Highest-resolution images ever captured of the sun’s surface(smithsonianmag.com)
smithsonianmag.com
Highest-resolution images ever captured of the sun’s surface
https://www.smithsonianmag.com/smart-news/check-out-the-highest-resolution-images-ever-captured-of-the-suns-entire-surface-180985518/
140 comments
Thanks for the hi-res images.
I couldn't resist blending the visible with ultraviolet in Photoshop, here's the result: https://imgur.com/a/vRGav2d
I did a quick clean up of the hard edges, but didn't want to push pixels too much.
I couldn't resist blending the visible with ultraviolet in Photoshop, here's the result: https://imgur.com/a/vRGav2d
I did a quick clean up of the hard edges, but didn't want to push pixels too much.
While that is nice, I would love to see the combined image with the uv image colour shifted to blue or magenta. Almost as if we could see UV with our eyes
That might be cool, although those colours might clash with the orange sun. You should try it.
I did another image, this time I took a section near the edge, flattened it to make an horizon, changed colours & contrast until it resembles ocean waves. https://imgur.com/a/5wnJUiN
I did another image, this time I took a section near the edge, flattened it to make an horizon, changed colours & contrast until it resembles ocean waves. https://imgur.com/a/5wnJUiN
Here is the link to the full directory contents of uploaded images; including hi-res ~99MB versions.
https://eopro.esa.int/wp-content/uploads/2024/10/
https://eopro.esa.int/wp-content/uploads/2024/10/
Would be nice to have it in an HDR format if they have something beyond 8-bit in the raw data
Downloading the big ones is so slow even over a semi-decent connection, it feels like getting certain lowres images in 1995 over a modem :-) What a blast from the past!
https://eopro.esa.int/wp-content/uploads/2024/10/PHI_Visible...
https://eopro.esa.int/wp-content/uploads/2024/10/PHI_Visible...
Why does the border of the sun look so poorly antialiased in all of these? Are they doing some sort of postprocessing that would cause that?
I’d print and hang the ultraviolet one on my wall if it wasn't for the very rough edges. Dang.
You haven't developed a good taste in scientific art then. The jagged mosaic edges are, IMHO, the flourish of authenticity that completes it.
Rough edges—that's like rejecting a van Gogh painting because it has too much paint and looks lumpy[0]. Art is lumpy. The ones that are perfectly flat are inkjet prints.
[0] https://en.wikipedia.org/wiki/Impasto
Rough edges—that's like rejecting a van Gogh painting because it has too much paint and looks lumpy[0]. Art is lumpy. The ones that are perfectly flat are inkjet prints.
[0] https://en.wikipedia.org/wiki/Impasto
Here's a version with hard edges softened a bit, although my effort is a 5 min job, it scrubs up okay. Also this is a blend of visible and ultraviolet. Good old imgur, they allow massive jpeg uploads without needing to sign up or log in!
https://imgur.com/a/vRGav2d
https://imgur.com/a/vRGav2d
Btw any tip for a good printing service available in Europe if I were to mega-print this?
you can probably use any AI generator to fix it in the same color
Best looking image ever captured of the Sun's entire surface goes to:
https://x.com/AJamesMcCarthy/status/1638648459002806272
by
Andrew McCarthy: https://www.instagram.com/cosmic_background/
Jason Guenzel: https://www.instagram.com/thevastreaches/
https://x.com/AJamesMcCarthy/status/1638648459002806272
by
Andrew McCarthy: https://www.instagram.com/cosmic_background/
Jason Guenzel: https://www.instagram.com/thevastreaches/
For anyone that wants to buy the 139 megapixel image for printing, it's $50 here: https://cosmicbackground.io/products/fusion-of-helios
I'm not affiliated, but I've been seriously debating it for a long time. The photo is a composite of the sun and the sun's heliosphere from the 2017 eclipse. One of my favorite images of the Sun.
I'm not affiliated, but I've been seriously debating it for a long time. The photo is a composite of the sun and the sun's heliosphere from the 2017 eclipse. One of my favorite images of the Sun.
Do you think that is original or some AI enhanced copy of the twitter img?
It’s the original. Andrew McCarthy links to it from both his Twitter and Instagram accounts. It’s his own website.
Perhaps rr808 is referring to AI upscaling. As in, are these 139 proper megapixels or upreased to that size?
It's made from over 90,000 individual images that have been stitched/combined together. I'm not the original photographer so I can't comment on his process, but I think it would be silly to use upscaling (AI or otherwise) when your starting data set likely contains multiple gigapixels.
