If fusion reactions were to suddenly shut off in the sun, how would we be able to tell?

Answer 1

The sun would go out 8 minutes later, turn into a neutron star and we will be irradiated by lethal radiation.

The sun is superheated plasma and the sun circulates its plasma. Gravity pulls it in, which makes it hotter up to the point of fusion. This energy is so powerful that it can overcome the huge power of gravity and rise to the surface, before it is caught by the sun's gravity. When the sun gets a "tummy ache" then it shoots out more energetic streams creating solar flares. Under normal conditions some particles are so energetic that they can escape the sun, this is the solar wind. It is all driven by the circulating plasma and the fusion reaction.

Stop this fusion reaction then all solar flares will collapse, the solar wind will disappear so in 8 minutes earthlings will know something is wrong.

Seconds later the only force on the sun will be gravity and it will collapse upon itself. The sun is too small to form a black hole so it will collapse to the size of a neutron star and all the light will go out.

The continued gravitational collapse will break up some particles, most of the subatomic particles won't be strong enough to escape, but x-rays and gamma rays can. Once the new neutron star reaches a point of equilibrium then the radiation produced will slow down. Until it reaches that point though the new neutron star will be spewing forth only lethal types of radiation.

After a few hours
All weather is solar driven, so the winds would die and any clouds would stop. The temperatures would equalize so those clouds would start to move toward the poles (north for the northern hemisphere, and south for the southern hemisphere). This wind would be very weak though and once the temperatures are equalized it will die.

The radiation may not be enough to kill all life on earth, but it will cripple it making it weaker and just decreasing the time for the death spiral. New mutations will appear and die out. Most wouldn’t have survived any way and the rest will face conditions that are too hard to live for very long, but they may hang on long enough to see the rest of the animals die.

Plants do have storage cells so they will take time to die. To them it will seem as if a sudden winter came upon them. They will shed their leaves and go dormant. The evergreens will still be trying to get light and expending energy to hold out their leaves so their reserves will drop faster and they will start to die first.

After a few days
When the plants go into winter mode they will drop all of their leaves (it takes too much energy to hold them), and all of their fruit and vegetables.

The cooling will be too fast for animals to adapt so they will suffer the full effects of the never ending weather.

After a week
Meanwhile most animals will go insane soon. We need light to see; even nocturnal animals magnify the existing light. Once the sun goes out then the only bodies that will have any light are the gas giants of Jupiter and Saturn, because they are emitting radiation. At first it will only seem like night to the animals, but they live by circadian rhythms so once those rhythms are disrupted they will start to get restless, irritable and soon they will go insane.

Nocturnal hunters will do well at first, but those that hunt by day; like the hawk and the eagle when soon starve. The restless animals will make them more skittish, and harder to hunt, when they get irritable they will become more dangerous to hunt, and when they go insane they will be extremely hard to hunt, until they exhaust all of their reserves and collapse. The nocturnal predators will do well now, but the diurnal ones will be starving to death. As more animals die the scavengers will do well, but vultures need to see so they won’t be around for very long. Without their competition the insects will thrive. Most predators will not eat a corpse that they or their fellows didn’t kill, because it could be diseased. Of course hunger will drive some of them to attempt it, but not until they are in bad shape.

Hibernating animals will gorge themselves and go to sleep. With the cooling temperatures they will never wake up. They will slowly starve to death. Those that awake will be too weak to gather food, so unless they have good resources at hand they will die. Oddly enough these animals that start in the winter cycle will do better.

A lot of insects thrive on the dead and don’t need much light, a lot of them also hunt and eat each other, and when times are lean cannibalism is a good tactic. They will survive the longest, which means those darn cockroaches will be fat and happy. Butterflies will either starve to death or try and go into a cocoon state. Those that make it will slowly die; those that don’t will just die faster. Insects like fly’s and cockroaches will live the longest. Preying Mantis won’t be able to find food since they are adapted to hunt in the daytime. Many will hang on and try hunting at night though. Those insects that hibernate will go into hibernation, a sleep from which they will never wake up.

Humans will survive for a while, long enough to make the human race's chance to survive decrease. Power plants will run, heaters will work, and even tidal wave generators will still be working. So scientists we have ample time to determine just what happened. They may even have enough time to send a probe to the sun to see what is wrong. These scientists will also know that unless some drastic measures are taken humanity will die. A lot of people are going to figure it out as well, and so starts the riots.

After 6 months
Power will become the most important thing in the world, right after food and fresh water. With the cooling earth the remaining clouds will either rain themselves out, or fall apart in a shower of ice cubes. The weather cycles will be gone so hydroelectric power plants will start to fail, as will wind power generators. Solar power would have gone out long ago, starlight can’t cut it. Starlight just isn’t strong enough to generate much heat, so the weather systems and the wind will all die away. The moon will keep the tides running and the neutron star will keep the earth and the other planets in orbit. There will be no loss of gravity in the sun, only of light and heat.

Wars will quickly erupt as everyone tries to gather their limited resources. People in rural places will be even worse off, the only stocks of food will be in warehouses near the city, so they will flee to the cites, churning the riots to a frenzy. Some groups will be able to gather resources and hold on to them, most of these groups will have military resources. Which also means they can attack each other. As the resources dwindle then society will fragment and go to war.

