Auroras appear to the naked eye as a very faint, white glow in the night sky to the magnetic north. Many auroras are totally invisible to the naked eye or can only be seen by looking at them indirectly, i.e. out of the corner of your eye. It is extremely rare to see them in colour with the naked eye.
To 'see' the colours of an aurora, you need a digital SLR camera and a tripod. Take a test photograph of the sky to the north, using the settings I suggest below. Then view the image on the telly on the back of the camera and look for green. If you see a strong green arc then there is an aurora present.
Wait until it is dark. Generally the earliest time you can capture the aurora is mid-way between the nautical twilight time and the astronomical twilight time for your location.
You will never see an aurora with the naked eye that looks like the photographs taken on the same night. Cameras, using long exposures, are much more sensitive than the human eye. They capture colours and details that are impossible for the human eye to detect.
There are also major differences in ability to see in the dark from person to person. I have stood side-by-side watching an aurora with someone who could see red & green colours with their eyes, when all I was seeing were shades of white (monochrome). Conversely, I can see extreme sub-visual auroras with my naked eye that are invisible to those with keener night-time, colour vision.
The closest place to where you are staying that has a clear view of the horizon to the north and is without light pollution. Ideally, a view to the north over the sea or a loch is best.
There isn't a specific best time of day to head out looking for auroras, they can happen any time. However, weaker auroras are easiest to capture on camera, and see with the naked eye, in the darkest part of the night. This is around midnight on the winter clocks or around 1:30am on British Summer Time. When there is a moon, the best time is before the moon rises or after it has set.
You cannot see auroras on Skye in June and July because it is too light at night. The best times of year are October through to February.
In a typical year, I usually capture discrete auroras on camera on at least 80 nights, so on average around twice a week here on the Isle of Skye. There are also many more nights when I get the weaker diffuse auroras (what I refer to as 'aurora-tops') on camera.
There are three factors that are essential to getting an aurora: a plasma cloud/solar wind, clear sky and darkness. It is very difficult to achieve all three of these things at the same time, particularly at certain times of year, e.g. in June/July it never gets dark at night. We can generally only tell a maximum of 4 days in advance if there is a likelihood of the Earth passing through a plasma cloud.
In the summer months, the window of darkness is very short, so the chances of meeting all three criteria is much lower. In winter, the period of darkness is much longer, so the chance of getting auroras is much higher.
At all times of year, cloud is the main limiting factor that prevents us from seeing the aurora.
The answer is always "maybe". It depends on clear sky, darkness and a plasma cloud. We can be expecting a major plasma cloud but see nothing because it arrives during daylight or when we have 100% cloud cover. Alternatively, we can be expecting nothing and still get auroras showing spontaneously. There is no way of knowing until true darkness falls on the night in question.
I always post photos on the Glendale Skye Auroras Facebook Page if I am getting the aurora on camera or by eye. You should make sure that the 'sort' option on your facebook feed is set to 'most recent', rather than 'top stories', if you want to be sure of seeing the latest updates. If you have clear sky it is always worth taking test photos at regular intervals to see whether you get any green. You can also subscribe to my text alert service.
There is no point asking anybody else. Go outside and take a test photo, then you will have your answer.
I take test photos of the night sky every 10-15 minutes, 365 days of the year, to check the state of the aurora. By doing this I can tell in advance when an aurora is emerging. This gives me advance warning of if or when a show is likely to occur.
If you are on the O2 or Vodaphone Networks you can get my text alerts as follows:
For other mobile networks, you can receive texts alert via SMS text by following my twitter feed as follows:
You don't have to tweet or use twitter in any way. This is just a free way to be able to send you a text message directly to your mobile.
n.b. If you do not see the 'turn on mobile notifications' option, do the following:
If you don't see any of the options above then you are probably using an iPad, smartphone or tablet. You cannot subscribe on any of these mobile devices. You need to use a proper PC or laptop.
