia, New Zealand, Tasmania, Patagonia). They often occur simultaneously as mirror images.

Q: What is the Kp index?

The Kp index (planetary K-index) is a 0-to-9 scale that measures Earth's geomagnetic activity, updated every 3 hours by NOAA SWPC. Kp 0-3 means quiet conditions, Kp 4 means auroras visible at high latitudes, Kp 5-6 (minor G1-G2 storm) means auroras possible in Scotland, Belgium, and northern Europe. Kp 7-8 (severe G3-G4 storm) means auroras potentially visible across the continental United States and central Europe. Kp 9 (extreme G5 storm) means auroras visible as far south as the Mediterranean, a rare event (May 2024).

Q: When is the best time of year to see the northern lights?

Auroras are more frequent near the equinoxes (March and September-October) due to the Russell-McPherron effect, which favors magnetic connection between the Sun and Earth. The viewing season runs from October to March in the Northern Hemisphere (long nights are required). The current solar maximum (cycle 25, peak 2024-2025) significantly increases probabilities through 2027-2028.

Q: How do you photograph the aurora borealis?

Use a camera in manual mode on a tripod: ISO 800-3200, widest aperture (f/1.4 to f/2.8), exposure of 5 to 25 seconds depending on intensity, manual focus to infinity, wide-angle lens (14-24 mm). RAW format is essential. Modern smartphones (iPhone 13+, Pixel 6+, Samsung S22+) in night mode can now capture auroras invisible to the naked eye thanks to highly sensitive sensors and AI image fusion.

Q: Are the northern lights dangerous to your health?

No, absolutely no danger to human health. Energetic solar particles are deflected and slowed by the magnetosphere and atmosphere. Auroras occur at 100-300 km altitude, well above commercial airliners (10-12 km). However, strong geomagnetic storms can disrupt HF radio communications, GPS, low-orbit satellites, and exceptionally power grids (the Quebec blackout of March 1989).

Q: What is the link between solar flares and auroras?

Solar flares emit bursts of electromagnetic radiation that reach Earth in 8 minutes. Coronal mass ejections (CMEs) are projections of magnetized plasma that take 1 to 3 days to reach Earth. When a CME strikes Earth's magnetosphere with a southward-oriented magnetic field (negative Bz), it triggers a geomagnetic storm and therefore auroras at lower latitudes.

Q: Are there auroras on other planets?

Yes, auroras exist on every planet with a magnetic field and an atmosphere. Jupiter has permanent ultraviolet auroras a thousand times more powerful than Earth's (observed by Hubble and Juno). Saturn, Uranus, and Neptune have them too. Mars has lost its global magnetic field but still hosts diffuse auroras. Venus and Mercury have faint auroras. Even magnetized exoplanets produce them (LOFAR radio detections).

The physics, the colors (green, red, purple), the Kp index, viewing from mid-latitudes, photography, forecasting, and the link to solar flares — everything you need to know about the northern lights.

TL;DR — Quick answer

The aurora borealis (or northern lights) is a luminous phenomenon caused by energetic solar particles (electrons, protons) colliding with Earth's atmosphere near the magnetic poles. The dominant green comes from oxygen at 100 km, red from oxygen at 200-300 km, and violet/blue from molecular nitrogen. Auroras occur when the solar wind disturbs Earth's magnetosphere.

Vigi-Sky Team · May 3, 2026 · 10 min read · Space weather

What is the difference between the aurora borealis and the aurora australis?

The two phenomena are physically identical. The difference is purely geographic:

Aurora borealis (northern lights): Northern Hemisphere, around the north magnetic pole. Visible from Norway, Iceland, Finland, Canada, Alaska, and Siberia. During strong geomagnetic storms, it extends down to mid-latitudes (continental United States, central Europe).
Aurora australis (southern lights): Southern Hemisphere, around the south magnetic pole. Visible from Antarctica, Tasmania, New Zealand, and southern Chile and Argentina. Exceptionally extends as far as southern Australia or South Africa.
Magnetic symmetry: The northern and southern lights often occur simultaneously as mirror images, fed by the same flow of solar particles guided by Earth's magnetic field lines.

What is the Kp index and how do you read it?

The Kp index (planetary K-index) is the international standard scale measuring Earth's geomagnetic activity. Updated every 3 hours by NOAA SWPC (Space Weather Prediction Center), it ranges from 0 (quiet) to 9 (extreme).

Kp index	NOAA level	Aurora visibility
Kp 0-3	Quiet	Polar circle only
Kp 4	Active	High latitudes (Norway, northern Canada)
Kp 5	G1 (minor)	Scotland, Norway, central Sweden, northern US states
Kp 6	G2 (moderate)	Belgium, northern Germany, Denmark, US Midwest
Kp 7	G3 (strong)	Northern France, mid-latitude US states
Kp 8	G4 (severe)	Most of continental Europe and US
Kp 9	G5 (extreme)	Mediterranean, Spain, Italy, Texas, Florida

Where can you see the northern lights?

The northern lights have long been considered rare in mid-latitude regions. The current solar maximum (cycle 25, peak 2024-2025) has changed that picture:

Northern regions (Alaska, Canadian provinces, Scandinavia, northern UK, northern US states like Maine, Michigan, Minnesota, North Dakota): visible from Kp 5-6, several times per year during solar maximum.
Mid-latitude regions (central US, central Europe, southern UK): visible from Kp 7-8.
Southern latitudes (Texas, Florida, southern France, Spain, Italy): rare, requires Kp 8-9. Spectacular events on May 10-11, 2024 (G5) and October 10-11, 2024 (G4).

