Colours of the Northern Lights

The Northern Lights are most often green, but they can also appear red, pink, purple, blue and sometimes yellow or white.

The colour depends mainly on two things: which gas is producing the light and how high in the atmosphere the interaction occurs. Oxygen produces the familiar green aurora as well as high-altitude red, while nitrogen contributes blue and pink tones.

Several colours can appear during the same display, particularly when aurora activity is strong.

Why Do the Northern Lights Have Different Colours?

The Aurora Borealis is a phenomenon caused by solar winds, which blow electrons or electrically charged particles into atoms and molecules in Earth's upper atmosphere. There, they collide with oxygen and nitrogen. These atoms and molecules absorb energy and then release it as light.

The colour we see depends on the gas involved, its altitude and the energy of the incoming particles.

The best time to see northern lights is from September to April. We recommend checking out an Aurora Forecast to predict visibility.

The Spectrum of Northern Lights Colours

The primary colours of the Northern Lights are green, red, and purple, though other colours like pink, blue, and yellow can also occasionally appear.

Green

Green is the most common Northern Lights colour. It is produced when energetic particles excite oxygen in the upper atmosphere, typically around 100–200 kilometres above Earth.

The excited oxygen releases energy at a wavelength of about 557.7 nanometres, which our eyes perceive as green. This emission is responsible for many of the bright green arcs and curtains associated with the aurora.

Purple

Purple hues in the northern lights are less common but visible every now and then, especially during intense solar storms. These colours are usually produced by a mix of nitrogen and oxygen molecules at varying altitudes and with different energy levels. The specific shades of purple and pink depend on the altitude and the types of molecules involved.

Pink

Pink often appears at the lower edges of the red and green areas or as a mix of red, green, and blue.

Yellow

Yellow auroras are relatively uncommon as well. They result from a combination of oxygen and nitrogen molecules being excited at different altitudes, producing yellowish hues.

Red

Red is often seen in conjunction with green auroras. It occurs at higher altitudes, typically between 150 and 200 miles (240 to 320 kilometres) above the Earth's surface. Red auroras are the result of charged particles interacting with high-altitude oxygen atoms. The oxygen at this altitude emits red or crimson light when excited.

Blue

Blue auroras are rarer than green or red. They occur at lower altitudes, usually below 60 miles (100 kilometres). Blue is produced when electrons collide with nitrogen molecules in the upper atmosphere, causing them to emit blue light.

Factors Influencing the Colours of the Aurora Borealis

The exact colours and their intensity can vary depending on the energy and speed of the incoming charged particles, the altitude at which the collisions occur, and the types of gases involved in the interactions.

• Altitude: The altitude at which the solar particles collide with the Earth's atmosphere plays a significant role in determining the colours of the auroras. Different gases at varying altitudes react differently when excited, leading to a spectrum of colours.
• Type of Gas: The Earth's atmosphere is primarily composed of oxygen and nitrogen. When these gases are excited by charged solar particles, they emit light in specific colours. Oxygen, for instance, can produce green or red light, while nitrogen can produce blue or purple light.
• Level of Solar Activity: The intensity of solar activity can influence the colours and brightness of the auroras. Higher levels of solar activity can lead to more vibrant displays and a broader range of colours.

Photographing the Northern Lights

Cameras are more sensitive to colour in low light than the human eye, which is why aurora photographs often show stronger greens, reds and purples than you remember seeing in person.

Longer exposures can collect more light, but excessively long exposures may blur the movement of the aurora. For camera settings and practical advice, see our guide to photographing the Northern Lights in Iceland.

Why Do Northern Lights Colours Look Stronger in Photos?

Northern Lights often appear brighter and more colourful in photographs than they do to the naked eye.

In low light, human colour vision becomes less sensitive, so a faint aurora may look pale green, grey or almost white. A camera can collect light for longer and record colour more effectively, revealing greens, reds and purples that were difficult to distinguish in person.

When the aurora becomes bright and active, its colours can also be clearly visible without a camera.

Best Places and Times to Witness the Spectrum of Aurora Borealis Colours

Northern Lights can be seen in high-latitude regions including Iceland, northern Scandinavia, Alaska and northern Canada. In Iceland, the main viewing season runs from late August into early April, when skies become dark enough to see the aurora. Here are the best places to see the northern lights in Iceland.

Where Can I Learn About Northern Lights in Reykjavík?

Perlan's Áróra Northern Lights Show explains the science and stories behind the aurora using an 8K planetarium projection system and surround sound.

The show lets visitors see how Northern Lights can change in colour, shape and intensity, including during months when Iceland's summer skies are too bright to see the aurora outdoors.