I am very tempted now
I have to imagine capturing an image over five days shows how static something is, not dynamic. Very confusing wording there! Great photo, though.
It's not quite a time lapse. They took 90000 images, but they will be selecting the sharpest and most interesting subset for each section of image, not just smearing them all together.
Maybe static vs. dynamic have different meanings when talking about celestial objects that are billions of years old, 864,000 miles across and a million times the size of the planet you're living on?
I agree! Very odd choice of words indeed. I wonder what semantics they were trying to convey.
That’s beautiful, but not really a photo of the sun. It’s heavily processed and digitally modified.
It’s still a photo of the sun, even if processed. You wouldn’t see much on an unprocessed photo of the sun..
What a disingenuous comment. It's not a generative AI image. It's not something someone drew/painted. It's photographic data combined together.
If you want to be pedantic, every single picture ever taken with a digital camera is digitally modified. Every single image shot on film and scanned to be used on a computer is digitally modified.
Just because you can't take a photo of the sun anywhere close to this does not mean others of us cannot, and does not make their actual images of the sun not real. Using proper filters so you do not melt your equipment allows for images of the photosphere to be captured. Using the moon to filter the photosphere during an eclipse allows the corona to be seen. It's not like it's not there except during an eclipse. It's just too faint to be captured without the filter.
That's what the SRO uses a cornograph to block the photosphere at all times to be able to image the corona.
Imaging the sun is very fun and challenging, and I'd suggest you'd learn a lot from reading up on it. Whether you'd actually enjoy it is beyond the scope of this forum
If you want to be pedantic, every single picture ever taken with a digital camera is digitally modified. Every single image shot on film and scanned to be used on a computer is digitally modified.
Just because you can't take a photo of the sun anywhere close to this does not mean others of us cannot, and does not make their actual images of the sun not real. Using proper filters so you do not melt your equipment allows for images of the photosphere to be captured. Using the moon to filter the photosphere during an eclipse allows the corona to be seen. It's not like it's not there except during an eclipse. It's just too faint to be captured without the filter.
That's what the SRO uses a cornograph to block the photosphere at all times to be able to image the corona.
Imaging the sun is very fun and challenging, and I'd suggest you'd learn a lot from reading up on it. Whether you'd actually enjoy it is beyond the scope of this forum
Sure, but they're not just combining, they're selecting for maximal artistic effect.
> A geometrically altered image of the 2017 eclipse as an artistic element in this composition to display an otherwise invisible structure. Great care was taken to align the two atmospheric layers in a scientifically plausible way using NASA's SOHO data as a reference.
https://cosmicbackground.io/products/fusion-of-helios
I mean, take a look at some of the photographers other work...
https://cosmicbackground.io/products/tales-from-the-solar-sy...
> A geometrically altered image of the 2017 eclipse as an artistic element in this composition to display an otherwise invisible structure. Great care was taken to align the two atmospheric layers in a scientifically plausible way using NASA's SOHO data as a reference.
https://cosmicbackground.io/products/fusion-of-helios
I mean, take a look at some of the photographers other work...
https://cosmicbackground.io/products/tales-from-the-solar-sy...
Okay and?
What do you mean, and? They're clarifying the original point, as was expressly requested in the parent comment. The image undoubtedly has some amount of "artistic freedom" taken. What threshold decides when an image becomes more art than science is a parameter that each person is free to decide for themselves. I think it's absolutely relevant to discussion to point out that there might be more "artistic freedom" in this image than most might believe, especially when the post is about photos of the sun of a much more scientific and exact nature.
My point is in what was is “well actually it’s not technically a photograph” helpful, interesting, or relevant contribution to discussion?
Great. It’s not strictly a graph of photons. Zero people are using this stitched together image to perform science. Moreover, virtually every single space image intended for public consumption has been converted from UV/radio/infrared into the visible spectrum, retouched, stitched together as a composite, or experienced some other form of artistic manipulation.
Nobody cares. Nobody should care. This is a thoroughly inconsequential hill to die on and a completely pointless bit of pedantry.
Great. It’s not strictly a graph of photons. Zero people are using this stitched together image to perform science. Moreover, virtually every single space image intended for public consumption has been converted from UV/radio/infrared into the visible spectrum, retouched, stitched together as a composite, or experienced some other form of artistic manipulation.
Nobody cares. Nobody should care. This is a thoroughly inconsequential hill to die on and a completely pointless bit of pedantry.
