<p>The WISPR instrument is a visible light imager. You're right that it doesn't have a narrow depth of focus; it is basically focused at infinity. The video says we are seeing streams of plasma. The actual structures of these streamers are roughly parallel tubes projecting outward from the Sun, like a handful of dry spaghetti. We are seeing visible sunlight, shining onto the streamers and getting Thompson-scattered back to WISPR.</p>
<p>So the image shows a collection of these streamers, some close to the spacecraft (appearing broad and more diffuse) as well as farther away (appearing thinner). This <a href="https://svs.gsfc.nasa.gov/14045" rel="nofollow noreferrer">NASA page</a> gives some more info about the spacecraft's passage by the streamers that are shown in the still from the video you posted.</p>
<p>My guess is that you get the 2D effect from streamers appearing at the right distance: streamers too close appear blurred and uniform, while streamers too far are blended together into a uniform background. An analogy would be when you're in a snowstorm, and you can perceive snowflakes falling at an ideal distance away from you.</p>
<p>I was intrigued by the &quot;curved spaghetti&quot; artifact in the upper left panel of the still frame, so after watching <a href="https://www.youtube.com/watch?v=yaihZ7ZS2Ew" rel="nofollow noreferrer">a similar but more science-packed NASA video</a> on Parker results, I talked to an outreach specialist from NASA Goddard. She was able to pass along the following explanation from a solar scientist on the Parker Solar Probe mission:</p>
<blockquote>
<p>The curved streaks at 3:06 in this movie look like many of the other
impact ejecta we see when a dust particle hits the spacecraft and
ablates material. We can't state definitively what the origin of any
particular streak is, but it is highly likely that this curved streak
is an impact ejecta particle. The diffuse appearance of the streak is
likely because it is close to WISPR (thus out of focus).</p>
</blockquote>
<p>I had assumed that the very-straight thin lines in the images were direct cosmic ray hits on the detectors, like what we see with space telescope data. I was astounded to realize that this is &quot;ablation,&quot; or bits of the spacecraft shielding being knocked into space and flying away (after collisions with interplanetary dust). The <a href="https://wispr.nrl.navy.mil/" rel="nofollow noreferrer">NRL page</a> and the <a href="https://doi.org/10.1007/s11214-014-0114-y" rel="nofollow noreferrer">Space Science Reviews paper</a> say that CMOS was selected over CCD for these detectors because they are more robust to damage from dust and high-energy particles... Now I see why!</p>

CC BY-SA 4.0
2021-12-15T22:58:00.973Z
Oh this is an absolutely marvelous answer, *thanks!* I love the analogy to seeing/resolving snowflakes only within a certain range, and for those that haven't had the experience, the experience of looking at raindrops might work. Is the one "curved spaghetti" you mention in the top left frame? If it turns out to be related to a switchback that would be great!
uhoh
CC BY-SA 4.0
2021-12-15T23:01:45.203Z
no problem !! ah yes, i edited to say that the "curved spaghetti" is the one in the upper left frame. even if it's not related to the switchbacks they mentioned in the other part of the video, it would be cool to know what makes that one streamer  curved but not the others.
giardia
CC BY-SA 4.0
2021-12-18T00:57:25.677Z
@uhoh - the curved spaghetti is not related to solar wind switchbacks after all. i edited the post to remove that speculation, and provide an expert's description of the feature. i also added a link to an unlisted NASA youtube video. the video may not be available for long (not sure), so check it out while you can! the new video also contains an amazing image of the "venus dust ring."
giardia
CC BY-SA 4.0
2021-12-18T22:17:32.297Z
[interesting answer](https://space.stackexchange.com/a/57241/12102) to *What are the moving particles that can be seen by the Parker Solar Probe?*
uhoh
CC BY-SA 4.0
2021-12-15T22:44:10.687Z
2021-12-18T00:55:13.103Z
2021-12-18T00:55:13.103Z
giardia
<p>The new NASA Goddard video <a href="https://www.youtube.com/watch?v=LkaLfbuB_6E" rel="noreferrer">NASA's Parker Solar Probe Touches The Sun For The First Time</a> shows <em>what looks like</em> they might be photographs of the solar wind.</p>
<p>I'm having a hard time understanding how such clear 2D images can be taken of a 3D volume effect. I see high contrast bright and dark streaks and other structures as if a 2D slide was taken, but the camera doesn't have a narrow depth of focus on large scales and I assume these are kilometer or larger structures.</p>
<p>So I'm confused by these images.</p>
<p><strong>Question:</strong> How did Parker Solar Probe take what looks like 2D cross-sections of the solar wind in photographs? How can we see high contrast streaks &quot;in focus&quot; from a presumably volume effect?</p>
<p><a href="https://i.sstatic.net/C6iR3.jpg" rel="noreferrer"><img src="https://i.sstatic.net/C6iR3.jpg" alt="screenshot from the new NASA Goddard video &quot;NASA's Parker Solar Probe Touches The Sun For The First Time&quot;" /></a></p>

CC BY-SA 4.0
2021-12-15T07:54:04.050Z
I don't think these images are necessarily depicting large scale structures; upon viewing the video available at https://wispr.nrl.navy.mil , I kind of get the impression that the streaks are the results of Thomson scattering or a charged particle interacting with the CCD? Not 100% sure though
Justin T
<the-sun><photography><stellar-astrophysics><solar-wind><parker-solar-probe>
How did Parker Solar Probe take what looks like 2D cross-sections of the solar wind in photographs; high contrast streaks in focus from volume effect?
uhoh
# How did Parker Solar Probe take what looks like 2D cross-sections of the solar wind in photographs; high contrast streaks in focus from volume effect?

