---
title: "Aurora Borealis Explained for Sailors | Boreal Yachting"
url: https://boreal-yachting.com/journal/aurora-borealis
description: "Why the northern lights appear over Tromsø, when the season peaks, and how sailing away from town lights and cloud improves your chances of seeing them."
lang: en
---

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Arctic knowledge: https://boreal-yachting.com/journal/arctic-knowledge

# Aurora borealis: how the northern lights form

By Boreal Yachting crew (https://boreal-yachting.com/about/crew), Skippers and guides, Tromsø

Publication date not available

The aurora borealis is caused by charged particles from the sun striking gases in the upper atmosphere. Green comes from oxygen at around 100 to 300 kilometres. Tromsø sits under the auroral oval at 69.6°N, and the viewing season runs from late September to late March.

Image: Green northern lights above the dark deck and mast of a sailing yacht (https://boreal-yachting.com/generated-images/whalesafari-aurora-1440.webp)

Aurora borealis: how the northern lights form.

Each appearance of the northern lights is different — flickering curtains, rolling smoke, or a sudden corona overhead. The best viewing runs from September to March, when the Arctic night provides a dark sky. Tromsø sits in the middle of the aurora zone, with the lights visible on about two of every three clear nights during the season.

The aurora borealis is caused by charged particles from the sun colliding with gases in Earth's atmosphere. The characteristic green colour comes from oxygen atoms at around 100km altitude; red aurora occurs at higher altitudes, while nitrogen produces purple and blue hues.

Tromsø's location at 69°N places it directly under the auroral oval, the ring-shaped zone around the magnetic North Pole where aurora activity is most frequent.

Viewing the aurora from a yacht, anchored in a dark fjord away from town lighting, gives an unobstructed view stretching from horizon to horizon. Calm water reflects the display, and there is little ambient noise.

Photography tips: use a tripod, set ISO to 1600–3200, aperture to the widest available (f/2.8 or wider), and exposure time to 5–15 seconds. Manual focus set to infinity is essential. Modern smartphones with night mode can also capture good aurora images.

The best aurora forecasts combine solar wind data with local weather forecasts. Our crew monitors both and will wake guests if a strong display occurs during the night. Some of the strongest auroras happen after midnight, when the magnetic field is best aligned.

Related experience: Northern Lights Sailing (https://boreal-yachting.com/experiences/northern-lights-sailing).

Where this sails: Sailing Tromsø (https://boreal-yachting.com/destinations/tromso).

About the author

## Boreal Yachting crew

Skippers and guides, Tromsø

Written by the Boreal Yachting editorial team using operational knowledge from the skippers and guides who sail Northern Norway and Svalbard.

Meet the crew: https://boreal-yachting.com/about/crew

## Read next

### The Arctic climate: what to expect

The coast of Northern Norway is warmed by the Norwegian Atlantic Current, so the sea stays ice-free all year despite lying above the Arctic Circle. Summer air is usually 8 to 15°C and winter around freezing at the coast, with weather that changes within hours.
https://boreal-yachting.com/journal/arctic-climate

### Need to know when sailing in Northern Norway

Sailing Northern Norway needs attention to three things: tidal streams that reach seven knots in narrows such as Rystraumen, fall winds that arrive without warning off steep terrain, and distances between harbours. Forecasts from yr.no and marine VHF are reliable and should be checked daily.
https://boreal-yachting.com/journal/need-to-know-sailing-northern-norway

All writing in the Journal: https://boreal-yachting.com/journal

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