When exactly will the sun die?

Although our star's final death will occur in trillions of years, the "life" of the Sun in its current phase, known as its "main sequence" - in which the nuclear fusion of hydrogen allows it to radiate energy and provide enough pressure to prevent the star from collapsing under its own mass - it will end in "just" 5 billion years.

"The Sun is just under 5 billion years old," said Paola Testa, astrophysicist of the Center for Astrophysics, a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. "It is a kind of middle-aged star, in the sense that its life will be on the order of 10 billion years or so."

After the Sun has burned off most of the hydrogen in the its core, it will move on to its next phase as a red giant. At this point about 5 billion years into the future, it will stop generating heat through nuclear fusion and its core will become unstable and contract, according to NASA. Meanwhile, the outer part, which will still contain hydrogen, will expand, gradually engulfing neighboring planets, such as Mercury and Venus, and increase the solar winds to the point of canceling the Earth's magnetic field and removing its atmosphere.

Graphic reconstruction of a solar storm hitting Mars - Credits: NASA Of course, this will almost certainly be bad news for any life left on our planet at that point - assuming someone survived the 10% increase in the Sun's brightness that is expected to vaporize Earth's oceans in 1 / 1.5 billion years, according to a 2014 study published in Geophysical Research Letters. Within a few million years of this initial expansion, the Sun is also likely to consume the rocky remnants of the Earth, according to a 2008 study published in the Monthly Notices of the Royal Astronomical Society.

The Sun will then begin to melt the helium left over from the fusion of hydrogen into carbon and oxygen, before collapsing to its core, leaving behind a stunning planetary nebula - a glowing shell of hot plasma and remnant - in its outer layers as it shrinks to an incredibly dense, significantly hotter, Earth-sized stellar corpse known as a white dwarf. The nebula will only be visible for about 10,000 years, Testa said - a blink of an eye in cosmic time. From there, what remains of the Sun will pass trillions of years to cool before becoming a non-emitting object.