Could we nudge the orbit of the Earth to avoid the death of the Sun? Could it get kicked out of the solar system altogether? What are rogue exoplanets? I discuss these questions and more in today’s Ask a Spaceman!

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Episode Transcript (Auto Generated)

Our son is dying. It's true as it ages, it steadily gets brighter and hotter in less than 500 million years. The sun will become so bright and so hot that our oceans will evaporate. The continents will grind to a halt. Carbon dioxide will build up in our atmosphere and the earth will become nothing but another Venus. We are on the last chapter of the possibility of life on earth. Our only escape is to escape to move the earth as the sun gets brighter. If we move the earth into a more distant orbit, we can keep just the right temperature. But in order to raise the orbit of the earth, in order to bring it further away from the sun, we need energy. Where does that energy come from? Well, when we look for sources of orbital energy in the solar system, everybody starts looking at Jupiter.

It has the biggest mass, the biggest momentum, the biggest energy. The game here is to steal energy from Jupiter. I mean, come on, I'll barely notice in the process, it will lower its orbit and then we will give that energy to the earth, raising the orbit. Pulling us away from the increasingly deadly sun. How can this possibly work? Well, let's take away orbits for a moment. So we can think a little more linearly as in literally putting everything in a straight line. I want you to pretend that we're standing on some railroad tracks and the train is coming right at us and it's, it's far enough away. So we have enough time to talk about it and plan what we're gonna do. My goal here is to use the energy of the train to propel us forward. One simple solution to enable that is to let the train smash into us. Uh that would be messy and while parts of us may continue moving forward, that's not exactly what I meant to escape the analogy for a bit.

It would be like smashing jupiter into the earth in order to raise its orbit. But thankfully, we're not alone. We have a bouncy ball and it's a perfect bouncy ball. It cannot be destroyed, it cannot be torn apart and when it bounces it perfectly deforms and snaps back so that there's no loss of energy whatsoever. I know this is an imaginary bouncy ball, but it's the kind of bouncy ball I need for this analogy to work. And I'm going to use the bouncy ball as a go between, between me and the train and I'm gonna use it to steal energy from the train and give it to us. And so I throw the bouncy ball at the train, let's say I throw it at, I don't know, 20 miles an hour, 30 mile miles an hour, 100 miles an hour, 10 kilometers per second. It doesn't matter. I throw it with a particular speed and the train is coming at us at a particular speed. So what happens is that I throw the ball, it's headed towards the train at a particular speed and the train is headed towards the bouncy ball at a particular speed and then the bouncy ball hits the train perfectly bounces off of it.

And now the bouncy ball is going the combined speed of both the train and its original speed. But now it's headed back to us. So if I throw it at 30 miles an hour and the train is going 100 miles an hour. Now, the bouncy ball is coming back at me at 100 and 30 miles an hour and then I catch it. I don't let it bounce off me. I catch it. That is going to push me forward. I've taken the energy from the ball and it is now pushing me forward. It's just a little bit, it's just a little nudge because the ball is small and we are not. And so it's only a little bit of energy and we only get a little bit of forward momentum, but it does push me forward and then I do it again and again, And again, I keep throwing the bouncy ball at the train, letting it bounce off the train and then I catch it every time the bouncy ball hits the train, it takes a little bit of energy from the train. The train needs to expend energy to push that bouncy ball back at me. And so it goes a little bit slower and a little bit slower, but because the train is gigantic, it barely notices and then I catch the bouncy ball and it pushes me forward a little bit faster.

A little bit faster. I'm using the bouncy ball to transfer energy from the train to me. After enough times I can even match the speed of the train. Ok. With that analogy in our heads, let's orbital that. And yes, that is a new word and we're definitely going to use it. We don't have bouncy balls in space and we don't want to smack stuff into planets, which generally ends up being a bad idea, but we do have rocks, good old fashioned space rocks, asteroids, comets, meteoroids, that one wrench the astronaut dropped in the eighties, we've got stuff and instead of bouncing back and forth, we're gonna do the orbital equivalent of that. We're gonna throw a rock at Jupiter, we're gonna send it in an orbit around Jupiter so that it speeds up on its way back to earth. So Jupiter will transfer some of its orbital energy to the rock, the rock will now go faster, then it will loop back to us and will fly it around the opposite way so that it slows down and it speeds the earth up.

