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Star Life And Death

This bow shock appeared near a young star in the Orion Nebula. Just like living organisms, stars have a life cycle. In the same way that you are born, develop, age and die, stars do the same things. One big difference is that stars don't need parents. Stars are born from huge clouds of gas and dust. It's amazing how that gas and dust are probably the most boring things in the universe and they can become everything, asteroids, planets and even stars. So you've got that huge cloud of dust and gas. Astronomers call that cloud a nebula. That's when it all starts to happen.


That nebula starts to condense. Slowly but surely over millions of years, gas particles start to cling to each other, then they attract other particles and molecules. The nebula begins to condense and form a ball. That ball is called a protostar. "Proto" is a prefix that means "early" or "before." So a protostar is the first step in becoming a full-fledged burning star.

Start The Fire

After the star finished the protostar phase, it becomes even denser. The heavy elements move to the center of the star while the light gases stay in the star's atmosphere. Those gases are usually hydrogen (H) and helium (He). Then something amazing happens, the nuclear fire begins. The star heats up and the gases ignite. This step in the development process is called the main sequence. If you looked, you would see the birth of the star.

Not All Of Them Make It

In the Solar System section we speak a little about Jupiter. Jupiter is a special planet in that it has a very similar makeup to the Sun. It has a low density and hydrogen and helium are the main components of the atmosphere. It is still missing one thing, nuclear fire. Jupiter could be the star that never was.

Next Stop On Cosmos4Kids Tour
Next Page on stars.
- Introduction
- Requirements
- Luminosity
- Classes
> Development
- Development II
- Black Holes


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Keywords for Review

Kinetic Energy: The energy of an object related to the motion of the object. On a simple level, an object that is not moving has no kinetic energy. An object that is moving has some amount of kinetic energy. The more an object moves, the more kinetic energy it has. An object increases its kinetic energy if it accelerates and increases its velocity. For example, as you increase the temperature of a gas, the molecules become more energetic and the system has an overall increase in kinetic energy. Kinetic Energy=(0.5)* mass * (velocity)2

Exothermic: A chemical reaction that releases energy after the reaction is complete. The energy is usually released as heat, but it can also be released as light or sound. On a small scale, a burning candle releases light and heat because of exothermic reactions as the wax burns. On a large scale, an explosion might occur when blasting with sticks of dynamite (TNT).

Activation Energy: The least amount of energy needed for a chemical reaction to occur. Reactions often require some amount of energy to get moving. For example, placing hydrogen and oxygen gases in a container will not give you water. There is a certain amount of energy required to get the first reaction going. Catalysts are substances that help to lower activation energies so that reactions can proceed.

Viscosity: A term used to measure the fluidity of a liquid. As the attractions between the molecules increase, viscosity increases. Fluids with high viscosities don’t flow easily. Some substances such as honey or sap are very slow moving and have high viscosities. Other fluids such as water or mercury (Hg) have very low viscosities.

Volatile: Volatility is the likelihood that a substance will vaporize (become a gas). Volatility measurements are all about comparing two substances. Substances with a higher vapor pressure are more volatile. Alcohol is more volatile than water because it evaporates at a lower temperature.

Reference Materials

Encyclopædia Britannica:

- Cosmos4Kids: Star Development
- Chem4Kids: Matter
- Chem4Kids: Astrochemistry
- Chem4Kids: Atoms
- Chem4Kids: Hydrogen
- Chem4Kids: Helium
- Geography4Kids: Earth Energy
- Geography4Kids: Solar Radiation
- Physics4Kids: Magnetic Fields
- Physics4Kids: Light

- NASA: Home Page
- NASA: Kids Home Page
- ESA: Home Page
- ESA: Kids Home Page

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