Tag Archives: Stars

What Happens When Stars Die?

Stars forming in the Milky Way Galaxy
Stars forming in the Milky Way Galaxy. Image by WikiImages from Pixabay

A star changes into several different phases before its death. Since it is our Sun that brings us life, as well as it being part of the main sequence category of stars, let’s use the sun as our example.

Early On

During the years following the big bang, giant clouds of hydrogen and helium atoms began to form. As the years followed, these elements started to clump together to form balls of hydrogen and helium gas. In other words, they became a mass of balls of gas. When the mass is created, gravity is established and the star cycle begins.

So a star is being formed and as such, our friend gravity keeps getting stronger as the mass of the star keeps getting bigger. When gravity reaches a certain strength, the star will collapse into itself. But wait! This won’t happen because there is a force that will counter the star’s gravitational pull. So what is this mysterious force?

What Stops Stars from Collapsing?

Photo of the Sun by NASA
Our Sun. Photo by NASA on Unsplash

Enter nuclear fusion! This is where the hydrogen and helium atoms combine. Another way of describing this process is when the protons and neutrons, called nuclei of an atom (in this case hydrogen) fuse with the nuclei of another atom (in this case helium) to produce one heavier helium atom

It is that simple… or is it? For the benefit of our audience, we will keep it simple by stating that each hydrogen atom is one ounce (of course this is not the actual weight) and when four of these atoms are combined into one larger atom, the resultant atoms would weigh four ounces. But no! The weight of the combined atom ends up being less than the combined weight of the four separate atoms. So, the mass that escapes when these nuclei combine is in the form of energy

This is a prime example of Einstein’s formula E=mc2, which states that mass and energy are proportionally connected; that is, as mass decreases, energy increases and vice-versa. In the case of nuclear fusion, some of the mass of the helium nucleus is released and converted to energy. 

Another way of describing this process is when a single nucleus combines to form two lighter nuclei. When this happens, energy is released because it gives off more heat than it needs and the result is energy.

If you’d like to get more insight into the actual process of nuclear fusion, then this fun video is for you. 

So the result is that there is a balancing act where the inward pull of the star’s gravity and the outward push of the nuclear fusion process cancel out each of the forces. And that is why the Sun (and all stars) don’t collapse onto themselves (at least as long as there is hydrogen to fuel the nuclear fusion).

Let There Be Light!

If you follow the bible, God said “let there be light”. Maybe it is just a metaphor that explains what this cycle of energy is, but whether you believe in the bible or not, the fact remains that this energy that is produced is in the form of light. And there you have it! Light is created when hydrogen nuclei fuse with helium.

It’s All About Gravity

The Sun, like all stars, has a limited supply of hydrogen in its cores. When the star’s core runs out of hydrogen fuel, gravity takes hold and subsequently, the star will compress. The energy in the form of heat is then generated.

This heat caused the outer layers of the Sun to bulge out or expand across the inner part of our solar system to become what astronomers call a red giant. Big enough to engulf the orbits of Mercury and Venus and even reach Earth. Then, after millions of years, these outer layers of gas will dissipate into the darkness of the universe. 

But let’s get back to what’s left of the star. It will collapse within itself to become a white dwarf, thanks again to gravity. As an example, picture a balloon that contains solid rock (it is just gas, but for this hyper-theoretical explanation, we will use a solid) that is pushed down to the size of a ping-pong ball. 

This is referred to as a change in volume, which means that the same amount of rock in the balloon is condensed to the pong size. In scientific terms, it refers to the volume of the mass that is condensed (to a smaller size) and so, the tiny ball still weighs the same as when it was balloon size. The result is a heavier density of the mass which would be equivalent to that of one teaspoon of the material in the ping-pong ball that could weigh up to 100 tons. Over billions of years, the white dwarf cools and becomes invisible.

What About the Other Stars

Photo of a nebula
Image by Gerd Altmann from Pixabay

Now, let’s take a look at what happens to other stars in the universe. It all depends upon what size the star is during its main life cycle. 

Superlarge stars will change into supernovae, not like our sun which is considered an average star. Its end life cycle will result in a white dwarf as we discussed.  Regardless of the star’s size, all will follow a seven-cycle process. So without further ado, here are the life (and death) cycles of all stars.

