Is the Sun technically alive?
Answer. Kat - No it isn't. It is a big flaming ball of exploding helium or hydrogen, one of the two.
Earth may survive the event, but will not be habitable. Once the sun completely runs out fuel, it will contract into a cold corpse of a star – a white dwarf.
The Sun survives by burning hydrogen atoms into helium atoms in its core. In fact, it burns through 600 million tons of hydrogen every second. And as the Sun's core becomes saturated with this helium, it shrinks, causing nuclear fusion reactions to speed up - which means that the Sun spits out more energy.
When the Sun exhausts its store of nuclear fuel, some 5 billion years from now, it will evolve into a bloated red giant, gobbling up Mercury and Venus, and scorching the Earth. After ejecting its outer layers in the form of a colourful planetary nebula, the Sun will then be compressed into a tiny white dwarf star.
Nothing is more important to us on Earth than the Sun. Without the Sun's heat and light, the Earth would be a lifeless ball of ice-coated rock. The Sun warms our seas, stirs our atmosphere, generates our weather patterns, and gives energy to the growing green plants that provide the food and oxygen for life on Earth.
Within a few days, however, the temperatures would begin to drop, and any humans left on the planet's surface would die soon after. Within two months, the ocean's surface would freeze over, but it would take another thousand years for our seas to freeze solid.
Take a deep breath—Earth is not going to die as soon as scientists believed. Two new modeling studies find that the gradually brightening sun won't vaporize our planet's water for at least another 1 billion to 1.5 billion years—hundreds of millions of years later than a slightly older model had forecast.
Humanity has a 95% probability of being extinct in 7,800,000 years, according to J. Richard Gott's formulation of the controversial Doomsday argument, which argues that we have probably already lived through half the duration of human history.
Astronomers estimate that the sun has about 7 billion to 8 billion years left before it sputters out and dies.
Fires can't start in space itself because there is no oxygen – or indeed anything else – in a vacuum. Yet inside the confines of spacecraft, and freed from gravity, flames behave in strange and beautiful ways. They burn at cooler temperatures, in unfamiliar shapes and are powered by unusual chemistry.
What fuels our sun?
Through nuclear fusion, the sun is constantly using up the hydrogen in its core:Every second, the sun fuses around 620 million metric tons of hydrogen into helium. At this stage in the sun's life, its core is about 74% hydrogen.
If we were above the atmosphere, say on the International Space Station and looked at the sun (through our filtered visor), the sun would appear white! Why? Because though the sun emits strongest in the green part of the spectrum, it also emits strongly in all the visible colors – red through blue (400nm to 600nm).
It is the pull of the Moon's gravity on the Earth that holds our planet in place. Without the Moon stabilising our tilt, it is possible that the Earth's tilt could vary wildly. It would move from no tilt (which means no seasons) to a large tilt (which means extreme weather and even ice ages).
In short, the sun is getting farther away from Earth over time. On average, Earth is about 93 million miles (150 million kilometers) from the sun, according to NASA (opens in new tab). However, its orbit is not perfectly circular; it's slightly elliptical, or oval-shaped.
Eventually, the fuel of the sun - hydrogen - will run out. When this happens, the sun will begin to die. But don't worry, this should not happen for about 5 billion years. After the hydrogen runs out, there will be a period of 2-3 billion years whereby the sun will go through the phases of star death.
Eternal night would fall over the planet and Earth will start traveling into interstellar space at 18 miles per second. Within 2 seconds, the full moon reflecting the sun's rays on the dark side of the planet would also go dark.
The gravitational pull of the moon moderates Earth's wobble, keeping the climate stable. That's a boon for life. Without it, we could have enormous climate mood swings over billions of years, with different areas getting extraordinarily hot and then plunging into long ice ages.
Although you might think it would be cool, humans could not live on the moon! (Maybe one day in the future…) The moon has almost no atmosphere, so there's no air for us to breathe. There is no water on the moon either, and we need to drink water to survive.
Potential for Life
The surface of Pluto is extremely cold, so it seems unlikely that life could exist there. At such cold temperatures, water, which is vital for life as we know it, is essentially rock-like. Pluto's interior is warmer, however, and some think there could even be an ocean deep inside.
If the sun was no more, then Earth would be drawn to a new centre of gravity. The gravity of Earth and the rest of the solar system would be affected and – with there being no constant energy supply from the sun – Earth would start drifting into space.
Will the Sun eventually burn out?
In about 5.5 billion years the Sun will run out of hydrogen and begin expanding as it burns helium. It will swap from being a yellow giant to a red giant, expanding beyond the orbit of Mars and vaporizing Earth—including the atoms that make-up you.
Since there is effectively zero friction in space and because there is nothing grabbing the sun, there is nothing stopping the sun. Therefore, it just keeps on spinning under its own angular momentum. This effect is not some special property of the sun. All planets, moons, and stars spin for this same reason.
It still has about 5,000,000,000—five billion—years to go. When those five billion years are up, the Sun will become a red giant.
So, before the Sun, there must have existed a star - probably an intermediate mass star - which evolved to become a giant, made barium in its interior, then lost its envelope through a massive wind into the interstellar medium, and that material was incorporated into the protosun.
The Sun's gravitational force is like the tetherball rope, in that it constantly pulls Earth toward it. Earth, however, like the tetherball, is traveling forward at a high rate of speed, which balances the gravitational effect. This means that the planet neither flies out into space nor falls into the Sun.
The Sun formed about 4.6 billion years ago in a giant, spinning cloud of gas and dust called the solar nebula. As the nebula collapsed under its own gravity, it spun faster and flattened into a disk.