Now, all we need to do is repeat this a bajillion times and slowly over the course of millions of years, we will steal energy from Jupiter and we will give it to the earth. We will slowly lower the orbit of Jupiter. It will slowly get closer to the sun, but not by much because it's gigantic, but we will raise the orbit of the earth. It's just like the bouncy ball scenario with the train but in circles and with gravity instead of bounciness, what if we did something wrong though? What if this plan didn't work? I mean, if we miss you better hope that we miss on the Jupiter side of the loop. Otherwise bad news. But what if we accidentally gave ourselves too much energy? I mean, Jupiter has so much orbital energy that in my notes, I typed this sentence in all caps. We can steal energy all day long from Jupiter and Jupiter simply won't notice we can boost the orbit of the earth farther and farther and farther from the sun. What if we overdo this? What if we were to boost the earth to a velocity of 42.127 kilometers per second?

Well, if that were to happen, then the earth would escape the solar system altogether. And become a brand new kind of planet, a rogue planet. Normally I have a hard time as you know, with astronomy jargon, but this one, this one I can get behind. It's evocative, interesting, mysterious, a little sexy and it exactly describes the situation in hand. In this case, planets not attached to solar system, they're just out there doing their thing. Don't need no star wandering the interstellar depths for eternity. Lone outposts in the nameless void. These are rogue planets and we know that rogue planets exist because we've seen them, we have confirmed detections of planets that are not attached to stars, everything from earth mass to several times the mass of Jupiter. And when you get that big things start to get fuzzy, some of these very, very large rogue planets start getting names like sub brown dwarfs and there I do have a problem with the name but OK, we're just gonna, we're not gonna focus on that.

We're not gonna be negative, we're gonna be stay positive. Uh But you remember um the episode I did on brown dwarfs and there's this really fuzzy line between really super giant planets and very small star. And it's a very, very fuzzy line, this line between brown dwarf and star. There's another fuzzy line between rather large planet and brown dwarf that's on the small side, especially if they're out there on their own. And I know you're like, why is there even a definition can't, you just have planets that go into brown dwarfs that go into stars? Apparently not. I don't know why if you want me to do an episode on sub brown dwarfs just ask the question and I'll add it to the list, I promise. But anyway, rogue planets are definitely out there, there are presumably smaller ones than earth size, but we have a really hard time detecting those. And so as for numbers, total numbers of rogue planets in the galaxy, estimates paint a range anywhere from 0.25 rogue planets for every star in the milky way to 100,000 rogue planets for every star in the milky way.

That means that in our galaxy, there could be anywhere from 100 billion to 1000 trillion rogue planets. We're, we're working on firming that number up a bit, but it's hard. Look, we haven't seen a lot of rogue planets in the first place. So we're making estimates based on very, very few observations. We do not have great statistics. Our models of solar system formation and dynamics are all over the place and do not have a lot of predictive power. Some models eject jillions of rogue planets and some eject like one or two. It's just complicated and it depends on what you define to be a rogue planet. Do you go all the way down to mercury mass? Half a mercury mass? Do you count every little random piece of space? Junk as a rogue planet. Probably not. And so the numbers are all over the place we find these rogue planets almost always through a technique called microlensing where we don't get to detect the planet itself.

But occasionally, just by random coincidence, a rogue planet will pass between us and a distant star, it will cross that line of sight. And when it does the light from that star gets bent around the rogue planet, you know, typically general relativity, bending of light and it makes a little, a little blink of Starlight, not twinkle, that's an atmospheric thing, but a little blink of Starlight. And so there are dedicated surveys like the ogle telescope uh ogle which stands for, well, you know what, it doesn't really matter with a name like that. And then there's the upcoming Nancy Grace Roman telescope that's gonna find approximately a million rogue planets with the microlensing technique. We also do have infrared surveys that can find little infrared dots that are way too cold to be stars and therefore are probably rogue planets. So we have some techniques, they're not the greatest. And so we don't know of a lot of rogue planets, but we do know of some and we already saw how to do this artificially by boosting the orbit of the earth.

