Did you know? Stars are one of the main components that make up the structure of the observable universe!

They are hot bodies of glowing gas that start their lives in Nebula, and grow up pretty much like humans. They change through states of life and eventually grow old and die. Most stars change in size, color, and class at least once in their lifetime.

The life cycle of any star, from birth to death, and all the stages in between, will take millions or even billions of years. This is why stars don't seem to change at all, a human lifetime is a fraction of the blink of an eye for this giant.

So, what are the stages of the life cycle of a star? Let's find it out!

A nebula


Nebula is the starting phase for all stars, including our Sun, which begins in clouds of gas and dust. When a dense region in a nebula begins to shrink and warm up, it forms a protostar. As long as materials are still falling inward, an object will always be considered a protostar!

Small or Average Star

Small Star

Once a protostar acquires enough mass, nuclear reactions at the core of stars will provide enough energy to make them shine brightly for many years!

Small or average stars usually last for several billion years as they burn their fuel slowly. A star the size of our Sun will spend around 10 billion years in this phase.

Red Giant

Red Giant

After the main sequence phase, a star will turn into a red giant. It happens when helium builds up and the hydrogen fuel runs out. As a result, the internal nuclear reactions in it will stop, and without this, the star begins to pull things inwards. Probably, it can also gobble up the planets surrounding it!

Planetary Nebula

Planetary Nebula Star

A planetary nebula is an expanding plasma that is cast off towards the end of a low-mass star life. It becomes highly unstable and starts to pulsate, which results in the outer layers drifting away from the star.

White Dwarf

White Dwarf Star

As the outer layers drift away from the star, the remaining core shines brightly. Now, the core becomes a white dwarf star. It’s very hot but there are no longer nuclear reactions taking place inside.

Large Star

Large Star

While small or average stars usually lead rather peaceful lives, large, or massive stars burn their fuel of hydrogen much faster than smaller stars. They may only last a few hundred thousand years.

Red Supergiant

Red Supergiant star

Red supergiants are supergiant stars of the K-M spectrum type and luminosity class I. They are similar to red giants, and are the largest stars in the universe in terms of physical size even if they are not the most massive.



A supernova is a very energetic explosion of a large, massive star at a certain point in its life cycle. It is caused by the collapse of a gravitational core which can emit more energy than a nova and its brightness can last for several months.

Neutron Star

Neutron Star

After the supernova explodes, the star's core is left behind the form of either a black hole or a neutron star. A cubic metre of a neutron star would weigh just less than 400 billion tons, making their surface gravity truly immense.

Black Hole

Black Hole

Now, what’s left after the supernova?  Yup, it becomes a black hole!

A black hole literally pulls the space around them. It needs to have a large amount of mass in a super small space to have the required gravity to pull in light.

So, have you understood about the life cycle of a star? Actually, by understanding the stars,  it helps us understand the universe as well. So, let's appreciate more about the stars and learn more about them!

Interested to learn more about the life cycle of a star? Head over to Assemblr EDU's Topics page, and get ready to learn about the stars with an impressive visualization!

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