#PlanetsRotation #SolarSystem #SunandPlanets #Gravity
Have you ever wondered why planets keep rotating and revolving around the Sun? 🌍🌞 It’s a fascinating concept to think about, and there are some scientific explanations behind it. Let’s dive into the details and explore the reasons behind this incredible phenomenon.
##Understanding the Force of Gravity
First and foremost, we need to understand the force that governs the motion of planets in our solar system – gravity. Gravity is the attractive force between objects with mass, and it plays a significant role in keeping planets in orbit around the Sun. The Sun’s massive gravitational pull keeps the planets in constant motion, but it doesn’t pull them into its core. Instead, it maintains a delicate balance that allows for the planets to orbit around it.
###Balancing Act of Centripetal Force
A key concept to understand in this context is centripetal force. Centripetal force is the force that keeps an object moving in a curved path, and it is essential for understanding the motion of planets around the Sun. In the case of planets, the force of gravity from the Sun acts as the centripetal force, pulling them towards the Sun and keeping them in their orbits.
###Energy Source for Rotation
Now, let’s address the question of where planets get the energy to keep rotating. The initial motion of the planets was set in place by the gravitational interactions during the formation of the solar system. Once set in motion, the planets continue to rotate due to their own inertia, which is the tendency of objects to remain in their state of motion.
###Conservation of Angular Momentum
The conservation of angular momentum is another crucial factor in understanding why planets keep rotating. Angular momentum is a measure of the rotational motion of an object, and it is conserved unless acted upon by an external force. In the case of planets, there are no significant external forces to stop their rotational motion, allowing them to continue rotating as they orbit the Sun.
###Stability of Orbital Motion
As for the revolving motion of planets, it is indeed due to their initial momentum and the absence of significant external forces to stop them. The gravitational pull of the Sun keeps the planets in stable orbits, preventing them from collapsing into the Sun. This stable orbital motion is a result of the delicate balance between the gravitational force and the centrifugal force generated by the planets’ motion.
###Impact of Solar Wind and Radiation
It’s also worth mentioning that the solar wind and radiation from the Sun have a subtle effect on the motion of planets. While these factors do not directly drive the rotation and revolution of planets, they can influence their atmospheres and create unique phenomena such as auroras and atmospheric variations.
In conclusion, the rotation and revolution of planets around the Sun are the result of a complex interplay of gravitational forces, inertia, conservation of angular momentum, and stable orbital dynamics. These fundamental principles of physics govern the motion of celestial bodies in our solar system, creating the awe-inspiring spectacle of planetary motion.
So, the next time you gaze up at the night sky and marvel at the sight of the planets gracefully moving through space, you can appreciate the scientific wonders that bring about their mesmerizing motion. The beauty of the cosmos is a testament to the intricate laws of nature that govern the universe.
By understanding the profound science behind planetary motion, we can gain a deeper appreciation for the celestial dance that unfolds in our cosmic neighborhood. The next time someone asks, “Why do planets keep rotating and revolving around the Sun?” you’ll be equipped with the knowledge to shed light on this captivating astronomical phenomenon.
The planets don’t fall into the sun because there’s no friction in space to slow objects down. The planets are moving so fast and are far enough away, they essentially counteract the gravitational force pulling them in. I do believe that, given enough time, the planets WOULD eventually fall into the sun or be launched out because they’re too far away BUT I believe the sun will become a red giant and die long before that actually happens. We’re talking about timescales that are pretty ridiculous and the human race will probably never see any of these events occur.
A giant, spinning disk of of dust and gas coalesced to form oir solar system. In the center, the vast majority of the mass formed the sun, and the leftover bits formed the planets, their moons, and various smaller subplanetary bodies. These had their own momentum from the original disk- and as *they* themselves coalesced, they developed spin in addition to their orbits around the sun- hence rotation as well as revolution. (Think about how a figure skater starts a spin with their arms extended, then brings them in to rotate faster. This happened on the scale of the solar system and each planet.)
As for the energy to keep it all going: the planets are, continuously, falling into the sun- at least in a vector sense- but they’re moving so quickly to the side, that it balances out. You can see a similar effect by spinning a ball on a string: the ball will always be pulled down by gravity, but at the top of the loop, the string will be vertical.) Because the forces are in balance, there isn’t a need to add energy to the system. There’s no significant friction in space, so there’s nothing to slow a planet down!
