YouTube: Sonic Boom Meets Sun Dog

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bystander
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YouTube: Sonic Boom Meets Sun Dog

Post by bystander » Thu Feb 18, 2010 1:34 am

Click to play embedded YouTube video.
Pay special attention at about 1:50
beachton123 wrote:Solar Dynamics Observatory Launch, Feb 11, 2010 HD VERSION A sun dog is a prismatic bright spot in the sky caused by sun shining through ice crystals. The Atlas V rocket exceeded the speed of sound in this layer of ice crystals, making the shock wave visible from the ground. The announcer can be heard in the video saying, "The vehicle is now supersonic."

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geckzilla
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Re: YouTube: Sonic Boom Meets Sun Dog

Post by geckzilla » Thu Feb 18, 2010 11:01 am

Wow, that looks so fake. I've never seen a sonic boom before. They really look like that? Pretty amazing.
Just call me "geck" because "zilla" is like a last name.

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Re: YouTube: Sonic Boom Meets Sun Dog

Post by RJN » Thu Feb 18, 2010 7:00 pm

Hi res image of the spherical shock:
http://www.flickr.com/photos/neurostar/ ... 288251657/
Copyright: George Privon
(Right click and isolate image to see the whole thing.)

Image

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RJN
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Re: YouTube: Sonic Boom Meets Sun Dog

Post by RJN » Thu Feb 18, 2010 7:06 pm

Is the spherical shock really caused by the sonic boom? Anyone have a feeling for this?

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neufer
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Re: YouTube: Sonic Boom Meets Sun Dog

Post by neufer » Thu Feb 18, 2010 7:20 pm

I once had a cocker spaniel that could travel even faster than that away from booms.
Art Neuendorffer

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Chris Peterson
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Re: YouTube: Sonic Boom Meets Sun Dog

Post by Chris Peterson » Thu Feb 18, 2010 7:22 pm

RJN wrote:Is the spherical shock really caused by the sonic boom? Anyone have a feeling for this?
It seems reasonable to me. I don't think it's spherical, though. The shock wave behind the rocket should be conical. From a single rear viewpoint, it would be hard to tell the difference.
Chris

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RJN
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Re: YouTube: Sonic Boom Meets Sun Dog

Post by RJN » Thu Feb 18, 2010 7:55 pm

Thanks, Chris! I played the movie several times trying to see if the shock front projections appeared (2D) circular or parabolic. It is hard to tell, but the top part appears somewhat circular. I would expect a conical shock wave to appear parabolic from off to the side, as the projection of a cone onto a vertical plane is a parabola. Any thoughts on that?

Anyway, I see that several other major astronomy sites have picked up on this. These include:

UT: http://www.universetoday.com/2010/02/11 ... y-the-sun/
NA: http://noisyastronomer.com/2010/02/11/sdo-is-go/
BA: http://blogs.discovermagazine.com/badas ... y-the-sky/

Phil Plait at BA notes that the shockwave annihilates the sun dog! I didn't notice that at first, but it does seem to occur.

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Re: YouTube: Sonic Boom Meets Sun Dog

Post by Chris Peterson » Fri Feb 19, 2010 4:46 am

RJN wrote:Thanks, Chris! I played the movie several times trying to see if the shock front projections appeared (2D) circular or parabolic. It is hard to tell, but the top part appears somewhat circular. I would expect a conical shock wave to appear parabolic from off to the side, as the projection of a cone onto a vertical plane is a parabola. Any thoughts on that?
My thinking is that the path of the rocket is through a fairly thin cloud layer, and substantially perpendicular to that layer. So regardless of viewpoint, what we are seeing is the intersection of a horizontal plane (the cloud layer) with a cone. Because the rocket is moving upwards, with its shock cone trailing, the shock appears as a circle of increasing diameter.
Chris

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PhysOrg: SDO Destroys a Sundog (w/3 Videos)

Post by bystander » Fri Feb 19, 2010 8:35 pm

Cool Movie: SDO Destroys a Sundog (w/ Video)
PhysOrg Space Exploration - 2010 Feb 19
SDO is designed to amaze — and it got off to a good start.

Videos by Anna Herbst, Romeo Durscher, and Barbara Tomlinson.