Each type of aurora represents a unique interaction between solar winds and Earth’s magnetic field. Let's explore the main types of auroras below.
1. Auroral Curtains
Auroral Curtains, Tromso | Image credit: StockSnap, Pixabay.
Auroral curtains are perhaps the most well-known form, especially in the Arctic. These curtains resemble long, flowing sheets of light that ripple and swirl across the sky.
Typically green, but can also appear in shades of red or purple, depending on atmospheric conditions. Curtains are dynamic and can quickly morph into other aurora types.
2. Auroral Arcs
Auroral Arcs, Lapland, Finland | Canon EOS 7d Mark II, f1.3, exposure 15s | Image credit: Moona Tarvainen, Pixabay.
Auroral arcs are slightly than other types of auroras. Scretching across the northern horizon in a smooth, glowing band of light.
While these arcs may appear still, a sudden brightening often signals an impending geomagnetic substorm. You get the idea, transforming them into a vibrant display (see spaceweatherlive.com)
3. Auroral Pillars
Auroral Pillars, Abisko, Finland | Sony Slt-A55v | Image: MartinStr, Pixabay.
Auroral pillars are tall beams of light that rise up from the horizon and extend into the sky. These are more commonly seen in mid-latitude regions, though they can also be visible from farther away due to their great height, often stretching hundreds of miles.
Pillars tend to be green at the base with hues of red or purple at the top, offering a striking contrast of colors as they dance across the horizon.
4. Auroral Rays
Rays are similar to pillars but are more frequently seen in Arctic regions. Since rays can appear directly above you, they offer a different perspective compared to horizon-bound auroral pillars.
Similar to pillars, auroral rays can shift and morph rapidly, sometimes transforming into other aurora forms, making them particularly exciting to watch. Pretty amazing!
5. Auroral Corona
Auroral Corona, Norway | Canon EOS-1d X | Image: John Huang, Pixabay.
One of the most breathtaking and dramatic forms of aurora is the corona. The corona occurs directly overhead, with rays, pillars, and streaks of light shooting up from all directions, converging in the sky’s zenith. This, something that will be seen in the following video.
6. STEVE (Strong Thermal Emission Velocity Enhancement)
Auroral STEVE, Norway | Canon EOS 5d Mark III | Image: Noel Bauza, Pixabay.
STEVE is a relatively new discovery, first classified in 2016. Though it’s not technically an aurora, STEVE is often spotted alongside auroras, taking the shape of a narrow arc of light that stretches east to west for hundreds or even thousands of kilometers. STEVE emits a faint purplish glow and is typically accompanied by a green “picket fence” formation below it. STEVE sightings are more common in mid-latitudes, adding to its rarity.
7. Deep Sky or Photographic Auroras
Auroral Deep Sky, Norway | Image: r3dmax, Freepik.
Deep sky auroras are invisible to the naked eye and can only be captured through the lens of a camera using long exposures. These auroras occur during weaker geomagnetic activity when human vision fails to detect the light, but sensitive camera sensors can pick up the faint glow. It’s a reminder that there’s often more happening in the sky than we can see with our own eyes.
8. Stable Auroral Red (SAR) Arc
The Stable Auroral Red Arc, or SAR arc, is an incredibly rare type of aurora that appears as a faint red band in the sky. These arcs are closely associated with geomagnetic storms and STEVE but are much harder to spot. One of the most notable recent SAR arcs occurred on November 5, 2023, when a strong geomagnetic storm allowed it to be photographed as far south as Texas.
9. Pulsing Auroras
Pulsing Auroras, Norway | Image: r3dmax, Freepik.
Pulsing auroras appear in patches rather than continuous streaks of light. They often emerge after the main auroral activity of a substorm has subsided, creating patches of light that pulse on and off across the sky. These auroras can be difficult to appreciate in real-time but are more easily noticed in time-lapse photography.
10. Blue Auroras
Auroral Blue, Norway | Nikon D810, f1.4, exposure 8s | Image credit: Jason Gillman, Pixabay.
Blue auroras are a rarer variety, appearing when auroral activity reaches particularly high altitudes, where sunlight can still illuminate the upper atmosphere. These auroras are most often seen shortly after sunset or before sunrise, when the light of the sun reaches just the right angle to produce the striking blue hue.
11. Nitrogen Fringe
Auroral Nitrogen Fringe, Norway | Canon EOS Rebel T3, f4, exposure 4s | Image credit: makyvontravel, Pixabay.
A nitrogen fringe refers to the bright red or pink edge that can sometimes appear at the base of an active auroral display. This effect is caused by nitrogen atoms in the atmosphere becoming excited by the geomagnetic storm. Nitrogen fringes are commonly seen in the Arctic during highly active displays and add an extra layer of vibrancy to the spectacle.
12. Diffuse Auroras
Diffuse Auroras, Finland | Nikon D750, f2.2, exposure 15s | Image credit: Joonas Kaariainen, Pixabay.
