# If the Sun disappears right now, when the absence of its gravity affects on Earth?

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Imagine if the Sun disappears right now. When the Earth will be affected by its absence? Does it affect immediately, or it takes almost 8 minutes? (The time that light travels from the Sun to the Earth.)

So if I ask this question in another way, the changes in Space-Time will affect immediately or it will travel by light speed?

As we know by General Relativity, gravity propagates by the speed of light c = 299,792,458 m/s in a vacuuum (like space).

The average distance between the earth and sun is about 149.6 million kilometers, so it takes light about 8.3 minutes from the sun to earth.

This means, if the sun were to disappear right now, we would have to wait 8 minutes and 20 seconds until we would realize. Luckily, by all known laws of physics, this is not possible :)

I found my answer here :

it seems my question was already has been answered by Albert Einstein.it's called cosmic catastrophe. according to that page In Einstein's spacetime model, the disappearance of the sun would create gravitational waves in the spacetime. The gravitational waves travel at the speed of light, and an orbiting planet would not react to the sun's disappearance until after the gravitational wave has reached it. Only then, the planet would start to travel in a straight line.

In a very real and fundamental way "This can't happen" Not only practically (you can't make the sun disappear) But in a fundamental way, you can't make mass disappear.

Even if you suddenly converted all the mass of the sun into energy, that energy would still have a gravitational effect. And removing the mass of the sun, at speeds greater than the speed of light fundamentally breaks the very physical laws which you need to base any answer on.

So this is a frame challenge answer. It is theoretically impossible to make mass disappear.

## What would happen if the sun disappeared right now?

INSPIRED BY THIS intriguing YouTube video, we’re going to dive into the tantalising question:

What would happen if the sun disappeared this very second?

The sun is about 333,000 times the mass of Earth and produces the same amount of energy as 100 billion hydrogen bombs every second.

Its giant mass makes the sun the dominant gravitational force in the solar system that locks all eight planets into elliptical orbits.

At the same time, the sun’s enormous energy heats our planet just enough so that Earth’s surface is the right temperature for liquid water — the catalyst for life.

But what would happen if we lost the sun?

What might seem like a silly question on the surface was actually an important thought experiment for Albert Einstein.

### The speed of gravity

Before Einstein attacked this problem, scientists suspected — but hadn’t proved — that gravity acted instantaneously.

If that were true, then the first thing that would happen when the sun disappeared is that Earth, along with all the other planets, would go flying off into space. It would be complete and utter chaos in our solar system.

Source: pep151astronomy via Flickr/Creative Commons

Light, on the other hand, is not instantaneous: It travels at approximately 1080 million kilometers per hour and takes roughly 8 minutes to reach Earth. Therefore, we would still see the sun in our sky eight minutes after it was gone.

So, if the speed of light is a constant and the speed of gravity is instantaneous, then we would feel the sun’s disappearance before we saw it.

But, as Einstein showed in in his theory of general relativity that he introduced in 1915, the force from gravity is not instantaneous. In fact, it travels the same speed as light.

Therefore, if the sun disappeared, we would remain blissfully unaware for eight minutes that inevitable doom was upon us.

### Eternal night

We wouldn’t be left in complete and utter darkness, however.

The stars would still shine, and electricity would continue to work so cities would remain lit for as long as the power lasted. Even the planets would remain visible for a brief time.

For example, when Jupiter is closest to Earth it’s about 33 light minutes away, which means we would continue to see the giant planet for over an hour — the time it would take for residual sunlight to reach Jupiter and reflect back to Earth — after the sun was gone.

Source: Scott Cresswell via Flickr/Creative Commons

But after eight minutes, one thing on Earth would come to a screeching halt, explains Michael Stevens, who founded and stars in the widely popular YouTube channel Vsauce.

Without sunlight, photosynthesis — the process by which all plants generate food — would stop the second the sunlight winked out in our sky.