Optimal conditions: perfectly clear sky, away from urban light pollution, with an unobstructed northern horizon (mountains, ocean, or open plains). A full moon significantly reduces visibility.

When is the best time of year to see the northern lights?

Two annual statistical peaks are well established: the spring equinox (March) and the autumn equinox (September-October). This phenomenon, called the Russell-McPherron effect, is explained by the optimal geometric alignment between the solar magnetic field and Earth's magnetic field at the equinoxes.

The winter viewing window (October to March in the Northern Hemisphere) is favored for a practical reason: nights need to be long enough. North of the Arctic Circle, continuous polar night allows 24/7 viewing.

Solar cycle 25

The maximum of solar cycle 25 (peak forecast for mid-2025) has already produced several G4-G5 storms. High activity should persist through 2027-2028, offering exceptional viewing opportunities at mid-latitudes.

How do you forecast an aurora?

Space weather is now as predictable as terrestrial weather, with 1-3 days of lead time. The tools:

NOAA SWPC (swpc.noaa.gov): the global reference. Forecasts at 30 min, 3 days, and 27 days.
SOHO and SDO: NASA/ESA solar observatories that detect flares and CMEs in real time.
Mobile apps: SpaceWeatherLive, My Aurora Forecast, Aurora Pro, Hello Aurora.
Vigi-Sky: Kp 5+ alerts and correlation with citizen observations.

The typical storm sequence: solar flare (X-class) → 8 minutes later, X-ray impact → 1 to 3 days later, arrival of the CME (coronal mass ejection) → geomagnetic storm → auroras.

How do you photograph the aurora borealis?

Aurora photography has become accessible thanks to modern sensors. Recommended settings:

DSLR / Mirrorless (manual mode required): ISO 800-3200, widest aperture (f/1.4 to f/2.8), 5-25 second exposure, manual focus to infinity, wide-angle lens (14-24 mm), RAW format, tripod essential, cable release or 2-second self-timer.
Modern smartphone (iPhone 13+, Pixel 6+, Samsung S22+): Enable Night Mode. Stabilize the phone (tripod or against a wall). Automatic 3-30 second exposure depending on brightness. Disable the flash. Recent sensors and AI fusion often reveal auroras invisible to the naked eye.
Universal tips: Arrive on site 30 minutes early to adapt your night vision. Avoid white screens (use red mode). Wear very warm clothes (the best auroras come at -10°F!). Bring a spare battery (cold cuts battery life in half).

Are the northern lights dangerous to your health?

No, no danger to human health. Energetic solar particles are deflected and slowed by Earth's magnetosphere, then absorbed by the upper atmosphere. Auroras occur at 100-300 km altitude, well above commercial airliners (10-12 km).

Strong geomagnetic storms can, however, disrupt:

HF radio communications (aviation, marine).
GPS (temporary positioning errors).
Low-orbit satellites (increased atmospheric drag).
Exceptionally, terrestrial power grids (Quebec blackout in March 1989, a 9-hour outage affecting 6 million people).

What is the link between solar flares and auroras?

Three types of solar events feed auroras:

Solar flare: Intense burst of electromagnetic radiation (X-rays, UV). Reaches Earth in 8 minutes. Classes A, B, C, M, X (X being the strongest). Causes radio blackouts but few direct auroras.
Coronal mass ejection (CME): Massive projection of magnetized plasma (up to 10 billion tons). Travels at 300-3000 km/s, reaches Earth in 1 to 3 days. The main cause of intense auroras.
Coronal hole and high-speed solar wind: Dark regions of the solar corona that emit a continuous solar wind (700-800 km/s). Causes recurring auroras every 27 days (solar rotation).

Key criterion: when the CME's magnetic field arrives with a southward orientation (negative Bz), it reconnects with Earth's field and triggers a major geomagnetic storm.

Are there auroras on other planets?

Yes, auroras exist on every planet with a magnetic field and an atmosphere:

Jupiter: permanent ultraviolet auroras a thousand times more powerful than Earth's. Observed by Hubble, Juno (NASA probe in orbit since 2016), and previously Cassini.
Saturn: UV and infrared auroras, photographed by Cassini.
Uranus and Neptune: faint but detected auroras, by Voyager 2 and later Hubble.
Mars: lost its global magnetic field but still has diffuse auroras (MAVEN mission, 2014-).
Venus and Mercury: faint auroras despite the absence of a global magnetic field.
Exoplanets: radio signatures detected by LOFAR and SKA on brown dwarfs and magnetized exoplanets.

What are the cultural myths surrounding the aurora?

Auroras have fascinated every polar culture:

Vikings (medieval Scandinavia): The reflection of the Valkyries' armor, guiding fallen warriors to Valhalla. Source: Icelandic sagas (13th century).
Inuit (Greenland, Arctic Canada): Spirits of the dead playing ball with walrus skulls. Whistling at the lights dangerously attracts them.
Sami (Lapland): A sacred phenomenon to respect in silence. Noise brings misfortune.
Traditional Japan: Seeing an aurora promises marital happiness and beautiful descendants — hence the Japanese winter tourism to Yellowknife (Canada) and Tromsø (Norway).
Origin of the word: The expression aurora borealis was coined by Galileo in 1619, combining Aurora (Roman goddess of the dawn) and Boreas (the Greek north wind).