What's Directly Above and Below the Sun? - Nuclear Engineer Reacts to Insane Curiosity

Ajouté : 2026-05-27

[00:00:00]The new prediction looks closer to a deflated croissant, a curved central bulge with Today we're going to be answering the question, why can't we go up? Cuz after all, the solar system is more than two-dimensional. This video is by Insane Curiosity. Let's find out.

[00:00:17]Spacecraft have reached every planet in the solar system. Let's let that sink in for a bit, because people hear this pretty often. This is a pretty well-known fact, but the engineering is quite extraordinary. Cuz that means we built machines that survived Venusian pressure, Jovian radiation, Martian dust storms, Saturnian cryogenic temperatures, and even interstellar space. So, these probes are autonomous, nuclear-grade in some cases, powered by radioactive decay, industrial systems thrown into environments where repair is impossible, and communication delays can be several hours. And that's why those probes' design philosophy is close to a reactor safety system in terms of redundancy, fault tolerance, and radiation hardening. Rovers are driving across Mars right now. Mhm.

[00:01:14]>> A probe was dropped through the clouds of Saturn, and Pluto was photographed from less than 8,000 mi away.

[00:01:20]Crossing billions of miles of >> that he brings up Pluto, even though it's considered a dwarf planet now, but I remember learning about Pluto as a planet when I was in elementary school. Empty space has started to feel almost routine.

[00:01:34]Yes, normalizing interplanetary travel, and yet we sometimes struggle to know how to fix printers. Though, I actually think printers are harder than space.

[00:01:44]Let me know if you disagree.

[00:01:46]But there is one direction we've barely touched, one place that should be the easiest to reach, and turns out to be one of the hardest.

[00:01:53]Straight up. Out of the flat plane the planets all share, directly above or below the sun.

[00:02:00]This is counterintuitive and I'm sure a question that just about everybody asked when they first learned about the planets in elementary school. And well, we are already moving sideways around the sun at absurd speeds whether we want to or not. The vertical exit from our solar system.

[00:02:19]It sounds simple. Just point the rocket up and go. The problem is that physics will not let you.

[00:02:26]What follows is why it's Going to need more rocket than that.

[00:02:29]>> caping vertically is harder than going to Pluto.

[00:02:31]You will see what waits up there if a spacecraft ever makes the trip. And you will see the strange maneuver scientists are now considering.

[00:02:40]A maneuver where a probe has to first fall toward the sun before it can ever climb away from it. And that's harder than a lot of people think. People talk about sending things to the sun. There is even some out there recommendations of {quote} and {unquote} solving the nuclear waste problem by launching it into space and not just doing that but sending it to the sun cuz that's easier.

[00:03:04]Apparently. Well, I guess if you apparently think sending nuclear waste into space is easier than constructing dry cask storage, well I think that one just sounds more scientifically sexy because dry cask storage is boring and routine.

[00:03:23]To understand why vertical escape is hard, you have to understand what speed you already have without >> Yes.

[00:03:29]>> doing anything.

[00:03:31]The Earth is moving right now around the sun at roughly 30 km per second or about 67,000 mph. Yep. Everything, you, the oceans, the atmosphere, the stationary nuclear power plants that are orbiting a much larger nuclear power plant. Well, it uses fusion but without it we'd be in dire straits. But the point is that velocity is relative, so you don't feel it. This is kind of like neutron moderation in a reactor. Inside the neutron population's frame of reference, things seem stable, but energetically the particles are screaming around at extraordinary velocities.

[00:04:08]That is not a typo.

[00:04:10]Every second the planet you are standing on travels 30 km sideways around the sun.

[00:04:14]>> Yep.

[00:04:15]Every rocket we launch from Earth inherits that motion. Yes. You don't start from zero, you inherit the state of the system. Kind of like inherited neutron spectra within a reactor core.

[00:04:27]After all, a rocket launched from Earth is already part of a gigantic solar orbital machine. When SpaceX or NASA puts a probe in space, the probe is not starting from rest. It is already moving sideways at 30 km per second, the same as the rest of us.

[00:04:45]This is normally a gift. If we want to reach Mars, the existing sideways motion does most of the work. Yes.

[00:04:52]Energetically, Mars is another lane on the same racetrack. So, traveling huge distances within the same plane is relatively efficient, but orbital plane changes horrifyingly expensive. It's why you hear NASA talk a lot more about delta V than they do about distance. It's a big misconception out there that it's about distance. Kind of like in nuclear engineering, temperature is not always your limiting factor. Transfer of enthalpy, the rate of transfer of enthalpy often is. That is to say, internal energy. We just have to adjust slightly.