Twitter say "something went wrong", plus three dialogues consuming or obscuring something more than half the page.
Big fan of Andrew McCarthy's work, been following him on IG for a few years now. The stuff he's able to pull off as a backyard astrophotographer is very impressive.
Actual zoomable images here:
https://www.esa.int/Science_Exploration/Space_Science/Solar_...
Is this a solution they rolled on their own? Cause it's abysmal. I've seen Leaflet being used for gigapixel images and it's great, even if it seems unorthodox.
They're using OpenSeadragon hosted on a codepen.
https://openseadragon.github.io/
https://codepen.io/Kimtaro88/embed/JjgLyJg/ee2ebbe7041869032...
https://openseadragon.github.io/
https://codepen.io/Kimtaro88/embed/JjgLyJg/ee2ebbe7041869032...
Leaflet is actually listed at [1], I believe it's totally orthodox :-)
[1] https://en.wikipedia.org/wiki/International_Image_Interopera...
[1] https://en.wikipedia.org/wiki/International_Image_Interopera...
OpenSeadragon, the one they're using, is also listed there. First on the list.
While it works, the resolution is underwhelming and there's no scale.
The Sun's diameter is 109 times that of Earth, though you might as well round up to 110, or down to 100.
1.4 * 10^6 km vs. 14 * 10^3 km.
1.4 * 10^6 km vs. 14 * 10^3 km.
If you scroll down to the image carousel/gallery and click on an image, it directs you to a page where you can download a high-res jpeg (~100mb for the ultraviolet one).
The scale and violence of the processes that drive the Sun are really mind-blowing. 43 million km away and it's getting on for 20kW per square metre. Edit: the probe is that far from the sun.
Fun fact: if the Solar System had an atmosphere that stretched from the Sun to the Earth (at least) then the sound of the Sun from Earth would be ~100dB.
IIRC the Sun converts ~4.5 million tons of mass into energy every second and even then, there are objects that are trillions of times more energetic/violent. The first LIGO detection I believe converted 5 Solar masses into energy in about a second.
IIRC the Sun converts ~4.5 million tons of mass into energy every second and even then, there are objects that are trillions of times more energetic/violent. The first LIGO detection I believe converted 5 Solar masses into energy in about a second.
You just reminded me of https://spacesounds.com which I remember seeing in the very early 2000s and thinking it was awesome.
And 4.5 million tons of mass/second may be unimaginably huge, but the Sun is so big it can also do that constantly for literally billions and billions of years. And it's not even an especially big star!
And 4.5 million tons of mass/second may be unimaginably huge, but the Sun is so big it can also do that constantly for literally billions and billions of years. And it's not even an especially big star!
Do we have any idea what it would sound like?
Looking online I found this:
https://www.nasa.gov/solar-system/sounds-of-the-sun/
But it's not realistic because:
> Finally, he interpolated over the missing data and scaled the data (speeded it up a factor 42,000 to bring it into the audible human-hearing range (kHz)).
Also this:
https://www.youtube.com/watch?v=xAesteoeoF4
but it's not actually sound, it's converting EM waves into sound:
> ...recording frequency and amplitude information about these plasma waves that scientists can then play as sound waves.
So I'm really curious if the genuine sound of the sun would just be white noise, like a waterfall or rumble, or with defined frequences (hums), or if it's all so low-frequency or high-frequency or something that it isn't even audible?
Looking online I found this:
https://www.nasa.gov/solar-system/sounds-of-the-sun/
But it's not realistic because:
> Finally, he interpolated over the missing data and scaled the data (speeded it up a factor 42,000 to bring it into the audible human-hearing range (kHz)).
Also this:
https://www.youtube.com/watch?v=xAesteoeoF4
but it's not actually sound, it's converting EM waves into sound:
> ...recording frequency and amplitude information about these plasma waves that scientists can then play as sound waves.
So I'm really curious if the genuine sound of the sun would just be white noise, like a waterfall or rumble, or with defined frequences (hums), or if it's all so low-frequency or high-frequency or something that it isn't even audible?
One of the detections was of a merger that momentarily had a higher power output than the entire rest of the visible universe combined.
The scale/mass of the sun is just fascinating. It takes ~500,000 years for a photon released in the fusion process to escape the core. That's just how dense the core is that a photon gets bounced around that much. The fact that the outer layer (corona up to 3,500,000°F is so much hotter than the surface(photosphere around 10000°F) that is on top of the core (around 27,000,000°F) is just another one of those weird to appreciate as well.
