Moonbow, Milky Way, meteor

By Phil Plait | October 21, 2012 7:00 am

If you’ve read this blog before, then all I really need to tell you is that Thierry Legault took a picture.

See?

While in Queensland, Australia, Thierry took this shot of Wallaman Falls. While the Milky Way shone down, a meteor zipped past, adding to the drama. But what’s that at the bottom? A rainbow? At night?

Yup. Well, kinda. It’s a Moonbow, the same thing as a rainbow but with the Moon as the light source. Well, and it’s not raindrops that cause it, but aerosolized water droplets acting as little prisms, breaking the light up into the usual colors. Moonbows are very faint, but they show up in long exposures like this one.

Leave it to Thierry to not be satisfied with just our galaxy, a bit of interplanetary debris vaporizing, and a waterfall in his shot. Amazing.

He has more pictures from that trip, and yeah, you want to see them. His photos have been on this blog so many times I can’t even list them, but check out the Related Posts below, click the links, then click the links at the bottom of those posts (or you can use my search engine). It’s a journey that’ll widen your eyes.

[UPDATE: Thanks to pixguyinburbank on Twitter, I learned of a wonderful video about moonbows put out by the folks at Yosemite National park in the US. It’s so good I’ll just add it here so you can see it. Fantastic!

Enjoy!]

Image credit: Thierry Legault, used by permission.


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CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (22)

  1. Mark

    You missed the “chemtrail” near the horizon ;-).

  2. Phil- Thanks for sharing the “Moonbows” episode of Yosemite Nature Notes!

    You might also like the newest episode called “Night Skies”

    http://www.youtube.com/watch?v=ZhgR3zVfo-0

    Featuring astronomers, Park Rangers and timelapse photographers, it took me nearly 3 years to finish this one.

  3. Robert

    Really? “Chemtrail”?

    Sigh.

  4. Ken

    But…but…I don’t see the silhouette of anything man-made in this picture! ;)

  5. Thanks Phil, the Thierry Legault photos are spectacular and both Steven Bumgardner videos are exceptional.

  6. MadScientist

    If the colored bow from your sprinkler in the daytime is a rainbow then yes, this is a moonbow. Personally I like to think of the moonbow as that giant colored bow in the sky produced from water droplets much higher up in the atmosphere rather than from a waterfall’s spray. Although I wouldn’t call this a moonbow, that’s one gorgeous photo.

  7. Randy Owens

    Wait… where’s the “click to X-ate” link to the bigger image? Where’s the real Bad Astronomer, and what have you done with him, you fiend?

  8. sailor

    It is interesting how bright that moonbow is. Maybe a factor of the amount of spray in the waterfall. When I have seen them in the rain on a full moon, the colors have been more muted and subtle.

  9. Dan

    Are we sure that’s a meteor in the picture, and not a plane? Given that the exposure on this pic took awhile (look at how the stars and waterfall have blurred), I wouldn’t have thought that a meteor would show up that well and yet still be in frame. Ah well. Even if it’s not a meteor, this photo could hardly be more awesome. Thanks for sharing!

  10. Zyggy

    I have always disliked the term “moonbow”. It is descriptive, but inconsistent.

    I mean, we don’t call the ones during the daytime a “sunbow”, do we? They’re rainbows. So these are rainbows also, just night time rainbows.

    Perhaps it should be a waterfallbow…then again, no, definitely not that. I’m open to suggestions.

    Not to rain on your parade, Phil. You didn’t coin the term. Thanks for the cool images. =)

    ~Zyg

  11. Dedalus

    I thought “moonbows” referred to misty (mistical?) rings around the full moon (???)

  12. Calinthalus

    I live near Cumberland Falls. Moonbows (Lunar Rainbows) are quite common. Here’s a good pic:
    http://tinyurl.com/9zow8ga

    Sure, I have to put up with Creatotards and other Bible Beaters…but things like Cumberland Falls and Mammoth Caves makes up for it.

  13. Roberto

    Da da da da da da da da moonbow
    Da da da da da da da da meteor
    moonbow meteor, moonbow meteor
    Milky Way Milky Way Milky Way meteor

  14. Teacher Al

    Oh, for gosh sakes, people. Moonbow is a really cool name. it trips off the lips like… something that trips easily off the lips. All this about consistency and prior use gets us nowhere as it’s not a “scientific” term and it’s just plain nifty. Geez.

  15. Thierry Legault

    Thank you for your nice comments!

    @Dan: yes it’s a meteor, I saw it visually and it was quite bright, fortunately it happened just during an exposure and in the right direction.

  16. Matt B.

    Isn’t a moonbow the thing that the goddess Selene used for hunting? (Kidding.)

    Ziggy (@10) is right. The nomeclature is inconsistent. It’s a lot like science fiction authors using the term “astrogator” in place of “navigator”, even though the latter refers to ships, not seas. By comparison, an astrogator would be someone that determines where to move a star.

    Likewise a moonbow would be a differential refraction of white light caused by the moon.

  17. MadScientist

    @sailor#8: I suspect the apparently muted color is a matter of perception. You’re looking at a photograph which has collected photons for an extended period vs. your eye’s receptors collecting such a low number of photons that the color receptors aren’t working at their best.

  18. If you’ve read this blog before, then all I really need to tell you is that Thierry Legault took a picture.

    Heh, well put! That is indeed all that needs to be said, and it’s a marked understatement as always. Not unlike saying “So yeah, Leonardo da Vinci painted a picture of some lady…” :)

    His photos have been on this blog so many times I can’t even list them, but check out the Related Posts below, click the links, then click the links at the bottom of those posts (or you can use my search engine). It’s a journey that’ll widen your eyes.

    You might also point out the tags at the very end of the post, including one under Mr. Legault’s name (just click it). That’d probably be the quickest way for folks to see all BA posts with his images…

  19. @ ^ Joseph G. Seconded by me. :-)

    Love this superluminous image. Cheers BA & Thierry Legault. :-D

    @14. Teacher Al : Agreed. I like the “moonbow” term – its poetic, descriptive and distinguishes it from normal “natural spectroscopes” ie. rainbows! :-)

  20. Mark

    Robert: I was kidding about the “chemtrail”, hence the ;-)

  21. Nigel Depledge

    Sailor (8) said:

    It is interesting how bright that moonbow is. Maybe a factor of the amount of spray in the waterfall. When I have seen them in the rain on a full moon, the colors have been more muted and subtle.

    This is probably a result of the long exposure time. Note the length of the star trails. It’s gotta be at least a 5-minute exposure.

  22. Thierry Legault

    It’s a 45-second exposure ;-)
    The lens is a 14mm f/2.8 on Canon 5D mark II.

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