Most small plants would die within a matter of days, but that’s not what we should be worried about: Earth’s average surface temperature would drop to 0 degrees Celsius after the first week, and then to minus 100 degrees by the end of the first year, Stevens says.

All the while, Earth’s oceans would grow ever colder, eventually freezing over, transforming Earth into an ice world.

But just like deep lakes in winter, only the surface would freeze, leaving a liquid ocean underneath. If any humans survived this extreme transformation, their only refuge, according to Stevens, would be near geothermal vents on the ocean floor.

These vents emit heat that wells up from the center of the Earth.

### Life on Earth would thrive for billions of years

Thousands of shrimp thrive around hydrothermal vents on the ocean floor.

This way of life would be miserably dark and lonely, and it is difficult to know whether humans would last long under these conditions.

On the other hand, the animals that live around these vents today would continue surviving for billions of years after the sun vanished. That’s because these animals don’t need the sun to live.

Shrimp and crabs living near the summit of Northwest Rota-1 volcano graze bacterial mats on the rocks at hydrothermal vents. Source: NOAA Photo Library via Flickr/Creative Commons

Instead, they get their food and energy from the heat coming out of these geothermal vents.

While most life would be extinguished from our planet without the sun, these geothermal-loving organisms would continue to thrive for billions of years without a single care that the sun no longer existed.

Oddly enough, this ice ball Earth resembles some of the moons around Jupiter that astrobiologist suspect could harbor extraterrestrial microbes.

### What lies beyond

This artist’s impression shows the planet orbiting the star Alpha Centauri B, a member of the triple star system that is the closest to Earth. Alpha Centauri B is the most brilliant object in the sky and the other dazzling object is Alpha Centauri A. Our own Sun is visible to the upper right.

Right now, Earth is orbiting the sun at a blazing speed of 107,000 kilometers per hour. If the sun vanished, its gravitational pull would be gone, but Earth’s speed would remain the same.

To understand why, picture yourself tying a rock to the end of a string and then swinging that string in a circle over your head. Then you let go of the string. The rock goes flying in a straight line away from you, the same way that Earth would go flying in a straight line away from the central point in space where the sun used to sit.

This artist’s impression shows the planet orbiting the star Alpha Centauri B, a member of the triple star system that is the closest to Earth. Alpha Centauri B is the most brilliant object in the sky and the other dazzling object is Alpha Centauri A. Our own Sun is visible to the upper right. Source: ESO/L. Calçada

As long as Earth didn’t collide with any other planets, asteroids, or comets, it would only take about 377,000 hours (43,000 years) for it to traverse 4.3 light years — the distance to the nearest star, Alpha Centauri.

And after 1 billion years, Steven calculates, Earth would have traveled 100,000 light years, or the length of the entire Milky Way Galaxy.

Who’s to say our tiny planet wouldn’t get picked up and pulled into orbit by another star or, perhaps, a black hole? The Milky Way harbors an estimated 100 billion stars and as many as a billion black holes. Whatever the outcome, Earth’s future after no sun would be an exciting adventure across the cosmos.

Check out the two YouTube videos that inspired this post below:

First, let’s be clear on one point. The Sun can’t be “put out” like fire on Earth, and it’s unlikely that such a massive ball of burning gas could suddenly dissipate. Still it’s an interesting thought experiment — what would happen if it vanished?

The Sun produces the same amount of energy per second as 100 million hydrogen bombs, and it’s responsible for life on Earth. It’s also the gravitational lynchpin of the solar system, without which none of the planets would have even formed. So if the Sun were to implode or otherwise wink out of existence like a dead lightbulb, what would actually happen here on Earth?

Because of our distance from the Sun, we wouldn’t even know that the sun had disappeared for approximately 8 and a half minutes. We would still see its ghost floating in the sky until its last rays of light reached us through space. At that point, eternal night would fall, pierced only by starlight — even the moon would fade away, since it doesn’t produce any light of its own.

