And pretty much everywhere else
First, a pretty picture:
The sun is nearing the peak of its eleven year sunspot cycle. That means lots of sunspots and associated activity. Solar prominences, visible to the naked eye during the eclipse, are bands of plasma entrained in the magnetic field connecting pairs of sunspots. Once in a while, these break out in solar flares. Lately, the sun has produced a series of X-class flares (the largest type) with associated coronal mass ejections (CMEs) that send huge blobs of plasma hurtling out into space.
Space is big, so CMEs usually don’t impact Earth. But sometimes they do, and they have a number of effects. The plasma impinges on Earth’s magnetic field, which funnels charged particles towards the poles. When these high-speed particles hit atoms and molecules high up in the atmosphere, they transfer energy that excites quantum states. The relaxation of these states leads to the emission of the light we perceive as aurora.
I heard there was a possibility of aurora being visible at our latitude Friday night. I didn’t expect much – the northern lights are notoriously fickle, and usually only appear much further to the north – hence the name. It has to be fully dark to see them at all, so I walked out at about 10 PM and looked up. Not much. Maybe some thin clouds. Only that’s a strangely shaped cloud. And, as my eyes adjusted, one shone red, the other green. The northern lights had come to me.
NOAA has a good explainer. The greens and reds are from excited atomic oxygen, at different altitudes owing to the different lifetimes of the associated quantum states. Atoms can be de-excited as well as excited by collisions, so we only get emission lines when the density* of surrounding atoms is low enough that light gets emitted before collisional de-excitation. That means the green comes from oxygen over 100 km up; the red comes from even higher, more like 300 km. There is barely any atmosphere at all at these altitudes.
Similar views were reported all over the planet. Aurora are usually restricted to very northerly latitudes, hence the moniker northern lights. A big CME floods the Earth’s magnetic field (and can distort it), leading to the appearance of aurora at lower latitudes. I had only seen them once before, in Ann Arbor in 1989, and then only as a ghostly grey wisp on the northern horizon. It takes a big event to produce colorful aurora overhead in Ohio.
It wasn’t just Ohio! Bright aurora were reported at all longitudes – I’ve seen lots of great pictures from Europe – to remarkably southerly latitudes, extending even to Florida and the Caribbean. This southerly reach is remarkable, but not uniform. One could see aurora overhead at the Apache Point Observatory in New Mexico, but they only appeared on the northern horizon at Kitt Peak in Arizona. Even that is an incredibly rare event!
Flares and CMEs have effects besides auroras – so much so that there is an entire field of space weather. The weather in space is particularly relevant to satellite operations, as big flares can blind or even damage sensors on satellites. It also affects their orbits. The radiation is also a hazard to would-be space travelers: you don’t want to get caught in a CME during a multi-month trip to Mars.
The sun is especially active right now. Usually rare, there have been multiple X-class flares. The space weather page sounds a bit exhausted, with stories like Region 3664 Remains Relentless and Another X-flare from Another Region! It seems a little like the weathermen they send to report on major storms by standing out in them for the entertainment of the audience. Only don’t try this in space.
Solar activity has not yet reached its peak, so hopefully we’ll get more opportunities to see aurora from the convenience of home.
Will wonders never cease? An eclipse in April, aurora in May; one could get spoiled: what will June bring? Hopefully not a Carrington level geomagnetic storm, which would make great aurora but the associated fluctuations in magnetic field would drive currents in electrical lines that could have an adverse effect on the power grid. Potentially very adverse. OK, maybe not that adverse, but I do appreciate having electricity.
*The atomic lines we see in aurora are from neutral oxygen, [O I] in the parlance of spectroscopy. This is strange to me, as I’ve worked on nebular spectra, where prominent emission lines are due to singly and doubly ionized oxygen – [O II] and [O III] in the parlance of spectroscopy. These lines thrive only in the extremely low density, practical vacuum of space (densities of tens or maybe hundreds of atoms per cubic centimeter), and were unknown in the laboratory when first observed astronomically. For a time, it was thought that, like helium in the sun, they represented a new element, nebulium – the stuff of which nebula were made.
Triton Station 
Those pictures of the Aurora in Ohio are spectacular. And the intensity of the color from your iphone with only a 3 second exposure was amazing. Unfortunately, I didn’t see anything here in southwest New Hampshire last Friday evening. But there’s nearby light pollution.
It must have been two 11 year cycles ago, or 2002 that I saw a similarly Aurora. I was leaving my job in Woods Hole, Massachusetts and walking between buildings. Immediately I noticed lights flickering overhead. I glanced up and was astounded to see a colorful Aurora in the narrow slot between the three story buildings. I raced to the guard desk and told them about it. Running as fast as I could to the parking lot I got in my car and headed for Surf Drive beach, which has a bike path running parallel to the Vineyard Sound. I ran along the path a good distance from the nearest street light and was treated to an awesome spectacle. Literally, half the sky was draped with streamers of red and green light. I stayed there quite a while. Have never seen anything like it since.
