Northern Lights: Why did the Aurora Borealis look better through a camera than to the naked eye?
Thousands of people were lucky enough to see one of the best and rarest sightings of the Aurora Borealis, also known as the Northern Lights, on Friday night just by stepping outside and looking up.
It was confirmed on Saturday that Earth had been hit by a rare "G5 Extreme Solar Storm" by NOAA's Space Weather Prediction Center - something which last happened in October 2003.
Images flooded social media from across the UK, even as far south as Cornwall, Kent and the Channel Islands, which rarely see this natural phenomenon.
However, it quickly became apparent that the aurora looked even better in images and videos than the actual colours in real life seen with the naked eye.
Why does the Aurora Borealis look better through a camera than to the naked eye?
The short answer is it's to do with wavelengths, and how sensitive our eyes are. Let me explain.
The aurora is the interaction of the solar wind with the Earth's atmosphere. This interaction is drawn towards the poles due to the earths magnetic field.
Charged particles from the sun, primarily electrons and protons, collide with gases in the Earth's atmosphere, typically oxygen and nitrogen.
These collisions emit light at various wavelengths, creating vibrant displays of colour in the sky, often appearing as curtains, arcs, or bands of light.
The colours are determined by the type of gas particles involved and the altitude at which the collisions occur.
The human eye is not as sensitive to these wavelengths as our cameras are.
Using a long exposure on your camera allows more light into the lens, providing you with the colours that you see in photographs and videos.
Below is what the Aurora looks like with the naked eye
Below is the same image with a camera
Remember that our eyes are not adapted to seeing very much in the dark so being able to pick up on these colours is difficult.
The brightest auroras are similar to moonlight which is on the edge of the useful light for most humans.
This is why some people may not have seen the pinks and reds in particular - if at all - with the naked eye, but they show up much more clearly through a camera.
Others may have not seen such vivid colours for any of the following reasons:
Too much light pollution, meaning their eyes just didn’t adjust or their cameras were over-exposed to the light;
Weather conditions: Cloud cover, mist or fog prevented the celestial dome being visible;
The device used: The exposure settings on the camera were not correct;
Solar storm intensity: they looked when the aurora levels were not strong enough for their latitude and location.
What causes the different colours of the aurora?
As mentioned above, it's the charged particles from the sun which collide with gases in the atmosphere.
The altitude and type of gases involved determines the colour.
Greens appear due to interactions with oxygen, red is from oxygen in the upper atmosphere while blues and purples are due to the interaction of nitrogen.
Why was this aurora so rare for the south of the UK?
The reason this is a once-in-a-lifetime event is that firstly the frequency it occurs is low. The last time they were this strong was back in 2003.
But even if the aurora occurs, the weather - for example - may not allow you to see it. Or the moon may be too bright. There are a number of factors involved that make this an unusual occurrence.
It’s very, very rare for anywhere in the UK to see the aurora directly overhead and so vividly.
This is because its depended upon the strength of the solar storm.
The more intense the storm, the further south the aurora can be visible.
All these things make it a once-in-a-lifetime opportunity to see this natural wonder from just outside where you live.
What is the rarest colour to see in the Aurora Borealis?
The rarest colours to see are deep blues or purple, which are a result of ionised nitrogen at the lowest altitudes in the thermosphere.
Only strong solar storms have the power to punch this low in altitude, providing a delightful spectacle for fortunate onlookers who catch a glimpse of it.
How high is thermosphere where the aurora occurs?
Found in the upper atmosphere, lies the thermosphere between 53-375 miles (85-600km) from Earth.
The lower level of the thermosphere is where you can find the aurora, typically occurring between 80-250 miles (120 to 400 km) above the Earth's surface.