If I am posting photographs of the aurora in Glendale then it can be photographed anywhere in the UK but with a caveat that for every two degrees of latitude further South you will need to increase the exposure on your camera by 1 stop relative to what I am using. My latitude is 57.5°N. If I am photographing the aurora at F4 ISO800 30s then at Bamburgh in NE England (55.6°N) you would need to use exposures of F2.8 ISO800 30s or F4 ISO1600 30s or F4 ISO800 60s. The aurora will also subtend a lower angle in the sky relative to what you see in my photos by 2 degrees for every 1 degrees of latitude further south that you are.
These are the settings I use for my test photos, with some recommendations alongside:
If the aurora is exceptionally bright in your test photo, always reduce the ISO in preference to the shutter speed, as this will reduce camera noise or graininess. Don't even think about reducing the shutter speed until you have reached an ISO level at which your camera produces acceptable amounts of noise. Never close up the aperture, you should always keep to the lowest F-number your lense can support.
If your test photo is very dark, make sure that you have set the exposure to 30s, but then increase the ISO until it becomes nicely exposed.
Always make sure that there is some landscape, building or scenery in your aurora photo to give some scale or perspective. Never just shoot at the sky, unless you are lucky enough to experience a corona (overhead aurora).
Never make any adjustments in your photo-editing software that change the colours from those that your camera originally captured. This results in photos that look 'cartoonish' and totally unnatural.
Practice taking night shots on clear nights when there is no aurora, so that you know what you are doing when the aurora shows. The thing most people have problems with is the focus. Until you can take a nice, sharp, night-time, landscape photo that looks like daylight but with stars, you will not be able to capture an aurora.
A good time to practice is between the end of nautical twilight and astro twilight at your location. This is when the sky often turns purple and there is still some sunlight in the sky but stars will be showing. This allows you to simulate the kinds of exposures needed to capture auroras.
When an aurora is throwing up rays, there is a theory that reducing the exposure to 15s produces better clarity in the photo. However, to maintain the same brightness, this requires the ISO to be doubled. This is fine if you have a high-end, full frame camera but on normal 'crop' cameras the extra noise will be detrimental to the image quality. In my experience here on Skye, varying between 15s or 30s makes little difference to the capture of auroral rays and it is better to leave the exposure at 30s to get as much light into the camera as possible.
When I head out to shoot nightscapes, I take only the camera and lense, pre-fitted to the tripod, spare battery, lense cloth, a small plastic bag and a head torch. I do NOT take lense caps, camera bags, remote timers, gadgets or anything else that I might drop and lose in the dark. The plastic bag is to put over the camera if there is a rain shower. Buy a good quality head torch by Petzl, they are very light, extremely powerful and the batteries last an eternity.
When an aurora is just starting or ending it appears as a fuzzy red/pink band above the horizon on camera, which is known as a 'diffuse' aurora. Once the aurora forms distinct coloured bands of pink and green, shows rays and structure or has a distinct band of clear sky between it and the horizon, it has become 'discrete'.
See my Photographic Guide to the Lifecycle of an Aurora for photographs illustrating how an aurora transitions from diffuse to discrete.
When the Earth is passing through a plasma cloud, the collisions of charged particles in the upper atmosphere cause disturbance to the Earth's geomagnetic field. A magnetometer is a device that measures deviations in the Earth's magnetic field, which might indicate that there is an aurora in progress. The greater the disturbance, the better the aurora is likely to be. The relationship between magnetometer readings and actual auroras in the sky is quite complex. It is possible to have strong auroras in the sky when the magnetometers are at seemingly background levels. Norwegian magnetometers provide the best correlation to visible auroras than UK-based ones. In many cases, UK magnetometers fail to detect activity or react a couple of hours after the light show started. For this reason, I prefer to take regular test photos of the night sky, rather than monitoring magnetometer plots.
See my Photographic Guide to the Lifecycle of an Aurora for a full explanation of the relationship between Magnetometer readings and the lights in the sky.