Planets around the sun and moons around a planet are just at the perfect distance to keep revolving. They want to move in a straight line, but the sun’s gravity is pulling the planet closer. The planets always want to keep moving straight, and the sun is always pulling them in.
They are being pulled by the sun, they just keep missing it because they also have a velocity perpendicular to the sun. A lot of force would need to be applied to decelerate the to a speed to actually hit the sun. Sending a probe to the sun required the fastest speed we ever achieved on a man made object to de-orbit the sun.
1. Planets are being pulled in by the sun’s gravity. It’s just that they are also moving ‘forward’. Basically, they are falling in, but since they have momentum, they are stuck, never quite getting there
2. No energy is needed, there is initial momentum, but energy is needed to stop this, not keep it going.
3. Yes, it will eventually stop. This will happen when it encounters enough mass to slow it down. Fortunately, it takes a lot of dust to stop a planet moving over 100,000 km/hr. The sun will die out well before its momentum slows down.
A good analogue for an orbit is Newton’s Cannon. Imagine we stand on a mountain somewhere, the tallest one in the world. At the top we place a cannon, and fire it. The cannonball will arc through the air, propelled forward by the explosive charge of the cannon and downwards by gravity. If we make the explosive charge bigger, the cannonball will fly faster, and further. Eventually, we are giving the cannonball so much speed its going to start “missing” the earth, flying further than one might expect on a flat earth. This is because the earth is round, and so as the earth curves away, it needs to travel further before it hits the ground. Eventually, the speed is so fast it isn’t able to ever hit the ground, slamming into the back of the cannon. This is how we orbit an object, by going so fast that the distance to hit the ground never really decreases, because its falling at the same speed as the object curves away. These orbits dont last forever on earth, because we have an atmosphere, and so air will slow them down. and eventually they’ll fall out of orbit.
Thats how things orbit earth, but what about the sun and the earth? Well, in this case the earth is constantly “falling” towards the sun. But the earth is moving massively fast, 29.8 kilometers every second. Its moving so fast that its unable to fall into the sun by the same means as an orbit around earth. However with there being nothing of note in earths orbital path, its orbit can’t really decay. With nothing to slow it down, it just stays (roughly) the same speed and thus its orbit stays (roughly) the same.
The planets are essentially traveling in a straight line gravity is curving spacetime. Like one of those funnels that pennies roll around and down into except there is no friction in space to slow them down.
Look for a penny funnel game somewhere on youtube. Sometimes called a spiral wishing well or donation funnel.
In practical terms satellites and orbital items are always falling they are just moving so fast that by the time they get to that part of the fall the object they were being drawn towards is not able to meet up with them.
Think of a tennis ball tied on a rope, that you spin around your head. You pull on the rope, tugging at the tennis ball. That is gravity tugging on a planet. It doesn’t come toward you because it’s moving fast enough to go around you. If the tennis ball wasn’t moving and you pulled the rope, it would come to you.
This is a video about satellites but it explains how there’s two motions, the sideways motion and the downward motion from gravity. Enough sideways motion and the object essentially misses the planet or sun and begins orbit.
>I mean why are they not being pulled in by Sun’s gravity
They are. The reason they go around the sun is that they happen to be balanced evenly between the gravitational pull of the sun and the inertia from wherever they were going before. It’s a stable orbit.
>where are they getting the energy to keep rotating?
They already were rotating. It doesn’t take a constant input of energy like it does for us, because the planets are spinning in a (effectively) frictionless vacuum. It would take a lot of energy to stop them.
>so after sometime it should collapse right?
No but eventually yes.
When we see “orbits” collapse in models e.g. marbles in a round drain, they are being acted on by gravity AND friction, and it’s that friction which causes their “orbit” around the center to decay. With planets, there is almost no friction.
You are right to some degree though. The orbit will eventually collapse because the sun will expand and swallow the planet in about 5 billion years. Also our moon is veeeeeeery slowly slowing down our rotation. But nothing that we need to care about for a very very very very long time.
The trick to orbiting is to throw yourself at the sun and miss.
