To Mum, 

Merry Christmas

2021.

The life of a small star

A star begins its life as a cloud of hydrogen gas called a nebula. Gravity pulls the cloud together to form a star. This is called a protostar.

Now a brown dwarf star is created. (Brown dwarfs are not brown)

After about a trillion years, the star shrinks into a blue dwarf and then a black dwarf. The remnants will create new stars.

The life of a medium star

A medium star begins its life as a cloud of hydrogen gas called a nebula. Gravity pulls the cloud together to form a star. This is called a protostar.

The star is much bigger and brighter and will have more vibrant colours. It will only last a few billion years.

As the star dies, it starts to swell up as nuclear activity increases. Then in a sudden, a supernova will explode shooting tons of gas and dust for millions of miles. See on the explosion on the next page. 

This is the star swelling up.

BANG!!!

The life of a massive star

A massive star begins its life as a cloud of hydrogen gas called a nebula. Gravity pulls the cloud together to form a star. This is called a protostar.

A massive star will shine intensely bright and is enormous in size. UY Scuti is a good example.

 A star like this will radiate an enormous amount of heat and light. After a few million years  it will grow and explode as bright as a billion suns. There will be two forces. Gravity and radiation. If gravity wins, the star will shrink infinitely smaller than an atom. If radiation wins, the star will be the size of a city.

Black holes and neutron stars

Black holes are weird things scientists are still puzzled about. Einstein predicted that they existed in 1916. However, astronomers didn’t find one until 1972.

The first picture of a black hole looked like this.