1. The Interstellar Medium
10-1

2. Question
We have heard the term “vacuum of space”, what does this mean? Is it really empty?

3. Interstellar Medium Gas and dust between stars
Place where stars are born and the stuff of dead stars
Found within galaxies and just outside

5. Orion A great place to observe interstellar medium
Look carefully at Orion’s sword, you will see one of the stars has a hazy cloud

6. Nebulae: clouds of gas and dust

7. Interstellar dust Dust in space Constantly spreading through space
Makes up 1% of the interstellar medium
Causes two different phenomena
Interstellar extinction
Interstellar reddening

8. Interstellar extinction
Distant stars look fainter because of interstellar dust in the way
The star becomes about 2 magnitudes fainter per thousand parsecs the star is away from the sun
Ex pc= 2 mag fainter
2000 pc = 4 mag fainter

9. Interstellar reddening
Dust particles scatter light making a blue star look reddish