How Long Will the Sun Last?

To someone on another planet outside of the solar system, our Sun might just look like any other star. But to those of us living on Earth, it is the source of all life! Without the Sun, we would have no plants to eat or air to breathe. The Sun also heats the planet to a reasonable temperature so that life as we know it can exist.

Today, solar energy from the Sun is a viable renewable energy source. Even on a cloudy day, solar panels can collect solar energy to power electronic devices, buildings, and electric cars.

Due to its physical importance, the Sun is also an important figure in many religions. Some religions, both ancient and current, view the Sun as a Deity. For example, in Hinduism, the Sun is a god called Surya Dev. Other religious peoples built monuments to the Sun that are still around today, like Stonehenge. In many religions, the quality of light is associated with purity or piousness, and darkness is associated with evil. Some believe that is due to the life-giving qualities of sunlight.

The Sun is extremely important to our existence, so the thought of it going away might sound scary. But the Sun is a star, which means someday, it will die. But when will that happen?

When Will the Sun Die?

The Sun will officially die in about seven to eight billion years from now. However, it will fundamentally change before then. To learn more about this, we must first explore more details about our Sun.

How Long Has the Sun Been Around?

The Sun formed about 4.6 billion years ago. Scientists believe it was made during the gravitational collapse of matter in this area of space.

What Type of Star Is Our Sun?

Our Sun is a yellow dwarf star. A more scientific name for this type of star is a G-type main-sequence star or G star. The name yellow dwarf star isn’t exactly correct. These stars are actually white or only slightly yellow. However, when we see the Sun through our atmosphere, it has a yellowish tint.

This type of star is fueled by hydrogen. Its core works to turn hydrogen into helium using nuclear fusion. This is a process of combining two or more atom nuclei or subatomic particles. The differing mass between the combining particles results in either the release of energy, or the absorption of energy. In a yellow dwarf star, the energy is released as helium, as long as the star has enough hydrogen.

What Will Happen When the Hydrogen Runs Out of Our Sun?

When a yellow dwarf star runs out of hydrogen, which takes about 10 billion years, it expands, darkens, and cools, turning into a subgiant star.

When this happens to our Sun, the Earth will heat enough to remove the planet’s atmosphere and evaporate the oceans. The atmosphere will become loaded with carbon dioxide.

About one billion years later, the Sun will become a red giant, a huge star with a low mass. It will likely be large enough to envelop Mercury and Venus. Any planet it envelops will probably disintegrate. Even if it does not envelop Earth, it will be close enough to vaporize everything, except for the iron core.

The extra radiation from the Sun will also affect other planets.

In the first few million years as a red giant, the Sun will expand and contract. This may affect its gravitational pull, which could affect the orbit of the remaining planets in our solar system.

The next few hundred million years might see outer planets turning into potentially habitable areas. The extra reach of the Sun will melt the water on their icy surfaces. However, at the end of the red dwarf phase, the Sun will become a white dwarf. This is a small, hot, and dense star that sends out unimaginable levels of heat and radiation. After another billion years, the star will have cooled to more reasonable temperatures. At this point, it could support life very close by. However, it might need to be so close that the white dwarf’s gravitational pull makes life challenging.

One planet has been discovered orbiting a white dwarf star, so it is possible. Luckily, this is all billions of years into the future. By the time our Sun runs out of hydrogen, many experts believe that humans will be long gone.

So, How Will Humanity End?

If experts believe we don’t need to worry about the Sun dying, what issues are they more concerned about?

In most countries, the human birth rate is already below the death rate. While human populations are still on the rise, experts believe that humanity’s population will start to level off around 2100.

Scientists believe that a lowering of sperm quality due to pollution and stress will eventually lead to low birth rates. They also believe that economics is another factor causing a lower birth rate.

Other experts have been calculating probabilities of what will end humans and when. Some believe there is a 19% chance that humanity as we know it will end before the year 2100. They say there is a 5% chance of some catastrophe caused by new molecular weapons or incredibly smart artificial intelligence. Other experts believe there is a 30% chance that humanity will die out in the next 500 years. Others say that climate disasters will end civilization as we know it in as little as 20 to 40 years!

However, it’s important to remember that for thousands of years, if not more, humans have wondered about the end. Many philosophers and religious leaders have even pinned down a date and told everyone to get ready for the apocalypse. (Did anyone else have an “apocalypse party” on December 21, 2012?) Even as far back as the year 365, Hilary of Poitiers said the earth wouldn’t last beyond that year.

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