1. Giant Gas Cloud

Lagoon Nebula
Lagoon Nebula in the constellation Sagittarius. Image by WikiImages from Pixabay

Nebulas are where stars are born. Similar to a fetus in a womb, the stars grow as the gas molecules work to form them. That is why it is called a gas cloud and we can thank gravity for bringing these molecules together.

2. Protostar

When the gas particles run into each other, heat is created. This result is what scientists call a Protostar – the beginning of a star’s creation. We can view this process via infrared since protostars show up warmer than the other materials in the nebula cloud.

3. T-Tauri Phase

T-Tauri stars are the next phase in the star’s life process, but not strong enough for nuclear fusion to begin. This cycle lasts about 100 million years.

4. Main Sequence

Welcome to the main sequence phase of stars and this is where our Sun is now; otherwise, you would not be here to read this article. Scientifically, it is the process where the core temperature has gone high enough to allow nuclear fusion to begin.

5. Red Giant

When the hydrogen fuel starts to run out, the nuclear fusion process will end its cycle. Now there is nothing to stop the star from condensing into itself because our friend – gravity has complete control with no force to counter it.

As the star contracts inward, the outer layers expand. This expansion is so great that it could reach the orbits of some of its inner planets.

Say hello to the red giant! When stars reach this phase, they appear yellowish since they are cooler than stars that are in their main-sequence stage.

6. The Fusion of Iron

The Helium molecules start combining at the star’s core, causing the core to shrink. When this happens, carbon is fused in and this process continues until the atoms turn into iron. Now the core will collapse as the iron fusion absorbs energy. This in turn causes this red giant to become a supernova., but for medium-sized stars like our Sun, the star will contract and turn into a white dwarf.

7. Supernovae 

Illustration of a supernova explosion
Illustration of a supernova explosion. Image by Gerd Altmann from Pixabay

Some of the most spectacular events in galaxies is the occurrence of supernovae. In this phase, most of the star’s matter is blasted away into space, creating a giant blast that even the human eye can detect if it is within viewing distance.

What is happening is that the star runs out of energy; in other words, it is depleted of its fuel and subsequently collapses into itself, with all the electrons and protons compressing into a neutron and subsequently becoming a neutron star.

8. Stellar Nursery

No doubt you have seen nebulas in photos or maybe through a telescope. These are the stellar nurseries, where remnants of gas and other materials are floating around only to be gathered together again to form new stars.

Illustration of a star's life cycle
Illustration of a star’s life cycle


The Power of the Sun!

Photo of the Sun by NASA
Photo by NASA on Unsplash

How Powerful is the Sun?

Ah, the Sun. We stay warm under it, tan under it and it gives life to every living thing on this planet. But it is 93,000,000 miles away. That is so far that if you were flying to the sun at 550 MPH, it would take you 17 years to get there. If the Space Shuttle, traveling at 27,000 MPH would go there, it would reach the sun in about 156 days.

Let’s Talk Distance First

When you look at the sun, you are actually seeing the way it looked about nine minutes ago. In the photo above, we see a large solar flare extending out from the Sun’s surface, but if you looked at the sun right now, you wouldn’t see the flare. You would have to wait another nine minutes before it would appear.

A more dramatic scenario is that if the Sun blew up right now, we wouldn’t know about it until about nine minutes later, but no worries, the sun won’t leave us for another four or five billion years, so you have time to prepare. These examples boil down to the fact that it takes the light from the Sun that long to reach us.

Don’t Underestimate Its Power

Even at that distance, don’t let your curiosity get the best of you by starring at the sun, or you will go blind! And don’t get silly and stay on the beach without proper lotion or you will be visiting the dermatologist shortly after that. 

We are not saying this to scare you, well, maybe in part, but our main purpose is to give you an idea just how powerful this star, and it is a medium sized star by the way, it really is.

The bottom line is that an object that is 93 million miles away and can still cause this serious damage to every living organism on this planet gives you a good idea of how powerful this gas giant is.

How Big is the Sun When Compared to Other Stars?

We previously mentioned that our Sun is a medium sized star. For a comparison of the size of our Sun relative to other stars in our galaxy, take a look at this video and get ready for a mind-boggle!

