The green fire of the southern lights

By Phil Plait | June 20, 2010 5:12 pm

Check this out! The aurora australis — the southern lights — snakes its way across the Earth’s magnetic field as seen from above!

ISS_aurora_australis

Wow, that’s slick. It was taken on May 29th by an Expedition 23 astronaut aboard the International Space Station (it’s unknown which one; NASA and the astronauts decided to give the expedition the credit, not an individual crew member). At that moment, the ISS was 350 km (190 miles) above the Indian ocean, and the astronaut was looking south. You can see the limb of the Earth and some stars in the background as well. Click the picture to get a bigger version with more detail.

This aurora was probably caused by subatomic particles from an explosive event called a coronal mass ejection from the Sun five days earlier. The particles interact with our magnetic field, which channels them to the north and south poles. They slam into the air, ripping electrons off the atoms and molecules. When the atoms recombine, they give off light. The green glow seen here is characteristic of oxygen.

The aurorae are usually between 80 – 160 km (50 – 100 miles) above the Earth’s surface, so the ISS was actually higher up. However, the station was a couple of thousand kilometers away from the lights when this shot was taken.

I’ve only seen the northern lights (technically, the aurora borealis) once, when I lived in Maryland years ago… and it was just a faint red smear to the north. Someday I hope to see it in its full glory. But even then, it must pale — literally — to seeing such a thing from space.

Picture credit: NASA/Expedition 23

CATEGORIZED UNDER: Cool stuff, NASA, Pretty pictures
MORE ABOUT: aurora, Expedition 23, ISS

Comments (60)

  1. IVAN3MAN AT LARGE

    I saw that image earlier this evening at NASA’s Earth Observatory website, and I was beginning to wonder why you had not posted such a cool image.

  2. IVAN3MAN AT LARGE

    Hey, Phil, have you noticed how comments come flooding in during the weekdays, but not so much during the weekend? That’s probably because those individuals, who comment only on weekdays, are goofing off at work! ;-)

  3. pj

    Awesome.

    “When Kepler found his long-cherished belief did not agree with the most precise observation, he accepted the uncomfortable fact. He preferred the hard truth to his dearest illusions; that is the heart of science.”

    Dr. Carl Sagan quote

    @PJZen

  4. Ace

    So this is created as a result of subatomic particles interacting with the Earth’s magnetic field. As a result, are we able to see the boundary OF the magnetic field? That is to say, does the aurorae rest directly atop the magnetic field, highlighting it in a way?

  5. Allen

    Damn, that’s beautiful.

  6. Turns out that we have new tweeting astronaut on the ISS – and one of the first pics Doug Wheelock sent today was … another great aurora shot.

  7. Cairnos

    Made of Awesome!

  8. Anita

    Did you see this picture tweeted by Astro_Wheels? http://twitpic.com/1yh9e9
    I wonder if it is from the same occasion.

  9. NewEnglandBob

    Now we’re talkin’ STRIPES!

  10. LSandman24

    I forwarded this to my class as we are studying the Earth’s geomagnetic field this week. Good timing and happy dad’s day, Dr. Plait!

  11. Michael Kingsford Gray

    If the ISS is above the aurora, does that mean that these nasty particles are also intersecting the ISS? How do the crew guard against solar-flare-induced radiation hazards?

  12. Steph I

    I love all astronomy Apps and websites that are friendly to US that are not school taught but also that enjoy learning on our own time
    I have Starwalk App for my iPhone and I enjoy it as well as STEREO 3D the Solar App and a few others
    I love these NASA type fotos
    thanks

  13. Robin S.

    Beautiful!

    @ Michael Kingsford Gray (12): The ISS has a radiation hardened section to which the astronauts retreat if they are given warning of a hazardous solar event.

  14. Is the aurora blurry because it is moving? Or is that blur effect part of the interactions?

    It so amazing. And we are fortunate to live in such a time. Where we can see these wonders, even if we can’t be up in the space station in person, through the most vivid of pictures.

  15. Gary Ansorge

    4. Ace

    Charged particles orbit AROUND magnetic field lines, so what you’re seeing with this aurora is the result of particle interaction within the earths magnetic field.

    12. Michael Kingsford Gray

    I’m pretty sure the ISS orbits between van Allen belts, (and in those “dead” spaces they’re not exposed to much particle radiation). The same should be true of the aurora, since the energetic particles are guided into the earths atmosphere, where they do their damage. Of course, we don’t build our space craft of heavy metals anymore, because such metals are prone to liberating x-rays when they’re bombarded with charged particles. Instead the particles zip right thru the walls and the critters inside, w/o doing much damage.

