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Comment by keyle | Hacker News Reader

It's weird I wrote some sun materials in the past, for a game, and I ended up roughly with that. What I based myself on was a sci-fi movie (can't remember), and they had it right. Can't really figure out why it looks that way though, anyone care to explain why it rises and drops like that? Is there anything like currents, or it's a straight up and down? Does the sun rotate at all or it's 'static' from our perspective? (I imagine it's rotating with the stars within our galaxy)

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>a sci-fi movie (can't remember)

Sunshine, perhaps? https://en.wikipedia.org/wiki/Sunshine_(2007_film)

Brilliant, brilliant film. The premise is shonky as they come but it's obvious that the film itself has little to do with the premise. Awesome acting, literally-awesome SFX (their ability to give the sun so much weight is amazing, you really get a sense of an immortal unstoppable force), and a message that's neither shallow nor deep but prompts some self-reflection in ways you don't expect.

But at one point, they jump between two airlocks, and while in space for 10 seconds they become completely covered in ice and freeze to death.

I vaguely recall something about the making of the movie where they acknowledge that this wouldn't happen, but it was done because that's what the audience expects.

I always thought that would be a good opportunity to teach people, but I guess if you're in it to make money it makes sense to just pander to what audiences expect.

It's not about pandering or making money (did people go to the movie because they heard there was a scene where a guy freezes in space?????), it is entertainment.

It's absolutely about making money. Most movies are made primarily to make money. And the way to make money is to make it entertaining. Is it less entertaining if it's more realistic? In this particular example the answer seems to be, "yes."

My comment was from the view point of the creators (director, writer, and rest of the crew). There were better ways to make money in movies in 2007 then with a sci-fi space thriller inspired by Solaris and Alien.

To be more clear, I don't think the creators were thinking "will this scene make us more money", nor do I think it's their job. And on the topic of realism in a movie, unless it's a historical film or the goal is to educate, then realism should be near the bottom of the checklist when creating a scene.

Frustratingly, when the main character did exactly this in 2001: A Space Odyssey, the audience were frustrated because it was so unrealistic that someone would survive it (-_-)

I remember seeing the promo material for this film and thinking "nah I'll skip that one" and then I think a few years later I had a dull evening, found this film and really enjoyed it. After seeing it I recall thinking they really sold it short with the marketing, it was much better than I had expected.

Maybe I'll give it a shot. For me the premise occupies a sort of uncanny valley of realism: there's no space wizards or wormholes or FTL or aliens, but it's also not realistic enough to be something that could happen. It's kind of like that movie The Day After Tomorrow. It felt like there should have been some kind of mystical or supernatural force behind it all because it could never happen as presented, but they want it to come across as plausible.

No, it's nothing The Day After Tomorrow; the characters in sunshine aren't paper-thin stereotypes. I'd say it's a lot more like Interstellar - though all three involve "do or die" threats to the character to propel the plot, it's much more a drama working within the constraints of a proposed system, rather than a dumb big-budget thriller.

Great soundtrack too.

"[...] The gasses and plasma near the sun’s equator rotate around the sun’s axis every 25 days. As you move towards the sun’s poles, the rotation speed slows. Near the north and south poles, the sun rotates once every 36 days. That means the sun’s poles take 11 more days to rotate around the sun’s axis than its equator. The differing speeds of rotation is called differential rotation, meaning different parts rotate at different speeds. In fact, scientists divide the sun into four general sections and each section spins at a different speed.[...]"

https://nineplanets.org/questions/does-the-sun-rotate/

> Does the sun rotate at all or it's 'static' from our perspective?

It does, though not being a rigid body, the rate of rotation is a function of latitude. Near the equator, the period of rotation is ~24 days. As you near the poles, the period is closer to 30-35 days. A means of measuring these rates available to backyard astronomers is through measuring the positions of sunspots over time. [1]

[1] Please don't look at the sun through a telescope or really at all without knowing what you're doing and taking appropriate precautions: https://www.youtube.com/watch?v=R9cMXCemoJI

Not very weird, since the BBC video only illustrates resolution that's been available for the last decades.

Here's a really old picture that is at essentially the same scale as what the BBC decided to show, but made in 1997: https://en.wikipedia.org/wiki/Swedish_Vacuum_Solar_Telescope...

It's convection cells, not unlike water boiling in a kettle, the atmospheric circulation that gives us weather, or the ever-so-slow churning of solid rock in Earth's mantle that gives rise to volcanism and plate tectonics. The timescales are very different, though.

I know next to nothing about the sun but I think the article implies that it’s because of convection currents—closer to the center, plasma heats up and expands, rises, cools off, and falls back in. The picture looks vaguely like a Voronoi diagram too, which sort of fits as the plasma has to spread out of its own hot plume before sinking.

I had a similar comment about voronoi. Nature and science are beautiful.

Close. The Sun is not a fully convective star. Convection only occurs in the outer 30% or so. The inner part is called the radiation zone [1] and it is here that energy from fusion in the core makes its way out by radiative transfer as well as conduction. This is a very slow process compared to convection, taking more than 170,000 years for the photos produced by fusion to reach the convection zone.

[1] https://en.wikipedia.org/wiki/Radiation_zone

Wouldn’t we be observing the outer 30% (or 1%) though? From the diagram on the page you linked it seems that the granules in the photo exist in the photosphere, where convection is the dominant mode of energy transfer. That said, none of the conduction could happen without radiation further inside.

Yeah, we’re seeing the convection from the outer 30%, bubbling up on the surface of the photosphere. All of the fusion takes place down in the core though. It’s very difficult to fuse hydrogen and so it can only occur at the extreme pressures in the middle of the sun.

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