Brief Overview of the Sun’s Lifecycle

In about five billion years, this star will have lost all its hydrogen fuel, which is the element that allows the fusion process to proceed. The result is that it will turn into what astronomers call a red giant.

When a star starts turning into a red giant, it begins to expand to an enormous size. So big that its size could engulf virtually all the inner planets in it our solar system. For our solar system, that includes Mercury, Venus, and you got it – Earth. 

As mentioned, we won’t see the Sun’s demise for another 4.5 billion years, so when it begins its red giant cycle, you might want to pack some beers and enjoy watching this event while relaxing on your porch and having a beer or two before you say goodbye! 


The energy of this sun is mind-boggling. It produces energy that is the equivalent of one-trillion megaton bombs per second. Yes, you heard right. That’s 67,000 times as powerful as the bomb that was dropped on Hiroshima and this occurs every second! 

So what is it about this medium-sized star that can be the difference between life and death on Earth? Why is it so powerful? What is it made of? 

Let’s Start with Fusion

Fusion is the process of atoms merging into another atom. In the case of our Sun (and most other stars) four hydrogen atoms fuse into one helium atom, which is the result of extreme heat that causes gravity to allow this phenomenon to occur.  

Not all the mass of the four hydrogen atoms is converted into one helium atom, as the total amount of the mass of the four hydrogen atoms does not equal the total mass of the assimilated helium atom, so something must give. And what gives is energy. A lot of it. About four million times more energy than the burning of coal. 

More precisely, only 71% of the total mass of the four atoms is fused with the hydrogen atom. This is the foundation of Einstein’s formula E=MC2. The more mass that is released, the more energy that is created. So for fusion reactions to occur, Briticana.com sums it up quite clearly: The total mass of the resultant particles is less than the mass of the initial reactants”. Basically, it is saying that mass and energy are different forms of the same thing, so if the mass of an object gives, the result is energy. 

As we mentioned, these fusion reactions occur every second. No wonder we can go blind if we look at the Sun. 

More about how this entire fusion process works can be found here.

The Sun’s Structure

Illustration of he Sun's components
Wikipedia Creative Commons

Imagine a ball of gas that is 865,370 miles in diameter. That’s our Sun. There are no solid materials in this star (or in any star in the universe). Just hot gasses, very hot. 9,900 degrees Fahrenheit hot! 

With that said, the Sun is divided into four layers: the photosphere, chromosphere, corona, and heliosphere. Let’s take a look.

    • Core – The core is where the fusion process occurs. As the hydrogen atoms merge into the helium atoms, energy in the form of light is generated.
    • Radiative Zone – This zone radiates (transfers light and heat).
    • Tachocline – The atoms are radiated through this thin boundary region and then move to the convective zones.
    • Convective Zone – Convection is the process by which less dense material rises. This part of the Sun is much cooler than its inner layers, but the result of this process is where we see the light and feel the heat of the Sun.

There are much brighter stars than the Sun. Some are called “supergiants” or “hypergiants.” These giants can be over 100 times more luminous than our own ball of gas! Now, just imagine how powerful their fusion reactions are! 

Types of Stars

There are many different types of stars in our galaxy. The types of stars are classified by the following criteria:

    • Temperature – Hot stars are blue or white, while cooler stars are orange or red
    • Mass – Massive stars burn out quickly, while less massive ones can last millions of years
    • Spectral Type – Stars can be identified through their colors and temperatures


The Sun is nothing but a huge hot ball of gas, but show some respect, because this great gas ball is what keeps us alive. Amazingly, it supplies life to this planet even though it is 93,000,000 miles away.

The center of the Sun is the core, where the temperatures are millions of degrees. The core’s pressure from gravity causes hydrogen to fuse together to form helium, which is the fusion process. 

The Sun doesn’t have an electrical charge, so it doesn’t produce light on its own. The heat of the core makes the gas around it become extremely hot, and this is what makes it glow.

Our Sun is a type of star called a yellow dwarf. There are other different types of stars that are of different sizes and temperatures. 

So there are many different stars in the universe and our Sun is one of them. They are all so powerful that staring at them for more than a second can make you blind. So accept the fact that this star is powerful, but don’t look up to find out!