since the suns energy is beign created by nuclear fusion isnt there a risk of something fucking up and a giant nuclear explosion wiping out the universe

no

and why not

There's only so much energy in the sun (or any star). Certainly not enough to wipe out the universe. And a star is basically just one big uncontrolled nuclear reaction ... except that it is controlled by one thing: its own gravity. This keeps it from expanding outward past a certain point. It's also limited by time, because after a billions and billions of years, it simply runs out of fuel and dies.

I don't think you have an accurate grasp of the vastness of the Universe or the actual energy relased in nuclear reactions. Let's imagine for a moment that the sun's gravity is taken out of play for a moment and there is no force left to contain the energy released from the fusion reactions. The fusion reactions would continue on for a long time until the sun ran out of fuel which would probably take a few billion years. The damage done by the nuclear reactions would most likely be the elimination of most if not all the planets in this solar system but not much more. Now there are millions of solar systems just like ours in this little galaxy of ours called the milky way. There are also uncountable numbers of galaxies just like ours which make up the universe which is continuously expanding outward making new galaxies. So as you can see the damage done by the sum would be so insignificant in the grand scheme of things that it would be infinitely less then the damage I do (to the earth) when I crush an ant with my foot. =)

[This message has been edited by brainuser (edited 12-10-2002).]

yeah ktulu is right. believe it or not, the sun burning IS "something fucking up with the giant nuclear explosion". its constantly happening. nuclear bombs are huge, but so is the universe, and when everything is so far away from the sun, nothing gets blown up or anything.

like ktulu said, it's uncontrolled fusion. what you're worried about is constantly already happening.

damn that little fucker posted like 2 minutes before me.

(just to explain any detection of redundance)

i actually didnt mean universe but galaxy sorry i also mean one massive nuclear explosion the whoe sun causing one giant one

[This message has been edited by r0k (edited 12-10-2002).]

Think about the size of our sun. Good, now think about the size of the universe, or even our own galaxy. The comparison is like comparing an electron to the size of our star ( about ). To make something that would destroy the entire galaxy, we would need a VERY VERY efficient way of transforming matter into energy. Even if we where to get 100% transformation of matter to energy, it would take a lot of matter to annihilate our galaxy. At least this is my understanding of this matter anyways. Please correct me if I�m at fault in my statement.

And besides, stars go pop every now and again, it�s called a (super)nova.

On the rare occasion that a star does become unbalanced and goes up like a giant nuke it is called a supernova. The force from an explosion that size is enough to disrupt nearby star systems. The last supernova was a few years ago, and it was so powerful that even though it was practicaly on the other side of the known universe it was visible to the naked eye. In fact it was the brightest star up there.

Supernovas only occour about once in a hundred years, so it will probably be a while before the next one is seen.

i want a nearby star to go supernova and kill us all *licks lips*

why worry about the sun when we're being pulled in to a black hole! AH!!!!

every time a nuclear explosion happens on the sun it is far bigger than the earth.

Nuclear weaponry works on nuclear fission, not fusion. The energy output in fusion is vastly greater than that of fission.

H bombs are fusion bombs.4H>He

Boom

Actualy in H bombs 2 Deterium atoms form 1 helium atom.

Deterium is of course an isotope of H, with a proton and a neutron.

Um the sun is a giant constant nuclear explosion! period end of discussion. A supernova is not what happens when it "explodes" accidentaly.

A supernova occurs when a star runs out of hydrogen fuel(it gets very large as it starts to run out the sun will fill the solar system when this happens). It starts fusing helium, then it begins to collapse because it cannot give out enough energy to hold itself up under it's own gravity. As it collpses it begins to fuse larger and larger nuclei until it reaches iron (isotope?) which is the most energetically stable nuclei possible. This is the deciding point, some stars aren't massive enough and they become dwarfs, burned out highly dense ex-stars. However if a star is massive enough it reaches this maximum crunch and then goes supernova, I don't know off hand what the physics are but all the matter gets expelled in an explosion that thankfully creates all sorts of nuclei larger than iron. What is left behind is a neutron star, a ball of neutrons so densely packed that a tablespoon full weighs hundreds of tonnes. Some supernovae become black holes and some become pulsars. I'm not totally up to date on this but I can go find out more if anyone has any questions about it and no access to the books.