After 8 months
Meanwhile inside the cities the food stocks will quickly run out, stores will be looted and the police will be overwhelmed. Cities will become death traps with an every man for yourself attitude.

Fuel supplies will dwindle, as will supplies of wood. To get either you have to venture into the world and face possible attack. The last of civilization will gather around the nuclear power plants. Radiation damage and cancer has become a problem now. The sun hasn’t stabilized yet so the radiation will keep on coming down.

By now most animals are dead. The surface fish died a while ago, and then the oceans started to freeze like a pond. Ironically this will help hold in the heat, but new oxygen won’t be coming in. With the end of weather cycles all water will run downhill, into the ocean or underground. Lakes will drain, what can’t drain will freeze over. A lot of water will simply go underground and freeze at the frost line making drilling very tough. As civilization falls few boats will move and when the ocean’s start to freeze that number will dwindle. No more deliveries of food, oil and goods.

Iceland will be thriving. Most of their heat is generated by geothermal actions, which won’t stop. They are used to the cold and are a small and isolated group so they can come together and survive. You would think that Hawaii would do well, but most of their goods are imported and they are not set up to handle geothermal energy. They will try and being so isolated they might succeed, for a while. But, shortly they will run out of supplies and they won’t be able to sustain themselves.

After 10 months
With the deepening cold the oceans and lakes will start to freeze deeper and deeper. The supply of oxygen will be decreased so only those fish able to live in the deep will be alive. All aquatic mammals went out with the surface fish. This means that polar bears will be starving, and since the penguins can’t go into the sea to fish they will be starving as well. As the cold continues then the lakes and oceans will freeze top to bottom. This will take longer so the fish will be the last to die.

Insects are delicate and need a certain temperature range to thrive. The flying insects (including cockroaches) will start looking for warm areas. They will hit the cities first and quickly multiply because of all the rotting corpses. They will live long enough to see the cities die. The flies will go first with the cockroaches seeking warmer places.

The isolated spots of humanity will then get an influx of insects. This influx won’t last for long because those that aren’t inside the sheltered areas will start to freeze. Ants are in hibernation or dieing off. Termites already died, only the scavengers are left.

After 14 months
Finally the world will die. It will be too cold to live anywhere. Those in Iceland will be going strong, but even they will be suffering from the heat loss and they will be forced to go underground.

Those around the nuclear power plants will try to find caves to live in so they can keep going, but it will be hard.

After 2-3 years
In a few years the atmosphere itself will start to freeze when that happens no one can go outside, no one can travel and if they are not in a safe habitat they will be dead.

Iceland can probably get enough heat to melt chunks of atmosphere to breathe, they will have been able to set up underground farms and they will still be alive, but the chill will be getting to them forcing them deeper into the crust.

After 4 years
The other isolated pockets will start to die out. Any minor problem will quickly become a life threatening one. The crews running the nuclear power plants will be cut off and start to die, but remote control can keep those plants running.

After 6 years
The only life left on the planet will be in Iceland. However, they have reached their limit. If they dig down deeper they have a strong chance of rupturing the crust, in the areas where that isn’t a problem they will have dug down as far as modern equipment can go. The pressures to collapse the holes and tunnels will be too great. Any other pocket of humanity will have met the same problem only sooner. Unable to dig deeper they will slowly starve and freeze to death.

Answer 2

Well, should you imply 'close off' to be the preventing of nuclear fusion, then we would ought to wait 10,000 years or so - if I don't forget effectively, that is how lengthy it takes vigor from the centre of the solar to arrive the skin - for something to honestly occur. We'd then be capable to inform for the reason that the whole thing is going darkish and bloodless, very swiftly. All lifestyles might quickly stop to exist, and that is the top people. Well, except the halt in vigor creation 'modifies' the solar one way or the other, main to anything extra fascinating, despite the fact that we can not precisely paintings that one out for the reason that it is bodily not possible to get a celebrity which is not fusing.

Answer 3

Without fusion, the suns diameter would change pretty dramatically. As a star uses up hydrogen, and starts fusing helium, it tends to "puff up". If fusion just stopped all of a sudden, which should be impossible, I would assume that the sun would collapse to a brown dwarf in a matter of a few days or weeks.

The long post below is incorrect, the sun is not massive enough to become a nuetron star.

Answer 4

Well according to Isaac Newton if the sun were to suddenly dissapear the affect will be felt instantaneously[spelling]. But then Albert Einstein said that that is not possible because if the affect was felt immediately, that would mean gravity travels faster than the speed of light and that is not possible. So if the sun was suddenly removed {which is impossible] it would take approximatly 8.5 minutes until the affect reaches earth.

Answer 5

The process would take millions of years. When the fusion reactions slow down the sun will gradually swell and become a red giant.

Answer 6

The sun would shrink rapidly and cool,it would end up as a big cinder floating through space. It would not have the same effect as a massive star whose fuel was all used up resulting in a core collapse!

Answer 7

Well, it would grow into a Red giant, and consume Mercury, Venus and Earth. After some time (millions of years) it will shrink and turn into a white dwarf. We would know because 8 minutes after they shut off the sky will turn red, and flash boil the oceans shortly before killing all life.

Answer 8

Nothing happens 'suddenly' in space. We would have plenty of warning. Not that's much we can do about it though.