Diffuse auroras appear as soft, cloud-like glows rather than sharp, structured forms. Unlike the more dynamic curtains or arcs, diffuse auroras lack well-defined shapes and are generally dimmer. They are often seen during weaker geomagnetic activity and can be hard to detect without a camera due to their faint nature. Diffuse auroras are common but tend to be overlooked in favor of brighter displays.
13. Patchy Auroras
Patchy Auroras, Norway | Canon EOS 400d Digital, f5.6, exposure 30s | Image credit: Ken Ole Vian, Pixabay.
Patchy auroras are similar to diffuse auroras, but they are broken into distinct "patches" or blobs of light. These patches float independently across the sky and sometimes pulse in brightness. Patchy auroras are most often observed during moderate geomagnetic activity, frequently at lower latitudes. They can appear alongside other auroral forms, adding complexity to a display.
14. Auroral Bands
Auroral Bands, Alaska | Sony Ilce-7m3, f4, exposure 25s | Image credit: Baumhan, Pixabay.
Auroral bands are narrow, ribbon-like strips of aurora that stretch across the sky. These bands are typically more stationary than curtains or rays and are observed during periods of lower geomagnetic activity. Though subtle, auroral bands can still be quite captivating, especially when they glow in vibrant greens or reds and add elegance to the night sky.
15. Green Arc Auroras
Green Arc Auroras, Norway | Nikon D50 | Image credit: Cheerfully_lost, Pixabay.
Green arc auroras are a subtype of auroral arcs characterized by their bright green color, caused by oxygen atoms emitting light at high altitudes. These arcs stretch across the sky, offering a vivid, smooth band of green. Green arcs are especially common at high latitudes and are a classic feature of auroral displays during quiet nights before stronger geomagnetic storms occur.
16. Red Auroras
Red auroras are a rare phenomenon that occurs at much higher altitudes (300 to 500 kilometers) than the more common green auroras. The red color is caused by oxygen atoms emitting light at a lower energy level, producing a striking red glow. Red auroras usually only appear during strong geomagnetic storms and are most often seen near the poles, although they have been observed at lower latitudes during particularly intense storms.
17. Proton Auroras
Proton Auroras, Norway | Nikon D810, f2, exposure 8s | Image credit: Jason Gillman, Pixabay.
Proton auroras are caused by high-energy protons from the solar wind colliding with Earth's atmosphere. Unlike electron-driven auroras, proton auroras tend to be fainter and more diffuse. They appear as a steady, dim glow rather than bright, dynamic patterns. Proton auroras typically occur during stronger solar storms and are often observed in conjunction with other types of auroras.
18. Diffuse Pulsating Aurora
Diffuse Pulsating Aurora, Norway | Canon EOS 6d, f2.8, exposure 25s | Image credit: Pexels, Pixabay.
Diffuse pulsating auroras are a subtype of pulsing auroras that cover a larger area and have a cloud-like appearance. These patches of auroral light pulse in and out, typically at intervals of a few seconds. Unlike sharply defined pulsating auroras, diffuse pulsating auroras have a more nebulous, blurred look. They are more easily observed in time-lapse photography but can be spotted during lower levels of auroral activity.
19. Omega Auroras
Omega Auroras, Finland | Canon EOS 700d, f3.5, exposure 8s | Image credit: Brigachtal, Pixabay.
Omega auroras are named for their resemblance to the Greek letter omega (Ω). These rare formations take on an inverted "U" shape and are typically seen during substorms. As the aurora evolves, omega-shaped arcs can morph into more complex structures, but the distinctive looped form makes them stand out. Omega auroras add a unique twist to the typical auroral arcs.
20. Pickering’s Triangles
Pickering’s triangles are an unusual and extremely rare form of aurora, first observed in 1899. They appear as small, triangular patches of light within a larger auroral display, often alongside curtains or arcs. The exact cause of these triangles remains unclear, but they are thought to result from complex interactions between the solar wind and Earth's magnetic field. They are seldom seen but add a curious element when they do appear.
21. Dunes Auroras
Dunes auroras are a recently discovered phenomenon, first documented in 2020. They manifest as parallel, wave-like patterns in the sky, resembling sand dunes. These green waves are thought to be caused by mesospheric bores, which are ripples in the upper atmosphere. Dunes auroras are rare and fascinating, adding a new dimension to the variety of auroral shapes observed so far.
22. Inverted V Auroras
Inverted V auroras take the shape of a broad “V” or chevron and are most commonly seen during quieter auroral displays. The sharp, angular formation of the inverted V gives them a distinct appearance, contrasting with the flowing shapes of curtains or arcs. These auroras typically occur at lower geomagnetic activity levels, providing a unique, but subtle, form to look out for during quieter nights. See the file.
Now, get ready for... Auroras in motion!
The footage below nicely highlights the diverse types of auroras in action, capturing their stunning colors and movements.
Prepare to be mesmerized (really!) as you watch these natural wonders unfold!
Northern Lights in real time | Source: Jonna JintonToo far from the poles? Experience the northern lights from your couch by watching live aurora webcams, broadcasting real-time views from various locations.
Stay cozy with our comfy Northern Lights Hoodie #10 while following the aurora forecast at SpaceWeatherLive.com.
Until next time!