For anyone else reading this comment in anywhere but the United States...
The Sun's surface/photosphere is 5,772 kelvins (commonly cited as ~6000 °C), the corona is in the order of magnitude of 1 million kelvin, and the core is around 15 million kelvin.
The Sun's surface/photosphere is 5,772 kelvins (commonly cited as ~6000 °C), the corona is in the order of magnitude of 1 million kelvin, and the core is around 15 million kelvin.
I think it's crazy how little impact this giant constantly exploding ball of turbulent plasma has on our day to day lives. We get consistent light and heat, and occasional auroras... and that's it? This thing has enough energy to wipe out every last trace of human existence.
otherwise we obviously wouldn't have been here.
When you think about it - 43 million kilometers away, and still nearly 20kW per square meter - that’s an immense amount of power
Only 20kw per square meter on the surface of the sun ? How come it is so low ?
We receive about 1kw of sunlight per square meter on Earth, and earth is 149M km from the sun. From napkin math, it should rather be ~45MW/sqm on the sun to receive 1kw/sqm on Earth (surface of the sphere of radius 149M km divided by surface of the sun gives ~45000, so 1 watt from the sun becomes 1/45000 watt when it reaches the Earth)
Where am I wrong ?
We receive about 1kw of sunlight per square meter on Earth, and earth is 149M km from the sun. From napkin math, it should rather be ~45MW/sqm on the sun to receive 1kw/sqm on Earth (surface of the sphere of radius 149M km divided by surface of the sun gives ~45000, so 1 watt from the sun becomes 1/45000 watt when it reaches the Earth)
Where am I wrong ?
Because that's the irradiance at the Solar Orbiter's closest approach (well, more like 17.5kW, hence getting on for).
It's pretty amazing that you can have a spacecraft in nearly 20x direct sunlight, permanently and still have it actually work.
It's pretty amazing that you can have a spacecraft in nearly 20x direct sunlight, permanently and still have it actually work.
Your calculations are incorrect. Use common sense, models, and first principles. Light point source irradiance is E = P/4πr², so inverse square law. It's 1361 W/m² at Earth's distance of 1.5e11 m. Solar Orbiter dips down to 4.2e10 m. ¼ the distance,
Total solar power output = 4 * π * (1.5e11 [m])² * 1361 [W] = 3.85e26 W/m²
Sun's "surface" irradiance = TSPO / (4 * π * (6.96e8 [m])²) = 6.32e9 W/m²
At Solar Orbiter's perihelion, assuming the distance from the Sun's point center rather than the Sun's surface = TSPO / (4 * π * (4.2e10 [m])²) = 1.74e4 W/m².
^ Except for Earth's irradiance and the distances, these are theoretical rough values rather than observed ones because reality is messier than simplified models.
Total solar power output = 4 * π * (1.5e11 [m])² * 1361 [W] = 3.85e26 W/m²
Sun's "surface" irradiance = TSPO / (4 * π * (6.96e8 [m])²) = 6.32e9 W/m²
At Solar Orbiter's perihelion, assuming the distance from the Sun's point center rather than the Sun's surface = TSPO / (4 * π * (4.2e10 [m])²) = 1.74e4 W/m².
^ Except for Earth's irradiance and the distances, these are theoretical rough values rather than observed ones because reality is messier than simplified models.
The real issue was that I didn't get that you were talking about Solar Orbiter, I thought you were saying that the irradiance of the sun was 20kW/m2, which seemed low to me, but I didn't even know the word "irradiance" so I didn't know what to type on Google to check it.
Thanks for your detailed calculus :)
It's basic algebra. Calculus would involve derivatives or integrals.
https://www.merriam-webster.com/dictionary/calculus
The usual sense involves integration and derivation but look at senses 2 & 4. It also means any calculation.
The usual sense involves integration and derivation but look at senses 2 & 4. It also means any calculation.
And that is in all directions!
[deleted]
> 43 million km away
er, 149 million km away [0] not 43
[0] https://en.wikipedia.org/wiki/Sun
er, 149 million km away [0] not 43
[0] https://en.wikipedia.org/wiki/Sun
The Solar Orbiter is 43 million km away from the Sun at its closest.
If we got 17.5ish kW per square metre here on Earth, you'd know about it (but only briefly).
If we got 17.5ish kW per square metre here on Earth, you'd know about it (but only briefly).
Hm, the article seems to have gotten its units wrong. Normally I'd trust the article but 43 million kilometers seems to match best with its orbit I can find documentation for.
