Name: _____________________ Date: _________________

Grade 9 AstronomyLesson 9 – Stars, Galaxies and the Big Bang

Star Life Cycle

- Stars form and come to an end like living things. There are several stages that all stars have in common and also many differences depending on the type of star that forms.

- All stars form from massive clouds of gasses and dust called a _______________.

- Nebulae are made of mostly hydrogen and helium.

The Protostar

- Gases in a nebula are not evenly distributed. Regions of higher density pull in gas and dust to form a tightly packed sphere of matter called a ________________ .

- This mass will continue to suck in matter for several million years until it gets dense and hot enough for ____________ fusion to begin.

Star Mass

- All stars begin in the same way but their end depends on their ________ . The more mass a star has the faster it will ‘burn’ and the ___________ it’s life will be.

- The Hertzsprung-Russel diagram shows that with most stars (the Main Sequence) the larger they are, the hotter and brighter they will also be.

Death of a Star

- The end of a star’s life depends on its mass.

Star Clusters

- Star clusters are groups of stars that form from the same ______________.

- Small groups of 6 to a few thousand stars are called open clusters.

- Massive groups of thousands to millions of stars grouped in a ball are called globular clusters.

- A ____________ is a collection of thousands of star clusters with billions of stars all held together by gravity.

Edwin Hubble

- In the 1920’s Edwin Hubble discovered that other ____________ besides our own Milky Way exist. His discovery made the universe a lot bigger than anyone could imagine before.

Galaxies

- Galaxies come in a variety of shapes and sizes which Hubble grouped into categories. The Milky Way is a spiral galaxy.

- At the center of most galaxies is a super-massive __________ hole!

Quasars

- A quasar is a _____________ galaxy with a very luminous central region. They emit hundreds of times the amount of energy that our galaxy does.

The Big Bang

- Edwin Hubble also determined that all the galaxies are moving __________ from each other, which means that the universe is expanding.

- This observation combined with countless others support the idea that at one point all matter, time and space were all compressed into a single point before it exploded. This is the BIG BANG Theory!