How long will it take the sun's light to fade away?

Answer 1

The Sun is about halfway through life, during which nuclear fusion reactions in its core fuse hydrogen into helium. Each second, more than 4 million tonnes of matter are converted into energy within the Sun's core, producing neutrinos and solar radiation; at this rate, the Sun will have so far converted around 100 Earth masses of matter into energy.

The Sun will spend a total of approximately 10 billion years as a main sequence star. The Sun does not have enough mass to explode as a supernova. Instead, in about 5 billion years, it will enter a red giant phase, its outer layers expanding as the hydrogen fuel in the core is consumed and the core contracts and heats up.

Helium fusion will begin when the core temperature reaches around 100 million kelvins and will produce carbon, entering the asymptotic giant branch phase.

Earth's fate is precarious. As a red giant, the Sun will have a maximum radius beyond the Earth's current orbit, 250 times the present radius of the Sun. However, by the time, the Sun will have lost roughly 30% of its present mass due to a stellar wind, so the orbits of the planets will move outward. If it were only for this, Earth would probably be spared, but new research suggests that Earth will be swallowed by the Sun owing to tidal interactions.

Even if Earth would escape incineration in the Sun, still all its water will be boiled away and most of its atmosphere would escape into space. In fact, even during its current life in the main sequence, the Sun is gradually becoming more luminous (about 10% every 1 billion years), and its surface temperature is slowly rising. The Sun used to be fainter in the past, which is possibly the reason why life on Earth has only existed for about 1 billion years on land. The increase in solar temperatures is such that already in about a billion years, the surface of the Earth will become too hot for liquid water to exist, ending all terrestrial life.

Following the red giant phase, intense thermal pulsations will cause the Sun to throw off its outer layers, forming a planetary nebula. The only object that will remain after the outer layers are ejected is the extremely hot stellar core, which will slowly cool and fade as a white dwarf over many billions of years. This stellar evolution scenario is typical of low- to medium-mass stars.

See link for a pictorial representation.
When a medium-sized star such as our Sun begins to run out of hydrogen to fuel its nuclear fusion furnace, it turns to helium for fuel and swells up to many hundreds of times its normal size, becoming a red giant.

As the star grows, the expanding outer layers engulf and destroy the inner planets. The star eventually loses its outer layers completely and forms a planetary nebula, leaving behind an extremely dense core approximately the size of Earth, called a white dwarf.

Answer 2

Our Sun is about 4.57 billion years old. About half way through it's life. The Sun will slowly turn into a red giant in about 4.5 billion year and about two billion years later, it will shed it's outer layers and become a white dwarf.

For the Earth, this means that when the Sun turns into a red giant, the Suns envelope will expand until it nearly touches the Earth.

For life on Earth, it's not as simple, in about a billion years time, the Sun will have increased it's temperature to such a degree that it will be impossible for life to exist on the surface as it would have become so hot that all water would have boiled away.

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The information I understand is the Earth is 4.5 billons years of age. From what I understand the formation of a galaxy can take upwards to .7 billion years. If so the completion of the Earth plus the age of the Earth would be 5.2 billion years. A yellow dwarf star should expand into a red dwarf at 6 billion years. As the sun expands into a red dwarf it will easily encompass the Earth along with planets as far away as Mars. This phenomenon could occur as early as 800 million years from now. Although some theories state as the red dwarf expands the Earth may be knocked backward possibly to a safe distance from the sun. The likelihood is if even this should occur, the distance of the Earth from the red dwarf would not be conducive to life on the planet. This is of course if this does even happen as the expectancy is the Earth when encompassed by the sun will melt into nothingness except for perhaps some vapors which seep into the solar system.

Answer 3

About 5 Billion Years. Although a couple billion years before that happens it will first swell into a red giant which will grow and grow in size in earth's sky until it eventually consumes the earth.

After that it will violently expel its outer surface into space and slowly blow most of its matter away until all that is left is a small, remnant white dwarf star.

Answer 4

It will take approximately 8 minutes and 20 seconds for the Sun's light to travel from the Sun to the Earth. After the Sun dies in about 5 billion years, it will gradually fade away over a period of billions of years.

Answer 5

Altogether about 10 thousand million years before it becomes red giant star.

It's about half way along that path now.

Then it will become a white dwarf star. A white dwarf star is a "dead" star with no "fuel" left, but it remains hot for billions of years.

Answer 6

Scientists expect that the sun will remain pretty much the way that it is now for another 5-6 billion years. After that, we believe that the sun will expand, and probably consume the inner planets. At that time, all life on Earth will be destroyed, and the Earth itself may be destroyed.

The expected lifespan of stars is almost completely determined by their size and mass. Our sun is, we believe, too small to go "nova" and explode, the way large stars do.

Answer 7

Nobody really knows, since we haven't been around long enough to observe the entire life cycle of a star. By putting together clues from the stars that we can observe, I've seen estimates that range from 6 billion to 10 billion more years, based on an age of 4.5 billion years so far. Stars are apparently fairly short lived, compared to the galaxies in which they are formed and live out their lives. If the sun was a very large star, it could have been gone long ago, as the bigger the star, the faster it burns up its initial fuel, so that some stars are done in only 10 million years! Ours is probably going to be around for a very long time to come.

Edit: Through the use of modern un-melting magnets, estimates have shown that the suns life span can be infinite.

Answer 8

The Solar System already lived almost 5 billion years; it may live several billion years more. It is estimated that in less than a billion years, temperatures on Earth will be too hot for most kinds of life; but the Solar System as such will continue existing for quite a while longer.

Answer 9

In a few billion years the sun will expand into a red giant before imploding into a brown dwarf and fading away during a few tens of billions of years (according to some models of stellar evolution)
It takes about 15 minutes for the sun to go from sunset to all the way down. The sun starts to set at 4:30 everyday and rises at around 6:30 every morning.

Answer 10

Based on our current understanding of physics, we expect the Sun to continue pretty much unchanged for another 3 to 4 billion years as it fuses hydrogen into helium. It will then grow - abruptly! - into a red giant, and burn for perhaps another billion years, fusing helium into heavier elements like carbon and oxygen.

After that, it'll be all downhill, and the Sun will begin to cool down and collapse into a white dwarf. We don't really know how much longer it can continue as a white dwarf before it finally fades into a brown dwarf.

For us here on Earth, that's pretty academic, since the Earth itself will probably have been incinerated when the Sun expands into a red giant. Unless, of course, we move the Earth to another, younger, star. By the time we need to do that, we'll know how....