As those last sunbeams die away, so will the main processes driving life on Earth. Without sunlight, plants can no longer convert energy into food through photosynthesis. They wouldn’t die immediately, and some trees could probably last a few decades given their slow metabolism and considerable storage space. But as the eternal night stretched on and on, the entire base of the food chain would eventually die off followed by herbivores, carnivores, and the rest.

But even before we ran out of food, the Earth’s surface would cool beneath livable temperatures. Within the first week, average global surface temperatures would drop below -20 degrees Celsius, and by the end of the year down to -100 degrees Celsius. The oceans would completely freeze over except surface layer of ice which would actually insulate the waters beneath. Shielded from the colder air, the waters could remain liquid for hundreds of thousands of years.

While life on the rest of the planet would soon extinguish, those oceans could still harbor life. Life on Earth has certainly enjoyed a boost from the Sun’s energy, but our planet has its own store of heat leftover from its formation. This heat radiates from the core out of hydrothermal vents on the ocean floor, where complex ecosystems have thrived for billions of years. Even without a local star, these lifeforms would happily survive on geothermal energy for billions of years more.

In fact, this is exactly the kind of life system that astronomers believe could exist on icy moons in the outer solar system. Enceladus, for example, also has hydrothermal vents beneath its frozen crust that have exhibited traces of organic compounds. If the Sun were to vanish, a new icy Earth would become startlingly similar to these other worlds: vast stretches of bleak ice with pockets of rich life surrounding the volcanic hot-spots dotting the oceanic abyss.

Of course, we can’t forget the Sun’s other major effect on Earth: gravity. According to general relativity, the cessation of the Sun’s gravitational pull would also take a while to reach us. Einstein proved that the force of gravity actually travels at the same rate as light, so our planet would continue orbiting the Sun’s empty space like a forlorn groupie. But after those 8.5 minutes, Earth would be released from the Sun’s gravitational tether, and we would fly off at exactly the same speed we always move: about 30 km per second.
So would all the other planets and celestial bodies in the solar system, which means our chances of surviving the melee of space junk hurling outwards are pretty low. Provided we did manage to escape the solar system unscathed and stay out of the way of any neighboring stars, Earth could continue soaring undeterred through the vacuum of space at the same velocity. Or it could get tugged into the orbit of another star, or even swallowed up by a black hole. Either way, we won’t be there to see it.

Is force instantaneous or does it travel at the speed of light, and why?

Like is the gravitational effect felt on us by the sun immediate or does it take 8 minutes or so to be realized?

Is force instantaneous or does it travel at the speed of light, and why?

Like is the gravitational effect felt on us by the sun immediate or does it take 8 minutes or so to be realized?

Gravity is instantaneous in Newtonian physics. In general relativity it is not.

That is a common argument used against general relativity by those who do not understand it. If that is all there was to general relativity that argument would be correct. However, there is more (a whole lot more) to general relativity than a finite propagation time for gravity. Other terms such as frame dragging nearly cancel the effects of frame dragging. For example, for planets far from the Sun and moving at relatively slow speeds compared to light speed it looks very much like gravity does propagate instantaneously. This is not the case for Mercury. That general relativity explained a known defect with the Newtonian explanation of Mercury's orbit was one of the reasons general relativity won the day over Newtonian mechanics.

## Does gravity travel at the speed of light? If the sun suddenly disappeared, would we still orbit it for a while?

It disappoints me that there are 197 comments on this page so far, but I can't see one mention of Carlip's paper "Aberration and the Speed of Gravity" which actually directly answers the question.

This is disappointing because Carlip's paper shows the answer is not any of the ones given here. Yes, changes to the curvature of spacetime propagate at the speed of light, but that's not the whole story. Changes to the stress-energy tensor change spacetime in ways that exactly cancel out the aberration caused by the finite speed of propagation. That means things like planets always fall toward where their sun is, and not where it appears to be due to the finite speed of light.