    Gary 7

  16. Magnus T

    Another great southern lights by Wheelock yesterday:

    https://twitter.com/Astro_Wheels/status/16625431653

  17. @ 4. Ace,

    Well, I wrote up a reply expanding on Gary 7′s comment, but then edited it and it got caught in the spam filter. Until it shows up, here’s the short version:

    The boundary of the Earth’s Magnetic field is called the magnetopause and is much further out than the aurora. The latitude of the aurora does tell us something about the Earth’s magnetic field (ie, where the field lines are connected to, click my name for image), but the altitude of the aurora just depends on how puffy the atmosphere is.

  18. DrFlimmer

    [hoax mode=on]
    FAKE! How can there be stars in the background? Whenever you take a photo of the dark night sky you need quite long exposures! And that aurora should be fairly bright as well! Even on the moon we had no stars! Thus, the stars are photoshopped! The whole picture is photoshopped! The whole ISS-thing does not even exist!
    [hoax mode=off]

    I think, I am not good at such things ;)

  19. Messier Tidy Upper

    Magnificent image! Love it. This has got to be in your 2010 top ten surely! :-)

    Good to see our Sun is firing up again. I take it that this a sign of the new solar cycle building up from minima towards a crescendo and no longer being as unnervingly quiet as it has been?

    @ 14. Robin S. Says:

    Beautiful! @ Michael Kingsford Gray (12): The ISS has a radiation hardened section to which the astronauts retreat if they are given warning of a hazardous solar event.

    They do? I don’t recall hearing /reading about that. Do you happen to know which module it is in and if they have had to use it yet?

    @2. IVAN3MAN AT LARGE : Speaking from experience there are you? ;-)

  20. Jeff

    Get up to Fairbanks sometime in the next year or 2- the odds are better than average of getting a good show.

  21. Szwagier

    A cracker of an image.

  22. A Reader

    Not sure if this the same aurora? Twitter pic by @Astro_Wheels (Doug Wheelock on ISS) http://twitpic.com/1yh9e9

  23. @4. Ace,
    As @18 says, the aurora happens well within the Earth’s magnetic field, roughly at the point where the atmosphere becomes dense enough to efficiently absorb the energy of the precipitating electrons that cause the aurora. The electrons travel toward the Earth along the magnetic field, and if you look closely at the image you can see lots of short “spikes” nearly orthogonal to the auroral strip. These structures are aligned with the magnetic field, indicating its direction. They arise because of local variations in the intensity of the electron downpour, which translates to variations in local aurora intensity.

    @15. Non-Believer,
    Since the background is fairly crisp I would guess that the aurora is blurry because it moved during the long exposure (1/6th of a second, if I read the exif info correctly). But the aurora itself can also be diffuse, particularly the faint parts.

  24. Grand Lunar

    My new desktop background. :)

    Perhaps you should produce another book Phil, entitled “Beauty from the Skies”?

  25. Nigel Depledge
  26. Nigel Depledge

    To elaborate a little on what has already been said about the magnetic field and radiation …

    The Earth’s magnetic field extends a long way out. It is compressed on the day side of the Earth and hugely extended on the night side because of its interaction with the solar wind. Even so, the ISS orbits well within it all the time.

    Most of the radiation in the solar wind doesn’t get anywhere near the Earth’s atmosphere. When a CME hits the Earth dead-on, the magnetic field is compressed more and we get huge aurorae and very deep ionisation in the ionosphere, but we are still protected from the vast majority of the particulate radiation.

    IIUC, the aurora is the result, not of solar radiation impacting directly on the Earth’s atmosphere, but of particles from the sun that have been trapped in the magnetotail subsequently spiralling in towards the poles. IIUC (again), the Van Allen belts are charged particles that are trapped in the magnetic field, but I don’t know exactly how they relate to aurorae. Neither do I know how aurorae are triggered (something causes the magnetic field to flex and eject some of the particles from the magnetotail towards the Earth, but the details are obscure to me).

  27. Ryan The Biologist

    @DrFlimmer: I was actually wondering the same thing myself. It wouldn’t surprise me if the stars were photoshopped into that image to help the public understand what they were seeing.

    Aside from the likely alterations, it’s a very beautiful photo.

  28. Wow. At first I thought this was a screenshot from Star Trek: First Contact, but the real story is much better. Thanks.

  29. Observer

    Beautiful. I have for a while tried to imagine what an emerald rainbow would look like (mentioned in Revelation 4:3)

  30. IVAN3MAN AT LARGE

    @DrFlimmer (#20),

    In order to seriously imitate a total crackpot, you need to use ALL CAPITALS and add a few spelling mistakes (deliberately) for good measure, and then end sentences with multiple exclamation marks interspersed with number ones; for example: !!!1!!11!1!!