I was wrong with my initial jumping to conclusions, but on inspection I see that the underlying ESA press release [0] actually says "The images were taken when Solar Orbiter was less than 74 million kilometres from the Sun". Now I'm really confused.
[0] https://www.esa.int/Science_Exploration/Space_Science/Solar_...
[0] https://www.esa.int/Science_Exploration/Space_Science/Solar_...
Presumably the images were taken on the way to perihelion. The orbit isn't circular, it's both highly eccentric and inclined relative to the ecliptic to get a view of the solar poles. A plane change is really hard on delta-v, so they tilt the orbit up bit by bit with repeated Venusian gravity assists. In the main science phase of the mission there are 14 planned perihelion approaches.
There's a diagram here, but at least some of the information there seems preliminary as they eventually launched with a black "Solar Black" heat shield coating rather than white titanium dioxide because the latter wasn't sufficiently UV-stable.
https://www.eoportal.org/satellite-missions/solar-orbiter-mi...
There's a diagram here, but at least some of the information there seems preliminary as they eventually launched with a black "Solar Black" heat shield coating rather than white titanium dioxide because the latter wasn't sufficiently UV-stable.
https://www.eoportal.org/satellite-missions/solar-orbiter-mi...
Well, they’re _technically_ correct.
Oops, my bad
grues-dinner was referring to the Solar Orbiter's distance from the Sun, and the intensity of radiation on the Orbiter.
Not the Sun's distance from Earth, and radiant intensity at the Sun's surface.
(The comment was unclearly worded and it took me a couple of readings and review of comments to realise the intent.)
Not the Sun's distance from Earth, and radiant intensity at the Sun's surface.
(The comment was unclearly worded and it took me a couple of readings and review of comments to realise the intent.)
The Sun is eldritch horror. The test of being human is being fine with it.
Have people wondered about a possibility of an advanced life form hiding inside a star? It doesn't seem easy, but there'd be an abundance of energy, and the less advanced life forms are unlikely to interfere.
I found the part about the possibility of life on neutron stars to be fascinating.
Then you will love "Dragon's Egg" by Robert L. Forward. https://en.wikipedia.org/wiki/Dragon%27s_Egg
Stanislaw Lem's short story "The Truth" https://thereader.mitpress.mit.edu/the-truth-by-stanislaw-le...
It’s also fun to think about how hard it would be for us to detect such life forms
The Saga of the seven suns has beings living in suns. Unsure how far they go with the idea,I'm missing 3 of the 7 books
Revelation space has got the Amarantin living has simulations inside a neutron star.
The Knights of the Sun
Stephen Baxter’s Flux has something in that vein
Define life!
You mean... like seriously?
I am puzzled by the « sun in visible light » picture: what is this # in the middle of it? (Physical phenomenom, or artifact from the pictures)
That's definitely an artifact from stitching multiple images. But I'm not sure why they would leave it that way since it's quite noticeable, but I guess there is always some debate on how much post-processing should they do on a scientific images and some people prefer closer to the raw capture even if it's not perfect.
Oh yeah, that is interesting. I would guess an artifact from the pictures. Maybe those are the lines where they joined the different pictures together into 1 picture. I would think they could do a better job than that though.
You can, somehow, view this # in the magnetic field map picture too. First I thought this was an artifact, but I highly doubt that they would leave such an amateur thing behind (and even amateurs don't get tricked into this). Besides from the visible picture and magnetic map, I don't seem to find any correlation with the other pictures.
> The process took more than four hours, since the spacecraft had to change position for each individual photograph. In the final mosaics, the sun’s diameter is almost 8,000 pixels across.
I'm guessing this is sort of equivalent to manual supersampling rather than combining adjacent (ie visually translated to the next subsquare of the photo) viewpoints? Four hours is a pretty short time for 48 million miles of distance.
Edit: well considering orbital velocity I guess they probably just zigzag'd perpendicular to the orbital plane?
I'm guessing this is sort of equivalent to manual supersampling rather than combining adjacent (ie visually translated to the next subsquare of the photo) viewpoints? Four hours is a pretty short time for 48 million miles of distance.
Edit: well considering orbital velocity I guess they probably just zigzag'd perpendicular to the orbital plane?
I will be avoiding looking at them directly so I don’t hurt my eyes
Is there no PNG or JPG? A lot of these space photos make nice backgrounds, but they're increasingly being displayed in weird zoomable only on a web page galleries
Displaying this would be a fun use of the Las Vegas Sphere.
