Stars are among the most identifiable objects in the sky. They illuminate the darkness and dot the galaxy. Stars are born in a dusty cloud and eventually form a mass of gas and chemicals that burn brightly in the sky. But in the end, all stars, no matter how big and bright, must also die.
How long do stars live?
The sun, for example, is a 4.5 billion year old star that will continue its lifespan for another 10 billion years. The sun is illuminated by a combination of hydrogen and helium in a reaction called fusion. At some point, the sun will use up all the hydrogen in its core and begin to die out.
(Credit: Lukasz Pawel Szczepanski/Shutterstock)
A star must die
According Nasa, the sun will no longer have enough heat to sustain it against gravity, and as a result, it turns into a fiery red ball burning from above that will eventually consume the Earth. According to NASA, “the atmosphere [of the sun] will envelop the Earth, and our planet will be consumed in a fiery death.”
Learn more: How will life on Earth end?
The sun’s collapse happens over billions of years, but it’s no less dramatic. Once gravity causes a star to collapse in on itself, it will take another 100 million years for a star to deflate and form a persistent red cloud. Eventually, about 10 million years later, all that’s left is a hot core of carbon and gases that form a “planetary nebula.” As the star fades, it will dim into a white dwarf planet.
What happens when a star dies?
But while the sun may seem huge from our vantage point, it’s considered a baby in terms of stars. And the biggest stars come out with a bigger bang. The death of a larger star, say, about 10 times brighter than the sun, results in a supernova explosion, the largest explosion we humans have ever seen. And supernova explosions happen in seconds.
Supernova Star vs Smaller Star Explosions
According Nasa, a supernova star is considered the “last hurrah of a dying star”. Nuclear fuel burning at the core of a massively bright star causes so much heat, pressure and energy that the star is not able to collapse like a smaller star because the intense pressure at its core continues to struggle against gravity pushing inward.
Eventually, just like the smallest star, a supernova’s fuel will run out and gravity will succeed in crushing the star’s core. It happens so quickly that it creates intense shock waves throughout the galaxy. It can even cause a black hole to form, the densest part of the solar system when gravity pulls so hard that not even light can escape.
Learn more: How many ways can the sun kill us?
Explosive Supernovas
In November 2022, the The Hubble Space Telescope captured a supernova explosion that occurred 11 billion years ago, when the universe was one-fifth the age it is today. The telescope was able to take images at different stages of the explosion, which showed it going from hot to cold in a series of bright blue to red images that appeared before it died down. It was the first time that we could witness the death of a massive star.
Supernova explosions are not only important because they are the end of a dying star. They also create the perfect breeding ground for future stars. Without them, space would have neither carbon nor oxygen, the elements that make life on Earth possible. The stars live, then they die, but in the meantime they magically light up the sky above.
Learn more: A Sun-Like Star Has Discovered an Orbiting Black Hole