Transcript Our Galaxy and the Universe

AIM: Galaxies and the Universe
Do Now:
Compare the North Star (Polaris)
with the Sun.
I. Nebular Theory
• A nebula is a
cloud of gas and/or
dust in space.
• the stars and
planets form from
this rotating disk of
dust and gases
because of gravity.
II. The Galaxy
• a group of stars,
dust, and gases
held together by
gravity.
Cherry Springs State Park, PA
• the galaxy we live in is called the Milky Way. It
is 100,000 LY across and contains about 300
billion stars.
CGI rendition of our Galaxy
III. The Expanding Universe
video
• The Doppler Effect
- used to determine whether an object in space
are moving away from or toward Earth.
• When applied to light (EMS), the Doppler
Effect shows:
Red Shift when the source is moving away from an
observer. (wavelengths are stretched)
Blue Shift when the source is moving towards an
observer. (wavelengths are compressed)
* Most objects are moving
away from Earth. This
means the universe is
Expanding.
IV. The Big Bang Theory
- states that at one time, the entire universe was
confined to a dense, hot, super-massive ball. About
13.7 billion years ago, a violent explosion occurred,
hurling this material outward creating the universe.
• The red shift of
galaxies supports
the big bang and
the expanding
universe
theories.