How I Photographed the Aurora Borealis on April 7, 2000

It is close to midnight, April 6, 2000. I am on my way home from a four hour lecture about our mountaineering expedition to Huascaran in Peru which I gave at the TerĪ¦ club in the local university students' hall of residence in Brno. It is a clear night and I take a shortcut through the woods and then down a field path with a rucksack containing a slide-projector and several boxes of slides. I have been taking this road to and from work for over 16 years, often at night. So I think I know where to expect the lights of the city of Brno and how they should appear. Suddenly, I am attracted by a faint glow (much weaker than the lights from the city centre) coming from a place where nothing should be at all. Moreover, it seems to be a green light in color. I am not completely sure about the color as the eye does not perceive faint light in color. Knowing that the Sun is approaching the maximum of its eleven-year cycle I am struck by the idea that it could be aurora borealis. I begin to carefully observe the sky while continuing to walk. I notice a very weak glow at one spot on the sky over the lights of Brno which seems to be red. No street lighting has such a color. I start to hurry so as to be home as soon as possible. At home, still rather puzzled, I grab the tripod, mount a Praktica camera on it, screw on a 2.8/29mm wide-angle lens, fetch a box with Fujicolor Superia 800 from the fridge, add a 2.8/20mm super wide-angle Flektogon lens to the contents of the rucksack and rush back to the field, away from the vile street lighting. When I reach the field I soon find out that something of minor importance is missing - the film I had taken out of the fridge. A quick run home and back ensues, this time with the camera loaded. When I escape from the strong city lights I calm down and start to study the sky. I see a faint glow of some kind but still I am not sure whether it might be the aurora borealis. Exactly at 1:00 local time (summer CET) I take the first picture using a 2 minute exposure because I have a hunch that what I see may be real and that it might be polar lights. After about 10 minutes I am absolutely positive but the intensity of the lights is not such as to allow me to make good pictures. At about 1:15 something unexpected happens. All northern sky is filled with beautiful shining strips. The horizon is green and above it glows a bloodred belt in which rays of light appear and again vanish within minutes or just tens of seconds. This is a natural spectacle of astonishing beauty. Suddenly I notice a strip running almost to the zenith with a "liquid" or rather glittering shine to it. Mesmerized, I take pictures. After about 30 minutes the lights grow weaker and having on only light clothes I begin to feel frozen to the bone. I quickly run home and wake up my wife Zuzana and daughter Hana. The younger daughter Zdena insists she wants to sleep. Later I discover she was talking in her sleep and remembered nothing. She was really sorry that I did not wake her up and I have permission to use more "brutal" methods next time. Our threesome sets off to the field, I am wearing an anorak. Now I have plenty of time to watch the lights and together we relish the view of this fascinating natural phenomenon which took me 46 years to behold. At three a.m. the glow fades away and we head home. The following days find me increasingly restless. In the evening I, in turn, scan the pictures and then look up to the north sky to see whether the magnificent spectacle will be repeated. The product of my excitement and restlessness is this account.

What I did not know on the night of April 6 to April 7.

On April 4, 2000 just before 16.00 hours UT the coronograph of the SOHO spacecraft records a giant coronal mass ejection (left-hand picture). Two days later a massive shock approaches the Earth. There, it is recorded, shortly after 16.00 hours, by the ACE space probe measuring solar wind speed. The speed of the solar wind abruptly increases from below 400 km/s to over 600 km/s (right-hand picture). After the shock wave's arrival there is massive disturbance to the magnetic field of the Earth. As a result, magnetic storms arise and soon after dark auroras are visible in Central Europe. Their magnitude exceeds all the polar lights observed over dozens of years.

The photographs and diagram by NASA/ESA Solar and Heliospheric Observatory (SOHO/LASCO)and NASA ACE.