    @Messier Tidy Upper (#21),

    I work from home via my computer, so I goof off in my own time! ;-)

  31. Charles Brandon

    When I was Stationed at Ft. Lewis, Washington. I saw the Northern Lights twice. and they were gorgeous. I’d love to see the southern lights. And then go into outer space and see them from there. Oh man that would be a trip and a half.

  32. Daniel

    I saw those same lights in Maryland! We were wondering why the sky was all red, and drove out to a field to check them out. Definitely a rare event to have them so far south!

  33. JoeSmithCA
  34. Messier Tidy Upper

    @28. Grand Lunar Says:

    My new desktop background. Perhaps you should produce another book Phil, entitled “Beauty from the Skies”?

    I second that suggestion – how many “Top 10 pictures of year X” has the BA done now? Surely almost enough for a book there already! (& you’ll just *have* to add the new M66 image you’ve just posted about too surely!) ;-)

    I think it’s time you wrote another book BA, I’ve read & re-read both of yours a lot already and am eager for more! ;-)

    Please? A “Best of BA blog & pictures” one would be a good idea methinks – I’d even be happy to give you some best thread suggestions if it helps! :-)

    @ 35. IVAN3MAN AT LARGE : Sounds ideal – but I bet its sometimes hard to get any work done though. ;-)

  35. Peter

    I might be mistaken, but I always thought that the reason you don’t see stars from the moon pictures is that they were taken during the day (relative to the moon), when light from the sun overpowers the much weaker light from the stars (e.g., you don’t see stars during the daytime on Earth, unless you’re in a deep enough pit that blocks out most sunlight). If you look at the above picture, it looks like it’s on the night side of Earth; therefore, no sunlight to overpower the star light, so they show up.

  36. Jake

    Holy crap it’s the lifestream. No, bad NASA! No summoning Meteor!

  37. IVAN3MAN AT LARGE

    Messier Tidy Upper (#39):

    Sounds ideal – but I bet its [sic] sometimes hard to get any work done though.

    Yep — too many tea/coffee breaks! ;-)

    Peter (#40):

    … I always thought that the reason you don’t see stars from the moon pictures is that they were taken during the day (relative to the moon),…

    Yep — it’s due to contrast. :cool:

  38. Brian Too

    That is potent, concentrated wonderful right there in that image!

    Even though we get lots of aurora in my northern home, they aren’t usually as dazzling as this. It’s more of a majestic experience from the ground.

  39. Roberto Ruth

    It crossed my mind while reading this, although a little off topic. I think “space”; as in the place the Earth floats about in, should be spelled with a capital…. at all times. I mean, we owe our existence to it do we not?

  40. miguel laka

    I thought I would let you know…I live in N Central NDAK and have seen some unbelievable spectacles of the “Northern Lights” All the colors and a crackling/humming sound with it seemingly right above you. If the time is right, during an active period, and you want a tour in remote NDAK with no light pollution, contact me. Will be really cool.

  41. Nigel Depledge

    Peter (40) said:

    I might be mistaken, but I always thought that the reason you don’t see stars from the moon pictures is that they were taken during the day (relative to the moon), when light from the sun overpowers the much weaker light from the stars (e.g., you don’t see stars during the daytime on Earth, unless you’re in a deep enough pit that blocks out most sunlight). If you look at the above picture, it looks like it’s on the night side of Earth; therefore, no sunlight to overpower the star light, so they show up.

    Yeah, that’s kind of it.

    In fact, it’s the exposure settings. On the moon, the Apollo astronauts were photographing brightly-lit objects and therefore needed a short exposure (or narrow aperture or slow film or some combination of the three). Exposing for the (really, really dim) stars from the sunlit side of the moon would cause all the foreground objects to be hideously overexposed, and possibly to fog that frame of the film completely.

    Since the aurora is faint, it takes a longer exposure (or wider aperture or higher ISO setting or some combination of the three) to get a decent shot of it. Since the aurora is a bit less faint than the stars, a few stars show up faintly in the shot, while the aurora shows up brightly.

  42. Nigel Depledge

    Brian Too (47) said:

    Even though we get lots of aurora in my northern home, they aren’t usually as dazzling as this. It’s more of a majestic experience from the ground.

    It’s possible that the photo was the result of several seconds’ exposure, which (if this was the case) would mean that the aurora is far brighter in this shot than it would appear by eye.

  43. that is the most beautiful sight in the world.
    i can’t even imagine seeing this from above like that. what an outstanding photo!

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