(Asked by: username_0 on 2021-12-14)

The new NASA Goddard video [NASA's Parker Solar Probe Touches The Sun For The First Time](https://www.youtube.com/watch?v=LkaLfbuB_6E) shows *what looks like* they might be photographs of the solar wind.

I'm having a hard time understanding how such clear 2D images can be taken of a 3D volume effect. I see high contrast bright and dark streaks and other structures as if a 2D slide was taken, but the camera doesn't have a narrow depth of focus on large scales and I assume these are kilometer or larger structures.

So I'm confused by these images.

**Question:** How did Parker Solar Probe take what looks like 2D cross-sections of the solar wind in photographs? How can we see high contrast streaks "in focus" from a presumably volume effect?

[![screenshot from the new NASA Goddard video ](https://i.sstatic.net/C6iR3.jpg)](https://i.sstatic.net/C6iR3.jpg)

**Tags:** the-sun, photography, stellar-astrophysics, solar-wind, parker-solar-probe
> **Comments:**
> **username_1**: I don't think these images are necessarily depicting large scale structures; upon viewing the video available at https://wispr.nrl.navy.mil , I kind of get the impression that the streaks are the results of Thomson scattering or a charged particle interacting with the CCD? Not 100% sure though  

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## 1 answers

### Answer by username_2 on 2021-12-15. Score: 4

The WISPR instrument is a visible light imager. You're right that it doesn't have a narrow depth of focus; it is basically focused at infinity. The video says we are seeing streams of plasma. The actual structures of these streamers are roughly parallel tubes projecting outward from the Sun, like a handful of dry spaghetti. We are seeing visible sunlight, shining onto the streamers and getting Thompson-scattered back to WISPR.

So the image shows a collection of these streamers, some close to the spacecraft (appearing broad and more diffuse) as well as farther away (appearing thinner). This [NASA page](https://svs.gsfc.nasa.gov/14045) gives some more info about the spacecraft's passage by the streamers that are shown in the still from the video you posted.

My guess is that you get the 2D effect from streamers appearing at the right distance: streamers too close appear blurred and uniform, while streamers too far are blended together into a uniform background. An analogy would be when you're in a snowstorm, and you can perceive snowflakes falling at an ideal distance away from you.

I was intrigued by the "curved spaghetti" artifact in the upper left panel of the still frame, so after watching [a similar but more science-packed NASA video](https://www.youtube.com/watch?v=yaihZ7ZS2Ew) on Parker results, I talked to an outreach specialist from NASA Goddard. She was able to pass along the following explanation from a solar scientist on the Parker Solar Probe mission:

> The curved streaks at 3:06 in this movie look like many of the other
> impact ejecta we see when a dust particle hits the spacecraft and
> ablates material. We can't state definitively what the origin of any
> particular streak is, but it is highly likely that this curved streak
> is an impact ejecta particle. The diffuse appearance of the streak is
> likely because it is close to WISPR (thus out of focus).

I had assumed that the very-straight thin lines in the images were direct cosmic ray hits on the detectors, like what we see with space telescope data. I was astounded to realize that this is "ablation," or bits of the spacecraft shielding being knocked into space and flying away (after collisions with interplanetary dust). The [NRL page](https://wispr.nrl.navy.mil/) and the [Space Science Reviews paper](https://doi.org/10.1007/s11214-014-0114-y) say that CMOS was selected over CCD for these detectors because they are more robust to damage from dust and high-energy particles... Now I see why!

> **Comments:**
> **username_0**: Oh this is an absolutely marvelous answer, *thanks!* I love the analogy to seeing/resolving snowflakes only within a certain range, and for those that haven't had the experience, the experience of looking at raindrops might work. Is the one "curved spaghetti" you mention in the top left frame? If it turns out to be related to a switchback that would be great!  
> **username_2**: no problem !! ah yes, i edited to say that the "curved spaghetti" is the one in the upper left frame. even if it's not related to the switchbacks they mentioned in the other part of the video, it would be cool to know what makes that one streamer  curved but not the others.  
> **username_2**: @uhoh - the curved spaghetti is not related to solar wind switchbacks after all. i edited the post to remove that speculation, and provide an expert's description of the feature. i also added a link to an unlisted NASA youtube video. the video may not be available for long (not sure), so check it out while you can! the new video also contains an amazing image of the "venus dust ring."  
> **username_0**: [interesting answer](https://space.stackexchange.com/a/57241/12102) to *What are the moving particles that can be seen by the Parker Solar Probe?*  

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