
© Markus VarikPink or white auroras appear when energetic particles from space descend lower than usual
WHITE AURORAS? Auroras are usually green. Occasionally, other colors appear: red, purple, blue. One color that never shows itself, however, is
white -- that is, not until last night. "I saw white auroras over Tromsø, Norway!" reports veteran observer Markus Varik. He recorded the phenomenon in this photo:
"I've been working more than 400 nights as a Northern Lights guide, and although sometimes I think I've seen it all,
never have i witnessed white auroras like that," says Varik. "It was amazing to see it unravel white like that in front of my eyes. Pure magic!"
Auroras get their colors from specific elements in Earth's upper atmosphere. Green auroras, for instance, come from atomic oxygen; blue is associated with molecular nitrogen. No element produces white. So where did it come from?
An important clue: Elsewhere in Scandinavia, intense ribbons of pale pink appeared. Here is a specimen recorded by an automated
auroracam in Abisko, Sweden:

© AuroracamThese pink and white aurora seen in Sweden are somewhat rarer
Sarah Skinner, a tour guide with Lights over Lapland, saw the display: "OMG, it was the pinkest aurora ever!"
The 'white auroras' Varik photographed might actually be pink auroras filtered and paled by low-hanging clouds. Indeed, there is a strong hint of pink in Varik's photo.
Pink auroras are somewhat rare, but hardly unprecedented.
They appear when energetic particles from space descend lower than usual, striking nitrogen molecules at the 100 km level and below.
Comment: From Spaceweather.com:
This is a "coronal hole"--a region in the sun's atmosphere where the magnetic field opens up and allows solar wind to escape.
We've actually seen this coronal hole before -- at least twice. For the third month in a row, a large hole in the sun's atmosphere is turning toward Earth. It is rotating around with the sun, strobing Earth like a lighthouse every ~27 days.
The last two times we experienced its solar wind (Oct. 25-28 and Nov. 23-26), G1- and G2-class magnetic storms sparked bright polar auroras.
For the third day in a row, Earth is inside a stream of solar wind blowing out of a large hole in the sun's atmosphere. This is causing magnetic unrest and bright auroras around the poles. NOAA forecasters estimate a 35% chance of
G1-class geomagnetic storms on Dec. 24th.
Also see:
Comment: From Spaceweather.com:
This is a "coronal hole"--a region in the sun's atmosphere where the magnetic field opens up and allows solar wind to escape. We've actually seen this coronal hole before -- at least twice. For the third month in a row, a large hole in the sun's atmosphere is turning toward Earth. It is rotating around with the sun, strobing Earth like a lighthouse every ~27 days. The last two times we experienced its solar wind (Oct. 25-28 and Nov. 23-26), G1- and G2-class magnetic storms sparked bright polar auroras.
For the third day in a row, Earth is inside a stream of solar wind blowing out of a large hole in the sun's atmosphere. This is causing magnetic unrest and bright auroras around the poles. NOAA forecasters estimate a 35% chance of G1-class geomagnetic storms on Dec. 24th.