Aurora colours explained: why green, red and pink?

The most common aurora colour is a yellowish green, produced by oxygen atoms around 100–120 kilometres up. Red also comes from oxygen, but much higher, while the purple or pink fringe along the bottom comes from nitrogen. If the aurora looks greyish white to your eyes but green and pink on your phone screen, that is down to how human eyes work in the dark, not to the camera "lying".

Why the aurora has colours at all

The aurora appears when electrons from the magnetosphere collide with gases in the upper atmosphere (see what the aurora is). The atom or molecule that is hit gains extra energy and gets rid of it by emitting light. Each gas emits at very specific wavelengths, so the auroral spectrum is made of sharp lines and bands rather than a smooth rainbow. The first systematic studies of this spectrum were made by the Norwegian physicist Lars Vegard.

Two things decide the colour: which gas is hit, and at what height. The height in turn depends on how much energy the electrons carry. The more energy, the deeper they penetrate the atmosphere.

Green: oxygen at 557.7 nanometres

The strongest line in the aurora comes from atomic oxygen at 557.7 nm and gives the familiar yellow-green colour. The oxygen atom holds on to its energy for less than a second before emitting light; one source gives 0.7 seconds, NOAA about one second. That sounds short, but in dense air the atom has time to bump into other molecules and lose the energy before it can glow. That is why there is almost no green aurora below about 95 km. A large study using all-sky cameras in northern Finland and Sweden found that the green emission is typically brightest at around 114 km.

Red: oxygen high up, and during big storms

The red light also comes from oxygen, with its main line at 630.0 nm. This time the atom has to hold on to its energy for more than a hundred seconds before it emits. It can only manage that in very thin air, so red aurora sits high, roughly 200–300 km or more. Because the atoms drift with the wind before they glow, red aurora often looks diffuse, without sharp structure.

Red is often caused by low-energy particles. It is typical of the daytime aurora over Svalbard, and it often dominates when powerful storms push the aurora far south. Because the red glow is so high, it can be seen above the horizon from places a long way off. Many Norwegians remember the night of 10–11 October 2024, when the broadcaster NRK received photos of intense red aurora from places such as Sortland in Vesterålen, Asker near Oslo and Mandal on the south coast. On the night of 11–12 November 2025, intense red aurora was also reported from the far north of Finnmark. Read more about such events in our articles on geomagnetic storms and the aurora in southern Norway.

Purple, pink and blue: nitrogen

When electrons carry extra energy they dive deeper, where nitrogen dominates and only emissions with a very short lifetime get out. The nitrogen molecule glows almost instantly in deep blue and red. Together they look purple or pink and create the coloured lower edge on a green curtain. Store norske leksikon notes that the blue-violet colour mainly comes from ionised nitrogen, and its blue line at 427.8 nm sits at about the same height as the green.

During the May 2024 storm, pink and purple dominated the photos from southern Norway, according to NRK. A pink lower fringe is therefore a sign that the aurora is energetic and active, often during the breakup phase.

A rarer phenomenon is the so-called sunlit aurora. Around sunrise and sunset, the tops of auroral rays can be lit by sunlight high in the atmosphere, and according to NOAA they can then take on a purplish tint.

Why your eyes see grey and the camera sees green

Your eyes have two kinds of light sensors. About 95 percent are rods, between 100 and 125 million of them. They are extremely sensitive to light but cannot tell colours apart. Colour vision comes from the cones, which need more light. In the dark it is the rods that do the work, so a faint aurora looks grey, white or like a pale cloud. NOAA points out that the many reports of "white aurora" really come down to this: the eye picks out brightness before it can distinguish colour. Only when the aurora gets fairly bright will you see clear green, and in the strongest outbursts pink and red as well.

A camera does not have this problem. It collects light over several seconds at a time, and its sensor records colour even in dim light. NOAA notes that modern digital cameras are often more sensitive than the human eye and can capture the aurora and its colours when it is too faint for us to see. That is why the phone picture often looks far more dramatic than what you actually experienced.

A few practical tips:

• Give your eyes at least a few minutes in the dark, and avoid looking at a bright screen. Your night vision needs time to settle.
• If you are unsure, take a test shot facing north. A green arc in the photo means the aurora is there, even if you only see a grey streak.
• Do not expect to see red with the naked eye on an ordinary evening. It usually takes strong activity.

To capture the colours yourself, our guides to photographing the aurora with a phone and with a camera give concrete settings.

The colours and what they tell you

In short

• Green is oxygen at around 100–120 km, red is oxygen higher up, purple and pink are nitrogen lower down.
• Your eyes see a faint aurora as grey because the rods, which take over in the dark, cannot see colour.
• A camera collects light over time and so shows colours you cannot see directly.
• A pink lower edge means strong activity, so that is the moment to look up. Check tonight's verdict for your location.