If we really wanted to, we could turn the earth into a rogue planet if we felt like it. But the question is, how does this happen naturally. And yes, we, we definitely see rogue planets out there in space and we definitely didn't put them there and don't say that aliens did. I, I'm watching you, there are two ways to make a rogue planet. One is that they were just born that way. Like you make stars, you make giant stars, you make medium stars, you make small stars, you make brown dwarfs, maybe you make some large i planets and that the process of star formation that starts with a giant molecular cloud that fragments and then a chunk of the gas co radically collapses and cools and condenses. Maybe this happens all the time and sometimes leads to stars. But most of the time, it simply doesn't because there's not enough stuff in this way, you make rogue planets just like you make stars. But without the nuclear fusion business, this probably explains some or many or most of, I'm not sure of the Jupiter scale rogue planets.

And we know that this is definitely a path to make rogue planets because some of the rogue planets that we've seen, especially through infrared surveys have little mini protoplanetary discs around them just like a star would, but at a much smaller scale, which is super cool because then you can imagine a rogue planet five times the mass of Jupiter orbited by a mercury size, also rogue planet and they form this little system that's just hanging out in the darkness of space. With no star. That's pretty fun to think about. I, I wouldn't want to live there, but I'd like thinking about it the other way to make road planets is going to feature your new favorite word of the day. Resonance. Resonance is this fantastic concept in physics that appears just about everywhere. And you have experienced resonance. I like to think of resonance as a day that just goes right. You ever have one of those days where you just wake up and from the first step, everything is just going your way and every positive thing that happens in the day leads to a more positive thing.

Like man, you just pick the right set of clothes. So you feel awesome. You, you sit in traffic and, and you miss most of the traffic on your way to work and because of your nice clothes, you, you get um you know, someone that you're interested in is like starts flirting with you and, and it just like compounds itself and you end up having a really epic day. You finally get that promotion you've been waiting for. It's a day where everything just clicks. Resonances are like that. But um in physics, every object, every entity in the universe has a natural motion, a natural vibration, a natural pattern. In fact, we talked about this last episode when we talked about the ph ons. These are the vibrations that uh an object can naturally support and there are these frequencies there, these vibrations that are happening everywhere. And if you approach an object and if you apply a force to it that matches that natural motion or vibration, you're going to get an automatic amplification effect.

And what you get out of it is much, much larger than what you would have suspected. And it's not like you're adding energy or, or your energy is coming out of nowhere. It's just making the maximal use of the energy that is already applied or already existing in the system like like a guitar. So you pluck a guitar string, that's not a lot of energy, just a little more, just a tiny, little bit of energy. But the entire chamber of a guitar is designed to be in resonance with those strings. So that when you pluck the string, it sets up a series of vibrations and then sound waves in the chamber and then the body of the wood itself. And these are designed to all match each other. So that little bit of energy you put in doesn't just get lost in the wind or dissipated or turned into heat. It all amplifies on itself. And all of that energy goes out into becoming a decently loud sound. That is a resonance where just a little bit of energy gets used to maximal effect.

And planets can undergo resonances too because planets are in motion. They are all orbiting something. All the planets are orbiting the sun. This is a natural rhythm, a natural orbit, a natural period. And we have an opportunity here to create resonances where a little bit of energy input can have a big effect. I need to take a quick pause here, folks to tell you that this show is sponsored by better help. And I gotta tell you adulting is really hard. It turns out that being a grown up is harder than being a quantum physicist. There are so many things that require balance. There are so many demands on your time and your attention and your energy and it's so easy to get out of balance and to get burned out. I've personally found therapy, a powerful tool for dealing with all the balancing issues in my life of how to balance a personal and professional and family and in career.

And you know, there's a lot going on and therapy has helped guide me through that to find just the right balance. And so I encourage you to give therapy a try and I'd like you to use better help. It's entirely online designed to be convenient and flexible suited to your schedule. Just fill out a brief questionnaire and you're off to the races with a licensed therapist. Find more balance with better help visit, better help dot com slash spaceman today to get 10% off your first month. That's better help he LP dot com slash spaceman. And once we're in balance, we can start tackling the whole quantum physics thing. I like to think of orbital resonances as, as little tweaks, as little whispers. A great example. Let's say we're here on the earth and uh Jupiter is over at Jupiter normal situation. Jupiter is big. Jupiter has a lot of gravity. Jupiter is also far away. So it's gravitational influence on the earth is miniscule.