The planets are fall towards the sun, but their velocity is fast enough to keep going around. Imagine a cannon ball fired from a tower so fast it looped back around. Now image this without anti drag from an atmosphere and it can keep going forever. Constant velocity has constant energy so it’s a stable system.
So they do fall towards the sun. Gravity is pulling it towards the sun constantly.
Lets have the sun and earth positioned as shown with earth moving up.
Sun ———————— Earth ↑
In the span of 3 months the earth will fall right towards the sun by about 93 million miles.
But the earth is also moving forward really fast. In 3 months it will have traveled forward about 93 million miles.
←
earth
.
.
sun
​
So it misses the sun by quite a bit.
At that point gravity is pulling “down’ and earth is moving “left”. Again it will fall down about 93 million miles, but also travel sideways by 93 million miles….
And around and around it goes. Constantly falling but always missing the sun.
It takes as much effort to keep the planets orbiting as it does to keep you stuck on the earths surface.
The earth is trying to travel in a straight line.
The sun is trying to pull earth towards it.
The balance of those two forces is roughly a circular (it’s oblong but who cares) orbit around the sun.
If there were gas or something out there to slow the earth down that’d be a problem. But space is so empty that the minimal friction doesn’t do anything on human timescales.
They *are* being pulled in by our sun’s gravity. They’re just moving so fast sideways that they keep missing. That’s how orbit works.
They keep spinning because there’s nothing to stop them. If something is in motion, it will stay in motion until something stops it
Space is very very big and has very little resistance. Once an object gains a velocity or spin, it will have to come into contact with another object to stop it.
Gravity is a double edge sword. The sun is constantly pulling us in, as it does, we gain kinetic energy from the potential energy due to our distance from the sun. ie falling means we increase in speed.
So we fall a little bit and speed up a little bit, as we speed up, we get more energy, this causing our radius of travel to increase since the sun only pulls so much.
And there you have it, we fall, gain speed, fly out, and lose energy. Just constantly all the time.
Our moon is the only thing slowing our spin, but that is because the moon’s gravity affects the vertical circumference of the earth disproportionately, causing greater downward force and squeezing the earth and water, which causes the tides.
Orbit, in general, is what happens when you ought to fall down into whatever it is you orbiting but move too fast and keep missing it.
Since space is vacuum, better than any we managed to create here on Earth, there’s almost no energy loss to friction so it just keeps happening.
We pulled in by the Sun’s gravity, that’s why we are revolving around the sun, rotating is what most of the planets do as they revolve.
However, when the solar system was formed there was so much forward motion that the planets were moving in a direction away from the sun. Those two forces — the planets forward motion and the gravitational pull between the sun and the planets (since that’s how gravity actually works) are equal in force. So instead of the planets flinging off into space or colliding into the sun we have what we have.
Fun fact: it actually would take more energy to launch a rocket to fall into the sun, than to launch one that escapes the solar system.
In the former case, you need to completely negate the orbital velocity of the earth. In the latter, you can use the earth’s velocity as a starting boost and then add about 50% more to leave the solar system forever.
Fun and slightly related fact. It takes more energy to launch something from earth into the sun, then it takes to launch it from earth out of the solar system. Because more velocity change (delta-v) is needed for the former. The same is true for the entire earth. Continuing to orbit takes no energy due to the momentum of the moving earth.
An object’s linear momentum and angular momentum continue forever if even no further force is applied. In perfect vacuum devoid of any atoms, if you push an object out, it will continue to float out at that speed forever. Likewise, if you spin that object, it will continue to spin forever.
But in reality, planets spin slower over time, not because they are losing angular momentum, but because planets are made of different elements, so this cause frictions between those elements. That means the angular momentum is being slowly converted to thermal energy. This is why Earth spins 1 second slower for roughly every 50,000 years because the fictions bleed out the angular momentum to thermal energy or thermal radiation.
The sun is like a stay-at-arms-length parent. They’ll give you presents at Christmas but won’t tell you they love you unconditionally. So you feel like you want to be close to them but also feel like you’re spinning ever away from them. The competition between these two dynamics keeps you from developing healthy attachments but also makes it harder for you to leave them. So you’re stuck in right where you stand. Eventually your parent becomes so fat they crush you. Better that then dying from heat death. Which is when you as a millennial try to buy a home.