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I forgot to mention that there was one other aurora display that I witnessed, prior to the one above. Not sure of the year, but I was sleeping on the screened in porch of my brother’s old house in Rindge, NH, when I awoke at about 1 AM due to light from outside. I looked out the nearby windows and was astounded to see the bottom of the cloud deck lit up in a garish red color that pulsated. I was alarmed as it was a rather apocalyptic sight, and I wondered if a nuclear war had started. I walked out on the open part of the deck for a better view and soon concluded it was the aurora illuminating the clouds. My brother’s house was deep in the woods on top of a hill with virtually no light pollution, so perfect for sky gazing.
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Both of your experiences sound fantastic. It certainly helps to have a dark sky. So many of us live under so much light pollution, we literally have no idea what we’re missing.
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your attention for
arXiv:2405.10019 (astro-ph)
[Submitted on 16 May 2024]
Anomalous radial acceleration of galaxies and clusters supports hyperconical modified gravity
Robert Monjo, Indranil Banik
arXiv:2405.10019
arXiv:2405.08557 (astro-ph)
[Submitted on 14 May 2024 (v1), last revised 15 May 2024 (this version, v2)]
Galaxy clusters in Milgromian dynamics: Missing matter, hydrostatic bias, and the external field effect
Ruth Kelleher, Federico Lelli
arXiv:2405.08557
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1957/‘58. The International Geophysical Year. It seemed like there were science stories everywhere. In school we got our “Weekly Reader” that outlined stories of the science being conducted. And our parents also followed them and made sure we were aware. My father took us outside to watch a lunar eclipse and a tiny light called Sputnik as it sped past. There were stories about the sun (and its future fate) that made me pray that its demise occurred while we were on the night side, so we’d have enough warning to head for the basement. But, the topper was the two weeks we spent camping among the abandoned buildings of a ‘ghost town’ on the south shore of Lake Superior. We caught frogs, snakes, turtles, and fish. At night we watched the bears from the safety of our car as they searched the local dump for discarded food. And I’ll never forget the magic of the cascading colors of green and magenta that surged from the horizon above the lake at night. We just called them the Northern Lights. Our Grandmother, in her heavily accented English said, “they’re ok. But you should have seen them when I was a child in Norway.” My sister, now retired and living in Houghton, Mi. sent us magnificent photos from her i-Phone that seemed far more impressive than what we’d seen as children. Another sister living on Lake Huron also sent beautiful pictures. Unfortunately, where I live it was overcast.
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Awesome.
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Dear Stacy,
“AGC 114905 is a dwarf gas-rich ultra-diffuse galaxy seemingly “
Very nice answer. Really a very nice answer.
With dwarf galaxies, I feel like you’ve been everywhere.
And really importantly, I understood the answer.
Dark matter
You have convinced me of the non-existence of dark matter.
Perhaps you have convinced me more than you have convinced yourself.
I have never modeled or simulated anything with dark matter.
I have no emotional connection to dark matter
and don’t waste a thought on it.
Solar eclipse
I witnessed the solar eclipse in 1999 in southern Germany,
but was disappointed. The sky was cloudy and it didn’t get really dark,
dusky at best.
I have better memories of the Venus transit in 2012.
And of course the night sky in Namibia.
Work, family, home and research
It’s always difficult for two academics to find a job in the same city.
And it’s probably really hard for two professors.
It’s never perfect. Sometimes it’s not even good.
I was thrown out of the mainstream in the early 1990s.
I didn’t think it was that great at the time.
Today I enjoy it.
It has pros and cons.
Disadvantages: It’s hard for me to find people to talk to.
Advantage: If all the physicists are wrong, my thoughts aren’t poisoned by them.
are not poisoned by them.
An example: For many years, the German Wikipedia stated
that the special theory of relativity makes the ether obsolete.
Whenever I read something like that, it always took me about 10 minutes,
to recognize the nonsense in this sentence:
Mathematics always works without a material equivalent.
But we humans need an ether in order to better understand our world
and not just calculate it. An ether would explain
what light looks like and how it flies through a double slit.
Sometimes research, attending conferences, writing as many publications as possible
and YouTube feel like how the New York Stock Exchange is shouting.
Of course one can play along and achieve success.
But there is this old gentleman in Omaha (Nebraska) who has also been investing very well for 60 years…
How did Prof. David O. Edwards like to say elsewhere:
Science requires “taste and judgment”.
Thank you for your tolerance in this blog.
Stefan
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