Great point (would have added it myself except saw you pointed it out earlier). This is in exact analogy to electromagnetism. If you have a charged particle moving at constant velocity and fully calculate the effects of the electromagnetism propagating at the speed of light, at any given instant the electric field points away from its instantaneous position (that is where it currently is) -- not its retarded position (where it was last seen). (Granted if the particle is accelerating significantly than the effects of the acceleration will emanate from its retarded position).

A charge moving with a constant velocity must appear to a distant observer in exactly the same way as a static charge appears to a moving observer, and in the latter case, the direction of the static field must change instantaneously, with no time-delay. Thus, static fields (the first term) point exactly at the true instantaneous (non-retarded) position of the charged object if its velocity has not changed over the retarded time delay. This is true over any distance separating objects.

## If the sun suddenly disappeared, how long would humans be able to live without it?

At least nine minutes. After that the earth would go hurtling through the void no longer held in orbit by the sun. Complete loss of solar input means a drastic upset to the Earth's energy budget.

Since the seasons take less than a few months to change the cooling would be rapid. Those people with access to reliable energy stores like nuclear reactors would survive longer but eventually a massive ice age would ensue. That would take a lot longer but such models assume the sun's constant energy input.

For sure it would suck and billions would probably die within days to weeks.

Edit: since it keeps getting asked: /NO there would be no practical change in the Earth's gravity/. The sun is pulling so gently on you it would be impossible to notice the shift without sensitive instruments.

It's still really, really, hugely, far away

Same reason, it will stay almost exactly where it is now.

What if we move the earth away from the sun matching those 9 minutes to keep up with the light?

That would mean we're moving the earth at faster than the speed of light.

What if we move the earth at the speed of light?

Weɽ both be moving into our own shadow, and even if zig-zagging around the light would get dimmer and dimmer leading to icy death, just slightly slower (as in adding hours not weeks or months).

## What would happen to you if gravity stopped working?

Gravity, in the form of gravitational waves, is on a lot of people's minds at the moment.

We have all experienced the force of gravity. It is what happens to you when you jump up into the air. Disappointingly for anyone with ambitions to be Supergirl or Superman, we tend to fall right back down to the ground.

But what if we could switch gravity off?

Physics is adamant that this could never actually happen. But that has not stopped people exploring the idea. Here, based on the collective wisdom of several experts, is our best guess at what would happen to you if gravity suddenly vanished.

Jay Buckey, a physician and one-time NASA astronaut, explored how the absence of gravity affects the human body in a short Ted-Ed lecture.

Wounds take longer to heal and the immune system loses its strength

Buckey says that our bodies are adapted to an Earth-like gravitational environment. If we spend time living where gravity is different, such as on board a space station, our bodies change.

It is now an established fact that astronauts lose bone mass and muscle strength during stints in space, and their sense of balance changes.

An absence of gravity brings other problems, as Kevin Fong explains for Wired. For reasons not entirely clear, our red blood cell count falls, bringing on a form of "space anaemia". Wounds take longer to heal and the immune system loses its strength. Even sleep is disturbed if gravity is weak or absent.

That is just what happens after a short visit to space. "What if you were to grow up without gravity?" Buckey asks. "What about the systems that depend on gravity like your muscles, or your balance system, or your heart and blood vessels?"

There is good reason to believe the human body would develop differently.

Buckey points to an experiment in which a cat grew up with one eye permanently hidden behind an eyepatch. The cat was rendered blind in the eye as a result. The circuitry that would have connected it to the brain's vision processing regions failed to develop, because the eye was not processing any visual information: a very literal example of the old phrase "use it or lose it".

Earth's atmosphere and its oceans, rivers and lakes would be one of the first things to drift away into space

It seems likely that the rest of our bodies would respond similarly. If gravity was not around for our hearts, muscles and bones to respond to, our organs would almost certainly develop in different ways.

That said, if gravity did get switched off we would have more pressing things to worry about than the long-term effects on human development.