"Resolution" is used very loosely here. They are very big images of the full Sun (in terms of the number of pixels), but there are also various telescopes that "zoom in" much more on a small part of the Sun, resulting in images with much higher details than the ones from this article.
How crazy is it that sun spots look like skin cancer, or skin cancer looks like sun spots.
I just found these videos by the Solar Orbiter, insane: https://www.youtube.com/watch?v=L00J3hZCdFs
I’m astounded by how plain and round the visible light images are. Why is the corona only visible in the UV images, if it is, according to the article, visible from earth?
Corona is very hot (millions of degrees) as opposed to 6000 of the Sun's surface, therefore it has higher contrast over Sun's surface if you go to shorter wavelengths. The reason corona is still visible from Earth is because it you mask the main solar disk (during the eclipse).
It might be that the surface is much brighter in visible light than the corona rather than the corona emits no visible light (as anyone who witnessed the recent total solar eclipse can attest). Since the corona is made up of rarefied high energy particles I would expect it to emit less total, but more short wavelength light.
I’m guessing they mask out the edges. Maybe for exposure reasons or something?
[deleted]
it’s wild that we have all this data but we don’t really know what any of this stuff actually is (celestial bodies overall not just the sun) only what radiations they give off that we can read and recognize, for all we know stars are the outer shell of a multidimensional being and the heat is just an effect of us not being able to ascend dimensionally in order to pass into it because it’s “above” spacetime and attempting to pass through means transcending into an eternal realm which we of course would be vaporized because our matter is in this dimension, or it could be (insert anything, we may never know!)
Every time I learn something new about the Sun or see photos like this it makes sense we used to worship it (and maybe we should bring that back.)
Sometimes I stand in the sun and feel it as hot as a nearby oven on my skin. Then I consider that I'm receiving about 1e-24 of its radiant energy. I don't blame our ancestors!
It's truly awe inspiring to know how inconceivably huge and far away the Sun is, yet it we can feel it's warmth, admire how it's light touches everything we see, and how it's responsible for all life on Earth. I love our star :)
How do they picture the magnetic field from far away like this? I would have thought that the probe can only sense the local field.
Cool. BTW, the sun shines white, not yellow.
Sunspots and the visible dynamics around them are always so mesmerizing
> Highest-resolution images ever captured of the sun’s entire surface
Did the probe revolves around sun ?
Did the probe revolves around sun ?
Firstly the Sun itself rotates roughly once a month, and secondly if the probe wasn't going round the sun, it would be called the Solar Impactor, not the Solar Orbiter. Or maybe the Solar Evaporated Slag Cloud when it got close enough.
Well it could also be in the Sun’s equivalent of a geostationary orbit. If ChatGPT is not making things up this would be around 60 million km which is quite feasible.
It's quite difficult with current rocket technology: you have to counteract most of the Earth-given 30km/s speed around the Sun in order to get close (it's smaller than Mercury's orbit), and then brake again to circularize the orbit once you are there. I am not sure that it can be done with what we have now. That said, it's not that far off either.
There's also no such thing as a single heliosynchronous orbit, because different latitudes of the Sun rotate at different speeds. So an orbit which keeps a point on the equator (25 day period) under it would see the polar regions (36 days) rotating backwards. Every three equatorial rotations or so, you'd "lap" the polar region, which would only make 2 rotations in that time.
I guess ChatGPT is making things up because it is much less than that. Closer to 25million km, although complicated by the fact that the sun does not rotate as a rigid body but instead rotates faster at the equator than the poles.
I just wanted to say I appreciate every single one of your comments on this thread but this one even more so
I thought it would be cool as a wallpaper so I added a bit of blur to it, pretty fun: https://photoshop.adobe.com/id/urn:aaid:sc:US:1779ee13-d89c-...
"Surface" is quite a bit of statement.
Yep, it's a big orange ball.
I thought Sol was basically white? very yellow/orange in the left-most image.
We typically define the Sun to be white, but it has an interesting spectrum. White is just "all of the colors" and the Sun happens to be the object providing most of our light. In a very real sense, we try to make light bulbs "Sun colored."
This image is colored because it uses a red filter:
> The instrument collected red light with a wavelength of 617 nanometres.
One last thought, because I think it's fun. The Sun looks yellow to us on Earth because the sky is blue. Think about it.
https://en.wikipedia.org/wiki/Standard_illuminant
https://ars.els-cdn.com/content/image/1-s2.0-B97804431878650...