[00:05:28]A few kilometers per second of extra velocity in the right direction. A few kilometers per second, that's slight in planetary terms.

[00:05:35]>> And we are on a trajectory to another planet.

[00:05:39]Well, what happens when you want to go up? Not towards Mars, Jupiter, or anywhere else in the plane. Straight up, perpendicular to everything else.

[00:05:48]>> Yeah.

[00:05:50]Now, that sideways motion becomes your enemy.

[00:05:53]Go straight up, you first have to cancel out the 30 km/s you already have. Yes, that enormous sideways kinetic energy.

[00:06:01]About the same as trying to stop a turbine rotor on the main turbine at a nuclear power plant that's already spinning at thousands of RPM instantly.

[00:06:11]And kinetic energy scales with velocity squared. The Newtonian kinetic energy formula is 1/2 mv^2. Same reason why reactor pressure vessel failures are terrifying. Turbine overspeed can be catastrophic to the turbine, and plasma confinement infusion becomes really, really hard.

[00:06:33]It's really hard when things scale with something squared like that. Then you have to add new velocity to climb. The total energy required is staggering.

[00:06:43]Mission planners measure this in something called delta V. It's the change in velocity a spacecraft has to produce on its own.

[00:06:51]Going to Mars from Earth orbit needs about 4 km/s of delta V. And that's relatively small. He said small earlier because you're reshaping an existing solar orbit rather than fighting the sun directly. Going straight up out of the ecliptic plane needs roughly 30 km/s, almost 10 times as much. Yep, and again, 10 times as much velocity figures out to about 100 times more energy. You might as well be trying to redirect reactor coolant flow without turning the pumps off first. And those pumps individually, over 100,000 gallons per minute at well over 2200 PSI. So, a lot of energy and a lot of inertia.

[00:07:36]That is the prison. Earth's orbital motion gives us free speed in one direction, and effectively walls us in.

[00:07:43]We can't go around the Sun easily. We can hop to other planets in the same plane easily, but the moment we try to leave the plane itself, we have to fight 4.6 billion years of orbital momentum all at once.

[00:07:57]Good bit of momentum and inertia.

[00:07:59]>> one of the most counterintuitive facts in astrodynamics.

[00:08:03]Reaching Pluto, 3 and 1/2 miles away requires less energy than reaching a point just a few million miles directly above the Sun's North Pole. Well, when you're dealing with a hundred times more energy per unit, then yeah. Orbital mechanics cares a lot more about vector direction than distance.

[00:08:20]Because the vertical exit is so expensive, almost no spacecraft has ever made the trip, which means almost everything that happens directly above or below the Sun is still, in 2026, a frontier.

[00:08:33]We have detailed maps of Mars and high-resolution photographs of Pluto. We can show you close-up imagery of comets, asteroids, the rings of Saturn, and the moons of Jupiter, but the poles of our own Sun, the closest star to Earth, have barely been seen. This It's funny cuz this sounds counterintuitive cuz it sounds like you have detailed neutron flux maps of the parking lot, but not the top of the reactor containment building. Obviously, that's not the case.

[00:09:03]There is a reason this matters more than it sounds. The polar regions of the Sun are where the most violent and most important solar activity actually happens.

[00:09:11]>> Yeah. The fastest solar winds come from there. The magnetic field of the Sun reverses itself every 11 years, the Yeah. So, the Sun is basically a giant MHD, that's magnetohydrodynamic fusion reactor. That is to say, its magnetic field is not a static stable system. And 11 years is super fast for something that operates on the order of billions of years, but it twists, reconnects, stop, reorganizes. They have a lot of magnetic instability, which is something you run into when you're trying to do fusion on Earth as well. And this is a stable one, a really big stable one. The process is that begin at the poles.

[00:09:49]The entire space weather environment of our solar system is shaped by what happens above and below the equator of our star. And we have been observing it almost entirely from the side.

[00:10:01]Yes, and that's not great when it comes to monitoring any reactor. So in nuclear power plants, we look at what's known as axial flux distribution. That is to say, where the power in the reactor is being produced relative to the top or the bottom of the core, as well as radial flux. That is to say, in the sides versus the center. This would be like trying to predict full-on neutron flux behavior while just looking at one of those things. That's not great cuz you missed a lot of critical geometry. Like trying to understand the weather of an entire planet by only ever standing at the equator. Mhm. There've only been two missions that ever managed a real polar view of the sun. The first was Ulysses launched in 1990 by a joint NASA and ESA partnership.