I didn't mean that a star would go up 'accidentaly'. There is a very logical procession that leads to a nova or a supernova.

What you described is a nova, a much more common occourance. When there is enough force exerted on the iron core of the star the iron will fuse too creating all of our heavier elements. All that extra force needed to fuse iron and distribue a good sized chunk of it across the galaxy comes from an out of control nuclear reaction.

Stars are actualy very controled, they have naturaly reached a stabilization point where things happen at a given, mesurable rate. When circumstances change so do the stabalizing forces.

Ok then prom what is the distinction between a nova and a supernova?

Why must I always do the research? Why can't someone else do it for a change? And don't tell me it's because I'm a mod, research isn't in my job discription. That said, here's your frigging research:

(from the World Dictionary)
Nova: a star that suddenly becomes much brighter and then gradualy fades to its normal brightness, over a period of several weeks, months, or sometimes years
Supernova: a nova far brighter than an ordinary nova, being from 10 to 100 million times as luminous as the sun. A supernova appeared in 1885 in the Andromeda galaxy and in a few days radiated more light than the sun does in a million years.

Now for the meat of the matter.

from: http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_4a.html
Classical Novae

The classical nova outburst -- often simply referred to as a nova -- arises from a nuclear explosion in the surface layers of a white dwarf. It does not involve the core of the star as is the case in supernovae.

The classical nova outburst arises as follows:

• A white dwarf consisting of elements heavier than hydrogen, such as carbon and oxygen, accretes hydrogen-rich matter from a close companion star.
  
  
• The matter passes through an accretion disk that surrounds the white dwarf, before spiraling down onto the white dwarf.
  
  
• This transfer of matter from the companion star to the white dwarf is a continuous process: Fresh matter arrives at the outer edge of the accretion disk from the companion star, spirals through the disk, and accretes onto the white dwarf.
  
  
  
• When about 1/100,000 of a solar mass of hydrogen-rich matter has been accreted, the temperature and density at the base of the accreted matter become so severe that a nuclear explosion is triggered and the white dwarf's surface layer is ejected at speeds of about 500 miles/second or greater (2 million miles per hour or greater).
  
  
• The explosion and ejection are accompanied by an intense brightening. Hence, the name nova, meaning "new" (i.e., the star becomes visible across interstellar distances).
  
  
• Maximum brightness lasts only a few days. The brightness then diminishes and, in the course of several months, returns to the pre-outburst level.
  
  
• Mass transfer and accretion then resume until another nova outburst occurs.
  

Typical time intervals between outbursts are several thousand years. The white dwarf will experience outbursts as long as the companion star is able to furnish fresh hydrogen-rich matter.


from: http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_4c.html
Supernovae of Type I

A supernova of type I is an explosion in which a white dwarf destroys itself.

The white dwarf is more massive than the Sun, consists predominantly of carbon and oxygen, and accretes matter from its companion relatively rapidly. Any nova outbursts that occur on the white dwarf are relatively weak and eject only little matter. Consequently, the white dwarf grows in mass:

• When the accretion has raised the white dwarf's mass to the critical mass of about 1.4 solar masses, the density and temperature in the star's center become so severe that carbon starts burning explosively.
  
  
• Within roughly one second, the burning front moves all the way to the surface, making the entire white dwarf one huge nuclear fireball.
  
  
• The entire star explodes and destroys itself. There is no stellar remnant.
  
  
• All of the star's matter -- namely, the products of the nuclear burning (iron, nickel, silicon, magnesium, and other heavy elements) plus unburned carbon and oxygen -- are ejected into space at speeds ranging from about 6,000 to 8,000 miles/second (20 to 30 million miles/hour).
  

Unlike supernovae of type II, the matter ejected in type I supernovae consists almost entirely of the heavier elements. There is no, or almost no, hydrogen.


from: http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_3.html
Supernova Explosions

Stars that are born with masses greater than about eight solar masses end their lives in gigantic explosions called supernovae.

The Structure of an Evolved, Massive Star

Before discussing supernova explosions, let's look once more at the structure of the highly evolved star of 20 solar masses that we showed earlier:

Focus on the star's iron core. It's very compact, with a mass somewhat less than 1.4 times that of the Sun, but a size of only about two-thirds that of the Earth.

Once a star has reached this structure, the nuclear burning history that we have discussed draws to a close. The iron core will not ignite to induce further nuclear burning as has happened earlier to the helium, carbon-oxygen, and other cores. The reason is that iron can't burn.