Karen Masters, an astronomer at the University of Portsmouth in the UK, has explored the immediate physical consequences of losing gravity on Ask an Astronomer. The first problem is that Earth is rotating at high speed, rather like the way a weight on a string rotates if you spin it around your head.

"'Switching off' gravity is analogous to letting go of the string," writes Masters. "Things not attached to the Earth in any other way would fly off into space in a straight line that would take them away from the surface of the Earth."

Anyone unfortunate enough to be outside at the time would quickly be lost. People inside buildings would be safer, because most buildings are so firmly rooted to the ground that they would stay put even without gravity &ndash at least for a while, Masters writes.

Anything else not nailed down would also float off. Earth's atmosphere and its oceans, rivers and lakes would be one of the first things to drift away into space.

Eventually there would be no clumps of matter, like stars or planets, anywhere in the Universe

A lack of gravity would eventually take its toll on our very planet, writes Masters. "Earth itself would most likely break apart into chunks and float off into space."

A similar fate would befall the Sun, according to this video by DNews. Without the force of gravity to hold it together, the intense pressures at its core would cause it to burst open in a titanic explosion.

The same thing would happen to all the other stars in the Universe. However, because they are so far away, it would be years before the light from their death throes reached you.

Eventually there would be no clumps of matter, like stars or planets, anywhere in the Universe. There would just be a diffuse soup of atoms and molecules, drifting around not doing anything much.

This scenario &ndash which just to repeat, could never happen &ndash illustrates just how fundamental gravity is to the workings of the Universe. Without it, nothing interesting like planets or BBC websites could ever exist.

Oh, and of course we'd all die

Gravity is one of four fundamental forces that govern our Universe.

The other three are just as crucial. Without electromagnetism and the strong and weak nuclear forces, atoms themselves would fall apart.

But gravity is the only one that is truly a household name, which is perhaps why we are so fascinated by ideas like antigravity &ndash and why the discovery of gravitational waves is so exciting, even if it never touches any of our lives directly.

## As Saturn's iconic rings disappear, it's on the verge of losing its largest moon as well — at a rate that's 100 times faster than originally anticipated

Originally astronomers estimated that Titan was moving away at around 0.1 centimeter per year. New results published in Nature Astronomy show that it may actually be moving away at around 11 centimetres per year &mdash a 100 fold increase.

This image is a composite of several images taken during two separate Titan flybys on Oct. 9 (T19) and Oct. 25 (T20) in 2006 NASA

In another 100 million years, the rings may disappear altogether, according to the study published in Science Direct.

The relationship between a planet and its moon
The Earth and its moon aren&rsquot perfect either. In fact, like every other child-parent relationship, the Moon is always moving away from its parent planet at the rate of around 3.8 centimetres per year.

The Moon&rsquos gravity on Earth is what creates tides &mdash and the occasional werewolf urban legend. In turn, the friction from the process distorts the Earth&rsquos own gravitational field pulling Moon forward back into its orbit. You would think that keeps the Moon in line. However, the entire process is what gives the Moon more energy to gradually move farther away.

Fear not, there&rsquos no chance of Earth &lsquolosing&rsquo its Moon. They are destined to be together until they&rsquore eventually engorged by the Sun in another six billion years.

Hunter's Full Moon seen from the International Space Station (ISS) NASA

Titan, on the other hand, has slowly been moving away from Saturn over the past 4.5 million years. It now stands 1.2 million kilometres from Saturn&rsquos reach. Unlike the Earth, Saturn&rsquos gravitational pull is a little weaker. Which makes sense, since it&rsquos made out of gas &mdash not rock.

What makes Titan special is that its the only moon in the solar system with an atmosphere. It&rsquos covered in rivers and seas of liquid hydrocarbons &mdash like methane and ethane. Scientists believe that below the thick crust of water ice there may actually be a liquid water ocean capable of supporting life.

The Moon is not the only thing Saturn is losing
Saturn&rsquos gravity isn&rsquot strong enough to hold onto its moon, but it&rsquos certainly strong enough to pull down its iconic rings. The rings are being pulled into Saturn by gravity as a dusty rain of ice particles under the influence of Saturn&rsquos magnetic field.

