Aurora Borealis in the clouds from HCH office back patio; 11 May 2024
Aurora Borealis visible from Colorado Springs (sort of…)
Aurora Fun Facts
An aurora (pl. aurorae or auroras), also commonly known as the northern lights (aurora borealis) or southern lights (aurora australis), is a natural light display in Earth’s sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of brilliant lights that appear as curtains, rays, spirals, or dynamic flickers covering the entire sky.
Auroras are the result of disturbances in the Earth’s magnetosphere caused by the solar wind. Major disturbances result from enhancements in the speed of the solar wind from coronal holes and coronal mass ejections. These disturbances alter the trajectories of charged particles in the magnetospheric plasma. These particles, mainly electrons and protons, precipitate into the upper atmosphere (thermosphere/exosphere). The resulting ionization and excitation of atmospheric constituents emit light of varying color and complexity. The form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceleration imparted to the precipitating particles.
Most of the planets in the Solar System, some natural satellites, brown dwarfs, and even comets also host auroras.
Etymology (the origin of a word and the historical development of its meaning)
The term aurora borealis was coined by Galileo in 1619, from the Roman Aurora, goddess of the dawn and the Greek name for the north wind (Boreas).
The word aurora is derived from the name of the Roman goddess of the dawn, Aurora, who travelled from east to west announcing the coming of the sun. Ancient Greek poets used the corresponding name Eos metaphorically to refer to dawn, often mentioning its play of colors across the otherwise dark sky (e.g., “rosy-fingered dawn”).
The words borealis and australis are derived from the names of the ancient gods of the north wind (Boreas) and the south wind (Auster) in Greco-Roman mythology.
Occurrence
Most auroras occur in a band known as the “auroral zone”, which is typically 3° to 6° (approximately 330–660 km) wide in latitude and between 10° and 20° from the geomagnetic poles at all local times (or longitudes), most clearly seen at night against a dark sky. A region that currently displays an aurora is called the “auroral oval”, a band displaced by the solar wind towards the night side of Earth. Early evidence for a geomagnetic connection comes from the statistics of auroral observations.
In northern latitudes, the effect is known as the aurora borealis or the northern lights. The southern counterpart, the aurora australis or the southern lights, has features almost identical to the aurora borealis and changes simultaneously with changes in the northern auroral zone. The aurora australis is visible from high southern latitudes in Antarctica, Chile, Argentina, South Africa, New Zealand and Australia. The aurora borealis is visible from areas around the Arctic such as Alaska, the Canadian Territories, Iceland, Greenland, Norway, Sweden, Finland, Scotland, and Siberia. On rare occasions the aurora borealis can be seen as far south as the Mediterranean and the southern states of the US. During the Carrington Event, the greatest geomagnetic storm ever observed, auroras were seen even in the tropics.
A geomagnetic storm causes the auroral ovals (north and south) to expand, bringing the aurora to lower latitudes. The instantaneous distribution of auroras (“auroral oval”) is slightly different, being centered about 3–5° nightward of the magnetic pole, so that auroral arcs reach furthest toward the equator when the magnetic pole in question is in between the observer and the Sun. The aurora can be seen best at this time, which is called magnetic midnight.
Auroras seen within the auroral oval may be directly overhead. From farther away, they illuminate the poleward horizon as a greenish glow, or sometimes a faint red, as if the Sun were rising from an unusual direction. Auroras also occur poleward of the auroral zone as either diffuse patches or arcs, which can be subvisual.
{ From: https://en.wikipedia.org/wiki/Aurora }
Equipment
Sigma 14mm 1:1.8DG lens on Canon EOS 5DSR, on stationary tripod, controlled with Pixel TW-283 wireless shutter release remote control
Capture & processing notes
Motivated by Ann Chavtur’s FB post image and video of her capture of the Aurora Borealis on Friday night, 10 May 2024 from her home in Monument, I decided to give imaging it a try. Her video had clouds moving in, that didn’t obscure the Aurora, so I decided even though there were some clouds, I would give imaging it a try. Her post said “point your camera north” and take wide angle images. I started out on the front patio, but moved to the patio outside our home office instead – to have a better foreground than the corners of the house. Ann’s images were 14mm, f/2.8, ISO 1600, 8 seconds. When I used those settings, it seemed to be too bright (likely due to the light pollution in town vs Monument), so I backed off to 14mm, f/2.8, ISO 1600, 4 seconds. It took me a few minutes of adjusting the exposure settings, fiddling with the framing, and deciding if this whole thing was worth doing – until I finally told myself to… “just do it, it’s only bits on the memory card that can be erased in the morning…” I captured 820 images between 11May, 2307MDT and 12 May, 0057MDT.
I used 775 of the images to create a time-lapse video to show the cloud movement and color changes. The Aurora wasn’t visible – even though the clouds looked like they had dissipated at times to my eye, to the 4 second exposure the camera thought otherwise. But the video shows a very interesting changing of the cloud color throughout the ~1:25 hour period.
Sequence: Set-up framing/exposure images: 45x 2-8 second images; 11May2024, 2307MDT – 2339MDT. For video’s final framing and exposure settings, captured 775×4 sec, 14mm, f/2.8, ISO 1600, 4 seconds; captured 11May2024, 2340MDT – 12May2024, 0057MDT from HCH office patio.
Capture: 11May2024, 2340MDT – 12May2024, 0057MDT
Shooting location: HCH back patio, Colorado Springs, Colorado
Processing: Video: Initial color consistency editing in LR, import and create video in PS. Individual image: Edit in LR/PS.