It's not zero but it is very tiny. It's just a little whisper, A little. Hey, come over here. He'd come over here. Hey, come over here. That's Jupiter to us. Now, if we were up close, it'd be screaming. I was like, hey, come over here, but we're not. So we just hear a little whisper. Now, we're hearing that whisper all the time. Hey, come over here, hey, come over here. Hey, come over here. But our orbits are all over the place we have, our orbit takes a year. Jupiter has its orbit. And so we're hearing this little, hey, come over here, hey, come over here from all sorts of different directions. Like now we're hearing it from over here, but then we wait a few more months and now we're on the other end of the solar system and Jupiter is still over there and, and, and now it's coming from the opposite direction just because we're on opposite sides of the solar system. We never line up. So we're always hearing Jupiter saying, hey, come over here from different directions. So yeah, we start getting tempted, we start going a little bit over to Jupiter. But then six months later, or three years later, or a century later, Jupiter's tending tending to be over there now.

So we'd start going in the opposite direction. In the end result is everything cancels out, but it doesn't have to be. Imagine we had a resonance with Jupiter where Jupiter's influence on us matched the natural rhythm of our orbit like a guitar string in the chamber where something is in resonance where an external forcing in this case, Jupiter matches a natural frequency. Let's say we had a 2 to 1 resonance with Jupiter, which means for every one orbit of Jupiter, we do two orbits around the sun equivalently in but in the opposite way we do two orbits and Jupiter does one that is a 2 to 1 resonance and that means every two years we line up with Jupiter and then we go on our separate tracks, we go on our evolution. Then two years later, bing, we line up two years later, bing, we line up two years later, bing we line up.

So every two years, we get a little, hey, come over here and then we forget about it. Go about our lives and then two years later, you will get a text. Hey, come over here. It's a little creepy. Actually, two years later, knock on our door, hey, come over here. Super creepy. That tiny little gravitational influence that is insignificant is now in resonance. And so its effect can be amplified beyond what you might expect. It doesn't get lost in the noise, it doesn't get lost in random directions, it gets reinforced over and over and over again. That resonance if we were in a 2 to 1 residence with Jupiter, eventually after say a few 100,000 years, we would get ejected from the solar system. Why? Because every two years we get an extra little boost from Jupiter that we didn't ask for. It is very small. But every two years it happens again and again and again, every two years, we get a tiny little boost to our orbit.

Don't even need an asteroid to do it artificially, it just happens through resonance and in a phrase that is sure to date this episode and it's probably all way too late. Uh Apparently the kids are saying earth would get y out of the solar system maybe in five years. A Cathy I'll ask you to go in and delete that. So I'm not embarrassed by saying it. But that that's it. It's just earth is gone through a resonance. Guess what? These resonances happen all the time, especially in the early solar system. The early solar system did not have eight planets all in nice neat steady orbits. No, there was this protoplanetary disc, there was gas, there was dust, there are planet Testim, there are newly forming planets there are asteroids everywhere. It was chaotic. There were dozens, if not hundreds, if not thousands of potential planets in our solar system. And some of those smashed together to create the planets that we know and love today.

And some of them got stuck in resonances and once they got stuck in a resonance gone on. In fact, some models of the early solar system say that we didn't have four giant planets. We actually had five giant planets, but one of those planets got locked in a resonance with Jupiter and got scattered away from the solar system. The formation of every solar system probably generates a lot of rogue planets with the exact number depending on whatever model you want. Maybe we lost an entire gas giant 4.5 billion years ago through orbital resonances. We certainly lo lost a bunch of tiny junk random rocks and we almost certainly lost a bunch of large ish planets like mercury size earth size mars size gone through resonances. Our solar system, the nebula that formed our solar system had way more material than the modern solar system has.