An artist's impression of how Saturn may look in the next hundred million years. The innermost rings disappear as they rain onto the planet first, very slowly followed by the outer rings. NASA/Cassini/James O'Donoghue

These particles are caught in an everlasting balancing act between the pull of Saturn&rsquos gravity &mdash which wants to draw them back into the planet &mdash and their orbital velocity, which wants to fling them outward into space.

Currently, scientists are tracking how ultraviolet light from the Sun charges the ice grains and makes them respond to Saturn&rsquos magnetic field. They believe that varying exposure to sunlight should change the quantity of ring rain.

## What is our atmosphere made of?

The atmosphere, as we know it, is a protective layer of gases that envelop the Earth. It consists of a number of gases, including nitrogen (78%), oxygen (21%), argon (0.93%) and traces of carbon dioxide, hydrogen, helium, and other noble gases. The atmosphere is held in place above the planet (as is true of any other celestial body with an atmosphere) due to its gravitational force, which keeps it adhered.

### Importance of the atmosphere

The benefits of having an atmosphere are too extensive to list. The fact that most of life as we know it depends on it says plenty about the atmosphere&rsquos importance to the planet. In addition to being an abundant source of oxygen, i.e., the lifeline of most life forms on Earth, the atmosphere also acts as an insulating layer that protects us from harmful solar and other cosmic radiations.

Our atmosphere divided into different layers Photo credit: dimair/ shutterstock

## 1 False: We Understand What Life Is

Scientists keep sending robots to other planets in the hope of discovering the answer to that great existential question: Does life exist elsewhere in the universe, and if so, could we bone it?

But here's a more basic question we should be asking: What is life?

That's easy, you might think. People, birds, magnetic super-frogs -- all living things. Chairs, rocks, Senator Ted Cruz -- all lifeless, unthinking, inanimate objects.

But it turns out that there's a considerable "gray area" between "alive," and "not alive," and for once, we're not talking about zombies. In fact, that gray area encompasses a large swath of the biosphere, at least on a smaller-than-visible level. For example, there's constant disagreement among scientists about whether or not viruses are alive. Viruses, such as those responsible for influenza, are different from bacteria, in the sense that they don't have cells, but they do have DNA, and they can still mess you up if they get into your body.

So they're alive, right? Not so fast! Viruses don't breathe, or eat, or anything else that's usually an indicator of a living organism. And they can exist forever in the wild because, if you're not alive in the first place, you can't die. The one thing they do that usually defines a "living thing" is reproduce. And they can only do that inside an already-living cell.

Right now, scientists are flirting with the idea that viruses fall into the "alive" category, but there are also viroids, which are organisms (?) that are even simpler than viruses, and mostly affect plants. Even below viroids, we have prions. Prions are basically just messed-up proteins, and they're responsible for exotic diseases like Mad Cow Disease. Are those bastards alive? Nobody really knows! Which is a big deal for medicine, because prions are like some sort of horrible reverse-Predator: if they're not alive, we can't kill them.

Scientist Martin Hanczyc has created some little chemical blobs that he calls "protocells," which move around, take in energy from the environment, and grow. Are they alive?

Oh, but this is all just fruitless rumination about tiny, invisible stuff. We don't need to stress about whether or not like, buffalo are alive. D-do we?

Scientists have found that the movement of buffalo herds can be pretty reliably predicted by the same rules that govern particles in a gas. And swarms of ants actually move very much like liquids. So to what degree is life that different to the inanimate crap that floats around us all day?

And holy crap, what if scientists find out that you behave strangely similar to like, an asteroid field? A gassy, lazy asteroid field? What does that mean for your life?

And on that note, we're going to go get high and stare at our own hands for a while.

Saikat Bhowmik is a kid who has grown a beard to look like a grown-up. He has a grown-up account at Twitter and a childish YouTube channel.

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