[00:10:46]To get out of the ecliptic plane, Ulysses had to take a wild detour. Mhm.

[00:10:50]The spacecraft first traveled outward to Jupiter, then used the gas giant's gravity as a slingshot to bend its trajectory nearly 80° out of the planetary plane.

[00:11:01]Yes, gravity assists or orbital momentum theft. Borrowing tiny amounts of kinetic energy from a planet. Don't need much cuz you're talking about the difference between a tiny probe and a planet. But just like in neutron multiplication, where small interactions produce large macroscopic outcomes, quite remarkable.

[00:11:20]From there, it fell back inward toward the sun on a tilted orbit. Mhm. The mission worked. Ulysses gave us our first direct And that's really impressive cuz there's a lot of things that can go wrong with spacecraft. I mean, for one, radiation around Jupiter is not trivial, but you also have software problems, thermal cycling, communication problems that can just mess with you. So, that's pretty impressive. measurements of the fast solar wind streaming for the polar coronal holes, but the spacecraft was built with 1980s instruments.

[00:11:49]>> Mhm. It had no cameras capable of imaging the poles.

[00:11:53]We learned about the conditions there, but never actually saw them.

[00:11:56]The second mission is happening right now. Solar Orbiter, a European Space Agency probe launched in 2020, has been gradually tilting its orbit using gravity assist from Venus.

[00:12:07]Yep.

[00:12:07]>> In March 2025, Solar Orbiter sent back Gravity assists are the only roughly economical ways to do it. Otherwise, you spend a stupid amount of money on rockets. back the first direct images of the Sun's South Pole ever taken in human history.

[00:12:22]The pictures show a chaotic, magnetically tangled region, Mhm.

[00:12:26]nothing like the smoother solar surface we see from Earth. Yeah. Think about that. Until last year, >> Chaos zones, hotspots, if you will.

[00:12:35]>> no human or robot has ever seen what the top or bottom of our Sun looks like.

[00:12:40]Mhm. Not really. Not from above.

[00:12:42]The closest and brightest object in our >> How do you know which one's the top and which one's the bottom?

[00:12:48]local universe and arguably the most important still has two regions we have only just begun to photograph.

[00:12:55]There is a second reason vertical escape matters. We do not actually know what our own solar system looks like from outside.

[00:13:02]Around the Sun, there is a vast bubble called the heliosphere.

[00:13:06]It is the So, this is interesting cuz it's sort of the Sun's containment field. After all, the solar wind carries plasma outward, dragging magnetic magnetic fields along with it, and it shields against portions of cosmic radiation. Though, it's not a solid barrier. It's a dynamic plasma interaction zone. Sort of like magnetized reactor coolant flow extending billions of kilometers. Region of space where the solar wind dominates, pushing back against the interstellar medium beyond it.

[00:13:38]Inside this bubble live the planets and the comets and every human spacecraft we have ever launched.

[00:13:44]Outside the deep galactic environment >> Showing it looking like a comet.

[00:13:49]>> and interstellar particles that our bubble shields us from. Hm. For decades we assumed the heliosphere was shaped like a comet. A rounded front where it pushes against the interstellar wind in the direction of our galactic motion and a long tail trailing behind. This was the standard textbook image.

[00:14:06]It was a Interesting.

[00:14:08]>> good guess given the data we had.

[00:14:09]>> Sure. In 2020 a team led by Merav Opher at Boston University, using a new model based on NASA data, came to a different conclusion. The heliosphere is probably not comet-shaped at all. Hm. I mean, after all, models improve when instrumentation improves. Just like the very logo that exists for atomic energy, where it shows an atom as a nucleus with electrons orbiting it, kind of like a solar system. Doesn't do that. They don't follow predictable patterns. It's all probability distribution functions known as electron clouds.

[00:14:48]But, for quite a while, that was the model. And new models come out all the time. The new prediction looks closer to a deflated croissant, a curved central bulge with Love the pronunciation. two short jets curling away from it and notably no long tail.

[00:15:07]The reason we cannot tell for certain >> Certainly more appetizing this time.

[00:15:10]>> is that we have never seen our bubble from outside and we've never sent a probe high above the ecliptic plane far enough to take its measurements from a useful angle.

[00:15:19]The The spacecraft crossed the heliopause sideways, almost in the plane of the planets. Useful, but not limited.

[00:15:27]To actually understand the shape of our home in the galaxy, we would need a probe traveling well out of the ecliptic, looking down at the structure from above.