See my Photographic Guide to the Lifecycle of an Aurora for a full explanation the phases of a Polar Substorm and photographs of how each phase appears on camera.
K is a measure of how much geomagnetic disturbance there is at a particular location on the globe. The higher the K number, the better the aurora. Putting it another way, the higher the K number of the aurora was, the more gutted you will be that you missed it.
Kp is a 3-hour average of K readings from across the planet. Kp values are used for global scientific studies and have no practical use for aurora-hunters wishing to see the lights in the UK. If you feel the need to monitor 'plots' then the Norwegian-Line Magnetometers provide the closest approximation to visible auroras in the UK.
G1, G2 and G3 are alternative names for Kp 5, Kp 6 and Kp 7 respectively.
A Coronal Mass Ejection is a plasma blob that the sun periodically emits from active sun-spots. If the blob hits the earth's atmosphere it can cause some of the best auroras. It is rare to get a direct hit. Think of it like the sun sneezing and the chance of some of the snot hitting an 8000 mile wide rock that is 93 million miles away.
Using the above analogy, if a CME is a sneeze then a Coronal Hole High Speed Stream is runny nose. It is a constant leak of plasma from a hole in the sun's magnetic field that sprays out into space. When one of the coronal holes is facing towards the earth, we can have a gentle dribble of snot hitting our atmosphere and causing auroras that are less intense than those caused by CMEs but continue for days rather than hours.
Bz and Bt are measures of the strength and direction of the interplanetary magnetic field between Earth and Sun. Using a simple analogy, think of the aurora as being like the light from a rechargeable torch. When the Bz is south (negative), the torch is charging. How long the light lasts, and how bright the display, depends on how long it was on charge and how strong the charge was.
See my Photographic Guide to the Lifecycle of an Aurora for an example of how Bz, Bt and Magnetometer readings affect the lights in the sky.
Go to Daily Rise/set and Twilight times for the British Isles and click the map pin that is closest to your location. This link has all the essential times that you need for aurora-watching.
No, it is not bright enough. When you have seen 'video' footage of auroras this is generally done using time-lapse photography, where many hundreds of long-exposure, still images are joined together to create a short piece of video.
No. When the sun is setting, refraction splits the light into the colours of the rainbow: red, orange, yellow, green, blue, indigo, violet. Arcs of each colour appear above the horizon where the sun is going down, the typical colours of a beautiful sunset. There is often a wide, green band around the sunset. Blue, indigo and violet are not strong enough to show until the sun is well below the horizon.
If you get green on camera before the astronomical twilight time for your location, it could just be sunlight, so wait until after astronomical twilight time and then take another photo to confirm that green is still there.
Between nautical and astronomical twilight times, it is not unusual for your test photo to capture a sky that is largely purple or navy blue. This is not an aurora, it is the refraction of the sunlight causing blues, indigos and violets of the colour spectrum to become visible.
No. Orangey glows in the sky, particularly when reflected on clouds or visible in colour as orange by eye, are caused by light pollution from human settlements. The way to tell if a patch of colour is genuine is that you will have stars in it on your test photo.
On a clear night, the moon can actually improve the quality of your aurora photos by illuminating the landscape and, thereby, significantly reducing camera noise. The colours of the aurora take on lovely pastel shades and the images are quite stunning. However, when there is a big moon and very fine misty cloud, the clouds will be lit by the moon and make it difficult to photograph the aurora. This is because increasing the exposure to bring out the aurora colours will also amplify the moonlight on the clouds. When the moon is at 25-50% it gives the optimal illumination to the landscape without washing out the more subtle details and colours of the aurora.
I recommend that you avoid all of them! Any that are based on magnetometer and predicted Kp and Bz values are utterly useless.
The best source of aurora advice is (obviously) my Glendale Skye Auroras Facebook Page. There is also a very good Facebook Group at : AUK - Aurora UK which is useful for real-time reports of aurora sightings from around the UK if you are struggling with cloud cover and wondering whether to persevere with trying to find a gap.