How can the sun be on fire for billions of years and still be the same size now as it was then?

Answer 1

The size of the sun is a balance between two forces. Gravity tries to make it smaller, but the internal "fire" tries to expand it. As it loses mass, it could cool down and maintain a certain size. But I think the real answer is it has not stayed the same size.

Answer 2

The sun is actually getting 4 million tons lither each second. But at the same time, its heat output is slowly creeping up, and it will swell up to over 100 times its current diameter over a relatively short period in about 4 billion years. The repartition of mass inside changes as helium accumulates in the core, and the red giant phase will start when the pressure and temperature inside the core is able to ignite helium fusion.
So, the sun is getting lighter, hotter, and the outer layers are expanding. All this is done very slowly, so you think it looks the same. But it was smaller, colder, and heavier a few billion years ago. The earth and the other planets were also a bit closer to the sun back then than they are now.

Answer 3

First of all the sun has not remained the same size for eternity, all stars have a 'life-cycle'. Inithially it began as a smaller star in a nebula, then it grew over the last 4 billion years to what it is today. In the future the sun will expand and finally collapse to form a small white dwarf. But this will take many billions of years.
Secondly, it is not tecniqually burning, its hydrogen is under going 'nuclear-fusion' where the hydrogen molecules react with one another.

Answer 4

Most people think of space as a total vaccuum. It is not, in fact. There are gases, and dust, and other particles. There are even regions of abundant oxygen and nitrogen, where entire solar systems have the climate and life support capabilities of the earth - that means you could fly a plane through space in these solar systems! You could build a floating house and use solar power to grow food, millions of miles away from any planet!

The sun sucks the dust and debris in and is constantly replenished, using the space dust for fuel. When the supply of space dust begins to be all used up, then the sun will expand in an effort to trap more space dust further out. Unfortunately, this includes the Earth.

Or is it unfortunate? Scientists are realizing the amazing defensive powers of planets. It is theorized that when the sun begins expanding, that will send a gravitational signal to earth's core and magnetic field, and cause the earth to recede further out into the solar system, to about where Jupiter is now. Life on Earth will thus be preserved.

Love, Jack.

Answer 5

The sun is not on fire. It radiates many types of stuff. The mass that it loses through its reactions is insignificant to the amount of mass it has. Although if anyone was around to measure what size it was a billion years ago, I really dont know....

Answer 6

It isn't on fire. Its energy comes from nuclear reactions and not fire, which is a chemical reaction. Nuclear reactions use very much less matter than chemical reactions. The Sun is so big that it has enough matter to keep up those nuclear reactions for billions of years.

Answer 7

It's not the same size now as it was then. Stars are all a fireball fight between their massive gravity and the explosive power of the nuclear fusion reactions that keep them burning. We are living in a very short (cosmicly) window that allows life in a planet orbiting a giant fusion reaction taking place in orbit of a massive super dense cloud of helium and hydrogen that is our sun. And that's what we call a star. And stars grow and shrink in size.

Answer 8

It's all in the fuel. Also, the sun is not solid. You are looking at a nuclear fire ball held together by gravity. The fuel is expending it self but because it is all gaseous you can't tell by looking at it.
Vaya con DIOS

Answer 9

Du to the nuclear gas that formed the earth & the planets billions of years ago

Answer 10

How come you know the size of the sun, did anyone get up and measure it, and live to tell the tale, without being burnt alive. However. maybe we all adjust, and are shrinking slowely. Who knows. How come you know the sun is the same size. You are amazing.