[00:15:35]I guess it's looked down on everyone.

[00:15:36]There is a NASA mission called IMAP, the Interstellar Mapping and Acceleration Probe, designed to refine our understanding from the inside.

[00:15:44]But for a direct view of the bubble's true shape, the only way is to escape vertically and look back at it. Mhm. A vantage no spacecraft has ever reached for a structure we live inside without knowing its real form.

[00:15:56]How do you actually solve the vertical escape problem? You cannot just build a bigger rocket. The energy required to cancel our orbital motion is too large for any reasonable of fuel load. Yeah, yeah. You're you'd be talking about like science fiction rocket fuel or and it's even more than the fuel, it would be the durability of making something that can withstand the force produced from said fuel.

[00:16:21]There is a counterintuitive solution that has been discussed in mission design circles for years, and it is starting to move from theory toward concrete proposals.

[00:16:30]It is called the Solar Oberth maneuver.

[00:16:33]Mhm. The idea works backwards from how rockets normally fly.

[00:16:37]Instead of pointing your engines upward and trying to climb, you do the opposite. You drop your spacecraft toward the sun. You let it fall inward, accelerating under solar gravity until at its closest approach, it is moving at hundreds of kilometers per second, possibly more than 100 kilometers per second at perihelion.

[00:16:54]Wow, it's a lot of kinetic energy.

[00:16:56]Though, the deeper you fall, the more kinetic energy gain. Then, at exactly that moment, you fire your engines.

[00:17:03]>> Mhm.

[00:17:04]Why? Because of a principle Hermann Oberth wrote down in 1929.

[00:17:09]A rocket burn is dramatically more efficient when performed at high velocity in a deep gravitational well.

[00:17:15]The same amount of fuel gives you a much larger increase in orbital energy at perihelion than it would in empty space.

[00:17:22]By burning at the closest possible approach to the Sun, you get a slingshot effect without the slingshot.

[00:17:28]Okay, and that's again, it's scaling quadratically. That is to say the kinetic energy scales with velocity squared. Sort of like inserting reactivity at peak neutron flux. Going to give you way more of a surge, or in the case of negative reactivity, so you're inserting control rod, it's going to give you way more of a sag. The fuel you carried up from Earth turns into far more kinetic energy than it would have anywhere else.

[00:17:55]After the burn, your spacecraft is moving so fast, in such a useful direction, that you can finally climb out of the plane and head straight up toward the solar poles, or directly out of the solar system. The dive becomes the launch pad. Well said. Sometimes the fastest way outward is inward first. You see this with inertial confinement fusion. You have to compress inward violently before the expansion releases energy outward. Solar sails are also part of the conversation. Mission concepts, like the proposed solar polar imager and the more recent high inclination solar mission, rely on enormous reflective sheets that use the pressure of sunlight itself to slowly tilt the spacecraft's orbit.

[00:18:38]Just photons. Just photons pushing on a thin metallic film. Photons do carry momentum. That's actually one thing you calculate relatively early on in nuclear engineering classes is calculating the momentum of photons. Individually, it's going to be tiny. I mean, after all, you're going to measure them in electron volts to millions of electron volts, really small unit of energy. But, this is a huge integrated effect over several years, or continuous acceleration, but very, very low thrust. Kind of like ion propulsion's even more patient cousin, Or, using energy from reactor decay heat rather than doing fission itself. In the case of RTGs, which incidentally do run space probes. Thousands of square meters across, sails can take years to spiral up to a polar orbit. But, they need no propellant. And the longer they push, the higher the inclination they can reach.

[00:19:34]Obviously, just showing an artist representation of photons hitting a surface. You're not getting any gigantic chunky photons. Mind the two, a spacecraft that uses a solar sail to spiral closer and closer to the sun, then performs an Oberth maneuver at perihelion to direct itself vertically.

[00:19:53]Then Same thing, just using a different engine. continues riding the sail out into the polar regions.

[00:20:00]This is the kind of mission architecture that astrodynamicists now think could finally give us a clean view of what lies directly above and below our star.

[00:20:10]If we ever pull this off, what does a spacecraft actually see from directly above the sun?

[00:20:17]First, the view changes physically. The ecliptic plane is dirty. Earth, like every planet, swims through a thin haze of dust left over from billions of years of comets, asteroid collisions, and the slow grinding of the solar system. So, a lot of people think space is empty, which it kind of is, but it's not perfectly empty. It's just extraordinarily diffused. You can actually see this dust with your own eyes.