And that material had to go somewhere. Some of it was just scattered away as dust and gas, some of it as tiny little micro meteoroids and some of it as rogue planets. And the resonance mechanism is one way to generate rogue planets because it's a way of very efficiently scarily, efficiently transferring orbital energy. It almost certainly happened in our past and it can happen in the future. That's right because there are resonances happening right now. For example, Neptune and Pluto are in a 3 to 2 resonance. That means for every three orbits of Neptune, we get two orbits of Pluto. There is an extra little gravitational tug happening there and trust me, Neptune doesn't care. It's way too big, but Pluto does. In fact, it's impossible for us to predict Pluto's orbit beyond 10 to 20 million years. We just can't, all of our models break down because it's too unstable because that resonance adds too much energy to the system to Pluto's orbit.

It becomes chaotic and impossible to predict. We might lose Pluto in 10 million years. Gone mercury right now doesn't have a resonance with Jupiter, but it is slowly evolving to have a resonance with Jupiter. There is something like a 5% chance that in the next billion years, we will lose mercury because once it gets locked in a resonance with Jupiter, he come over here, he come over here, he come over here gone. It happens in the moons of the outer planets, for example, three of the moons of Jupiter, Io, Europa and Ganna are locked in what's called a resonance chain. So every four orbits of IO you get two orbits of Europa and one orbit of Gimme the fourth moon of Jupiter. Calisto is slowly evolving towards joining that resonance. And once it does IO may be gone just ejected, not just from Jupiter's orbit, but from the solar system altogether.

And I is big enough, it's, it's kind of a large moon. Once it's ejected, it will be a rogue planet. Rogue planets can be created any time, usually at the beginning of a solar system formation, but always, always there's risk, especially if we start monkeying around with planetary orbits on purpose. The milky way is filled with at least billions and probably trillions of rogue planets most formed from the formation of solar systems, some formed on their own as a miniature copy of a solar system. And some in the later stages of the evolution of a solar system just through random resonances. What is life like on a rogue planet? Well, the interesting thing is is that some of them might be potentially habitable. You see the planets, especially the big ones are gonna be warm because planets are simply warm when they form because they collapse from very large gas clouds into very small volumes that generates a lot of friction. It releases a lot of heat that takes a very, very long time to dissipate.

And some of these rogue planets might have incredibly thick helium atmospheres and helium is actually rather good when it's thick enough at absorbing infrared radiation, which can trap radiation on the surface. And so when you have that you have the opportunity for Patreon, that's Patreon dot com slash P nutter it's how you can support this show. I truly, truly, I'm truly grateful for every dollar of contribution. If you do join Patreon, you get early access to episodes, you get ad free episodes except the Patreon Bay because that's baked in and you uh you get direct access to asking me questions and I appreciate it. I really do. That's Patreon dot com slash PM. Sutter. Thank you. It's fun to imagine a planet out there in the galaxy that has no star, no sun. The only source of heat is what it came with, what it was born with. It has this thick atmosphere that blocks out the sky, but traps that heat and makes the surface potentially habitable.

That is wild. If we were to turn the earth into a rogue planet, it wouldn't turn out great for us. Our core would still be warm because it's molten and still has retained heat from its formation. Some of that heat would come to the surface. So it we wouldn't be freezing cold, but it would be very cold. You could hang out and live near volcanoes and hot springs and things like that. But all the plants would die, which would generally be bad. But imagine living on a rogue planet. No sun in your sky, potentially, no star is visible. That's your entire universe sailing through the interstellar waste with the only source of amusement, the occasional star passing within a light year on second thought. Let's keep the earth right where it is. Thank you to Joseph R on email at Al mcclintock on Twitter and Keith. I on email for the questions that led to today's episode. Of course. Thank you to all my patreon contributors.

That's patreon dot com slash PM, especially my top contributors this month, Justin G Chris L Barbeque Duncan and Corey D, Justin Z, Nalla Scott M Rob H, Justin Lewis M John W Alexis Gilbert M Joshua John S Thomas D, Simon G, Aaron J, Jessica Kay and Valerie. H Thank you so much. Keep those questions coming, keep the reviews coming on itunes. That helps so much. Send me questions, ask a spaceman at gmail dot com or the website, ask apace man dot com. You can also find all the old episodes there and I will see you next time for more complete knowledge of time and space.

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