Nuclear burning (just like chemical burning) is possible only if the reactions release energy. However, the fusion of iron with other nuclei to make still heavier nuclei requires the input of energy. This input of energy for making the heavier elements becomes available only during the explosion that is about to occur.

The fact that iron does not burn leads to the collapse of the star's iron core and the explosion of the star's outer envelope. We shall describe this development in three sections:

Supernova Ejection
Supernova Remnant
Stellar Remnant
--------------------------------------------
Supernova Ejection

As the mass of the star's iron core approaches 1.4 solar masses (due to continued silicon and sulfur burning in a thin shell adjacent to the iron core), a dramatic sequence of events is being triggered:

Iron Core Collapse

• Gravity, which up to now was balanced by the outward force of the pressure, decisively gains the upper hand and the iron core collapses.
  
  
• In less than a second, the core collapses from a size of about 5,000 miles to one of about a dozen miles, and an enormous amount of energy is released. This collapse happens so fast that the star's outer layers have no time to react and participate in it.
  
  
• The amount of energy that is released during core collapse is truly gigantic -- it is equivalent to the energy produced by 100 stars like the Sun during their entire lifetimes of more than 10 billion years!
  
  
• Most of the energy released during the collapse of the iron core is carried off into space by elusive particles called neutrinos. A small fraction of the energy is deposited in the lower layers of the envelope surrounding the core and triggers the supernova explosion.

Envelope Explosion

• The energy deposited in the lower layers of the envelope creates a superstrong shock wave that runs outward through the envelope toward the star's surface.
  
  
• As the shock wave runs outward, it heats the envelope, induces explosive nuclear burning, and ejects the envelope at speeds of thousands of miles per second (i.e., in excess of 10 million miles/hour).
  
  It is during this phase that elements heavier than iron are being manufactured.
  
  
• When the shock wave reaches the star's surface, it very quickly heats the surface layers and brightens them. Within a day or two the exploding star becomes brighter than a billion Suns.
  
  This is the moment when distant observers first learn that a supernova is exploding (unless they have been lucky enough to detect some of the neutrinos that were emitted earlier during core collapse). A star appears where, as viewed over the great distances of interstellar or intergalactic space, none was seen before -- hence, the term nova, which means "new."
  
  
• The result of these events is a compact stellar remnant and a rapidly expanding gaseous shell.
  
  The stellar remnant is a neutron star or a black hole.
  
  The expanding gaseous shell plows into the surrounding interstellar medium, and pushes, compresses, and intermingles with it. Such regions of the interstellar medium are known as supernova remnants.
  
  
• After some weeks, the brightness of the explosion diminishes, although the supernova may remain visible for many months or years, even across intergalactic distances.
  About 20 to 30 supernovae are discovered each year in galaxies beyond the Milky Way. Most are too faint to be seen without a telescope due to their great distances.

Note: Astronomers call the kind of supernova we described a "supernova of type II."

--------------------------------------------
Supernova Remnant

The gaseous shell ejected by a supernova plows into the surrounding interstellar medium, compresses it, intermingles with it, enriches it with freshly synthesized heavy elements, and forms what is called a supernova remnant.

Supernova remnants may be observed for hundreds of thousands of years as often beautiful, visual objects, but also as emitters of radio waves and X-rays.

Close to 150 supernova remnants have been detected in the Milky Way and more than a hundred are being discovered every year in distant galaxies.

Approximately half a dozen supernova remnants have been associated in the Milky Way with supernovae observed during historic times, such as Tycho's and Kepler's supernovae, which were observed in 1572 AD and 1604 AD, and the supernova of 1054 AD.

--------------------------------------------
Stellar Remnant

The star's collapsed core is not a normal star. It is a neutron star or a black hole.


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I RECOMEND READING THE ARTICLES FROM THE HYPERLINKS, THERE ARE EXPLANATORY PICTURES.

It looks that for the most part you were right. Well it has been a few years since I went over this stuff, so naturaly my memory is a little mixed up (it seems that I was mixing some elements of type I with type II). But far be it from me to stick to a point when I was wrong. That would be downright unscientific of me.

[edit]massive formatting[/edit]

[This message has been edited by Prometheus (edited 12-13-2002).]

Thanks prometheus.....