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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

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.

eleveriven 2y ago
When you think about it - 43 million kilometers away, and still nearly 20kW per square meter - that’s an immense amount of power
onemoresoop 2y ago
And that is in all directions!
deleted 2y ago
[deleted]
KineticLensman 2y ago
> 43 million km away er, 149 million km away [0] not 43 [0] https://en.wikipedia.org/wiki/Sun https://en.wikipedia.org/wiki/Sun
- grues-dinner 2y ago
  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).
  - KineticLensman 2y ago
    Oops, my bad
  - PittleyDunkin 2y ago
    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.
    - KineticLensman 2y ago
      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_Orbiter/New_full_Sun_views_show_sunspots_fields_and_restless_plasma https://www.esa.int/Science_Exploration/Space_Science/Solar_...
      - lovecg 2y ago
        Well, they’re _technically_ correct.
      - grues-dinner 2y ago
        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-mission#solar-orbiter-mission https://www.eoportal.org/satellite-missions/solar-orbiter-mi...
- dredmorbius 2y ago
  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.)
popol12 2y ago
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 ?
- grues-dinner 2y ago
  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.
- burnt-resistor 2y ago
  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.
  - popol12 2y ago
    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 :)
    - burnt-resistor 2y ago
jmyeet 2y ago
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.
- grues-dinner 2y ago
  You just reminded me of https://spacesounds.com 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!
- stouset 2y ago
  One of the detections was of a merger that momentarily had a higher power output than the entire rest of the visible universe combined.
- crazygringo 2y ago
  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/ 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 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?
dylan604 2y ago
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.
- delta_p_delta_x 2y ago
  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.
itishappy 2y ago
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.
- joering2 2y ago
  otherwise we obviously wouldn't have been here.
brcmthrowaway 2y ago
The Sun is eldritch horror. The test of being human is being fine with it.

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.

eleveriven 2y ago

When you think about it - 43 million kilometers away, and still nearly 20kW per square meter - that’s an immense amount of power

onemoresoop 2y ago

And that is in all directions!

deleted 2y ago

[deleted]

KineticLensman 2y ago

> 43 million km away er, 149 million km away [0] not 43 [0] https://en.wikipedia.org/wiki/Sun https://en.wikipedia.org/wiki/Sun

grues-dinner 2y ago
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).
- KineticLensman 2y ago
  Oops, my bad
- PittleyDunkin 2y ago
  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.
  - KineticLensman 2y ago
    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_Orbiter/New_full_Sun_views_show_sunspots_fields_and_restless_plasma https://www.esa.int/Science_Exploration/Space_Science/Solar_...
    - lovecg 2y ago
      Well, they’re _technically_ correct.
    - grues-dinner 2y ago
      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-mission#solar-orbiter-mission https://www.eoportal.org/satellite-missions/solar-orbiter-mi...
dredmorbius 2y ago
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.)

popol12 2y ago

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 ?

grues-dinner 2y ago
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.
burnt-resistor 2y ago
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.
- popol12 2y ago
  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 :)
  - burnt-resistor 2y ago

jmyeet 2y ago

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.

grues-dinner 2y ago
You just reminded me of https://spacesounds.com 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!
stouset 2y ago
One of the detections was of a merger that momentarily had a higher power output than the entire rest of the visible universe combined.
crazygringo 2y ago
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/ 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 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?

dylan604 2y ago

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.

delta_p_delta_x 2y ago
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.

itishappy 2y ago

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.

joering2 2y ago
otherwise we obviously wouldn't have been here.

brcmthrowaway 2y ago

The Sun is eldritch horror. The test of being human is being fine with it.