This image is colored because it uses a red filter:
> The instrument collected red light with a wavelength of 617 nanometres.
One last thought, because I think it's fun. The Sun looks yellow to us on Earth because the sky is blue. Think about it.
https://en.wikipedia.org/wiki/Standard_illuminant
https://ars.els-cdn.com/content/image/1-s2.0-B97804431878650...
Indeed, good qstn.
The sun is emitting light at roughly the spectrum curve of a (non-ideal) black body at 5778°K [1].
The 'black body' curve is the idealized electromagnetic spectral emission curve of how every body 'glows' according to temperature. [0] The peak of the sun's emission curve is around 500nm which is a blue-green, but of course it is spread out across a broad spectrum so is closer to white, and then it is differentially scattered by the atmosphere.
But these photos have no atmospheric filtering or scattering, so, perhaps the yellow-orange hue is more related to their own filters?
[0] https://en.wikipedia.org/wiki/Black-body_radiation
[1] https://physics.stackexchange.com/questions/130209/how-can-i...
The sun is emitting light at roughly the spectrum curve of a (non-ideal) black body at 5778°K [1].
The 'black body' curve is the idealized electromagnetic spectral emission curve of how every body 'glows' according to temperature. [0] The peak of the sun's emission curve is around 500nm which is a blue-green, but of course it is spread out across a broad spectrum so is closer to white, and then it is differentially scattered by the atmosphere.
But these photos have no atmospheric filtering or scattering, so, perhaps the yellow-orange hue is more related to their own filters?
[0] https://en.wikipedia.org/wiki/Black-body_radiation
[1] https://physics.stackexchange.com/questions/130209/how-can-i...
No, Sol does not output equally across the spectrum. I'm assuming this is artificially colored on some level, though.
Not colored, but filtered. At least for the specific "orange" image. The other images are since they're different types of sensors.
If you view the sun with eclipse glasses, you basically see the "orange" image just with your eyes. Add the same level of filtering to a telescope or long lens on your camera, and you can capture similar image.
If you view the sun with eclipse glasses, you basically see the "orange" image just with your eyes. Add the same level of filtering to a telescope or long lens on your camera, and you can capture similar image.
As you mention, the leftmost image (the red "photogram" intending to show intensity) is filtered. I'm writing mostly to amplify your comment because I spent some years working with these images.
People may not be aware how strongly filtered it is. The PHI imager is using 6 very narrow (<<0.1 nm) passbands, all centered about one absorption line (Fe I, 317nm, as you mention). It's insanely narrowband.
From the abstract of the paper (https://arxiv.org/pdf/1903.11061) describing the instrument:
> SO/PHI measures the Zeeman effect and the Doppler shift in the Fe i 617.3 nm spectral line. To this end, the instrument carries out narrow-band imaging spectro-polarimetry using a tunable LiNbO3 Fabry-Perot etalon, while the polarisation modulation is done with liquid crystal variable retarders (LCVRs). The line and the nearby continuum are sampled at six wavelength points and the data are recorded by a 2k × 2k CMOS detector. [...] The high heat load generated through proximity to the Sun is greatly reduced by the multilayer-coated entrance windows to the two telescopes that allow less than 4% of the total sunlight to enter the instrument, most of it in a narrow wavelength band around the chosen spectral line.
(Note: the 4% figure is just the pre-filtering at the entrance window, before the even sharper filtering done by the etalon.)
So the image you see is just a reconstruction of intensity using the 6 extremely narrow filters (I'm not sure precisely how they do the reconstruction; an analogous NASA instrument called HMI uses the straight average IIRC).
So, the remarks nearby about the black body emission of the Sun, etc., are correct but not relevant to the color used. The red color is just as easily viewed as the traditional coloring used for the scalar intensity represented by this image type, kind of mnemonically related to the fact that the FeI line at 617nm is in the red wavelengths.
In writing journal papers using these images, sometimes people use the longer but techically correct "pseudo-continuum intensity image" rather than the punchier "photogram". This emphasizes that the image shown is a reconstruction of the continuum intensity.
And as you say, the other "images", including magnetic field and velocity, are reconstructed using other algorithms from these 6 wavelengths. For instance, velocity is recovered because the Fe-I absorption line's location shifts with Doppler velocity along line-of-sight.
And magnetic field is recovered due to the Zeeman effect on the line shape.
It's amazing what you can do when you have so many photons!