[00:20:40]On a very dark night, just after sunset or before If you're away from cities, yes.

[00:20:44]>> sunrise, a faint pyramid of light called the zodiacal light reaches up from the horizon.

[00:20:50]That glow is sunlight reflecting off the dust in our local plane. It is the inside of our solar system lit up.

[00:20:56]A spacecraft that climbs above the ecliptic would rise out of this dust within months.

[00:21:01]Now, that's really cool. This is akin to an observer just getting out of the fog, and you can see a lot further. It'd be a lot easier to spot exoplanets this way, just by getting out of the dust within the solar plane. Similar to radiation shielding specifically for reactor instrumentation, you don't just need shielding to protect personnel from high radiation, you need it to protect sensitive instruments. Because reducing all that background noise lets you detect weak but important signals. The view there is dramatically cleaner, less scattered light, less background haze.

[00:21:37]The kind of place where a telescope could detect faint signals that from inside the disc are drowned out by the dust around us.

[00:21:44]It would be one of the best possible vantage points for an instrument looking for signs of life around other stars.

[00:21:50]Mhm. From the same vantage, a different instrument could measure the cosmic microwave background or study the structure of the galactic plane from outside it.

[00:22:00]Second, the solar environment changes.

[00:22:02]Above the equator of the sun, the slow solar wind around 400 km per second of turbulent plasma gives way to something steadier.

[00:22:10]I was showing the Earth-Sun Lagrange points. Above the polar coronal holes, there is a stream of fast solar wind between 700 and 800 km per second of particles flowing outward in a thinner, smoother current. So, the sun kind of has these weather regimes, which is interesting. And that's where plasma physics is the dominating field, if you will. I mean, plasma is one of the weirder counterintuitive states of matter, cuz it's electrically conductive, magnetically structured, but inherently unstable. And fusion researchers fight this all the time.

[00:22:45]It's part of their job. The sun cheats by brute forcing it with its gravity.

[00:22:50]And that's how it's sustained fusion for billions of years.

[00:22:53]A spacecraft riding through this stream would experience a fundamentally different radiation environment, with implications for both the lifespan of its electronics and the science it could perform. Mhm. And third, the bigger picture. From advantage well above the ecliptic, the solar system itself would be visible as the disk it actually is.

[00:23:13]You would see the planets in their flat ring around the Sun with the dust hugging the plane and the heliosphere wrapped around all of it in whatever real shape it happens to have.

[00:23:23]We would be able to look You could see if it's a croissant or a comet or a croissant. down at our own neighborhood for the first time, the same way we look down at Earth from orbit.

[00:23:34]We've never seen this view. Not a single human or robot has ever sent back the photograph.

[00:23:40]Of all the images we have managed to take of the cosmos, the one looking down at our own solar system from outside its plane is still missing.

[00:23:49]And And then you're going to need to take one outside of our galaxy looking down at its plane.

[00:23:54]you. If you had to design the first mission to climb to directly above the Sun, would you bet on a solar sail, the slow patient way, or an Oberth dive, the violent and dramatic way? All right. So, as a nuclear engineer wanting to hedge my bets, use both. Solar sail for gradual orbital shaping and Oberth dive for the massive final energy kick. But, if you're going to make me pick, Oberth dive all the way. The solar sail is elegant, efficient, and patient, but I'd prefer the Oberth maneuver because it's pure ruthless physics exploitation. And that's what you need for this project.

[00:24:34]And again, it's what helps you get over that 30 km a second. And again, this would be like inserting reactivity at the point of maximum neutron importance or neutron worth. And that is actually something you calculate in nuclear power plants is how much of the rods going to do, how much of the effect it's going to have on a reactor power over core life.

[00:24:56]And here, timing and location would matter just as much as raw power in both cases really. And again, the trade-off is the solar sail is strategic patience and the Oberth dive is the exploitation of existing energy fields.

[00:25:12]And the way I see it is don't try to carry all the energy yourself if physics already provides the giant energy source. Now, the downside is near sun operations are quite extreme and deep perihelion the spacecraft is basically a heat shield with a mission attached.

[00:25:29]You're be dealing with insane radiation, plasma, and a whole lot of heat flux.

[00:25:35]So, the real answer is probably some hybrid or do both and see which one works better cuz it's not like you're just going to do this once and be done with it. I'd go with the Oberth dive if I had to just pick one for the purpose of this question. Let me know if you'd pick differently. Thanks so much for the recommendation and thanks so much for watching. I'll see you next time.