People may not be aware how strongly filtered it is. The PHI imager is using 6 very narrow (<<0.1 nm) passbands, all centered about one absorption line (Fe I, 317nm, as you mention). It's insanely narrowband.
From the abstract of the paper (https://arxiv.org/pdf/1903.11061) describing the instrument:
> SO/PHI measures the Zeeman effect and the Doppler shift in the Fe i 617.3 nm spectral line. To this end, the instrument carries out narrow-band imaging spectro-polarimetry using a tunable LiNbO3 Fabry-Perot etalon, while the polarisation modulation is done with liquid crystal variable retarders (LCVRs). The line and the nearby continuum are sampled at six wavelength points and the data are recorded by a 2k × 2k CMOS detector. [...] The high heat load generated through proximity to the Sun is greatly reduced by the multilayer-coated entrance windows to the two telescopes that allow less than 4% of the total sunlight to enter the instrument, most of it in a narrow wavelength band around the chosen spectral line.
(Note: the 4% figure is just the pre-filtering at the entrance window, before the even sharper filtering done by the etalon.)
So the image you see is just a reconstruction of intensity using the 6 extremely narrow filters (I'm not sure precisely how they do the reconstruction; an analogous NASA instrument called HMI uses the straight average IIRC).
So, the remarks nearby about the black body emission of the Sun, etc., are correct but not relevant to the color used. The red color is just as easily viewed as the traditional coloring used for the scalar intensity represented by this image type, kind of mnemonically related to the fact that the FeI line at 617nm is in the red wavelengths.
In writing journal papers using these images, sometimes people use the longer but techically correct "pseudo-continuum intensity image" rather than the punchier "photogram". This emphasizes that the image shown is a reconstruction of the continuum intensity.
And as you say, the other "images", including magnetic field and velocity, are reconstructed using other algorithms from these 6 wavelengths. For instance, velocity is recovered because the Fe-I absorption line's location shifts with Doppler velocity along line-of-sight.
And magnetic field is recovered due to the Zeeman effect on the line shape.
It's amazing what you can do when you have so many photons!
Well, it sure does look white if you form its image on a white piece of paper, so I think it's pretty fair to call it white.
Great balls of fire!
This is great and all, but they are just snapshots in time. We need total 360 degree coverage of the sun 24/7. Stereo A and B did this great, but when Stereo B failed, it was never replaced.
Yes, full coverage is needed. And not just of the lower lattitudes from the ecliptic plane. The original Solar Orbiter proposal plan A was for a highly inclined orbit passing over the poles of the sun. But this was too expensive and instead they went with just another generic spectroscopic imager in the ecliptic plane. It was such a disappointment.
I wonder if the 4m DKIST on Earth would have higher resolution photomosaic of the sun if it were used to do this one day? Probably. It's field of view is smaller but it can image features down to the high single km scale (~8km) on the photosphere.
The problem with this is that at 10km scale the features of the sun are changing far faster than at large scales. The rows of exposures' tops and bottoms would not match very well assuming a normal raster scan. The higher the resolution the smaller the timespan you have to take the full disk image. And the higher the resolution the smaller your FOV is. It's a rough situation.
I wonder if the 4m DKIST on Earth would have higher resolution photomosaic of the sun if it were used to do this one day? Probably. It's field of view is smaller but it can image features down to the high single km scale (~8km) on the photosphere.
The problem with this is that at 10km scale the features of the sun are changing far faster than at large scales. The rows of exposures' tops and bottoms would not match very well assuming a normal raster scan. The higher the resolution the smaller the timespan you have to take the full disk image. And the higher the resolution the smaller your FOV is. It's a rough situation.
Why? How would knowledge benefit, either directly or indirectly?
I sometimes wonder if we should have probes orbiting each planet and the sun, with the most generically useful sensors, for research that isn't planned decades in advance. But I really don't know if that would be a good investment of scarce scientific resources.
I sometimes wonder if we should have probes orbiting each planet and the sun, with the most generically useful sensors, for research that isn't planned decades in advance. But I really don't know if that would be a good investment of scarce scientific resources.
Visible: https://eopro.esa.int/wp-content/uploads/2024/10/PHI_Visible...
Magnetogram: https://eopro.esa.int/wp-content/uploads/2024/10/PHI_Magneto...
Velocity map: https://eopro.esa.int/wp-content/uploads/2024/10/PHI_Velocit...
Ultraviolet: https://eopro.esa.int/wp-content/uploads/2024/10/EUI_Ultravi...