Electromagnetic Waves with Wavelengths 1 nm = 1 x 10-9 meters

What can LIGHT tell us about the objects in space that produce them? The composition of the gas, by comparing to known gases in the lab The temperature of the gas, generally the spectral lines of various elements become more prominent at certain temperatures The motion of the object producing the lines, either towards us or away from us. This is known as the Doppler Effect

There are 3 types of light spectrums that we see in space: #1) A continuous spectrum is produced by a HOT glowing solid (Bright line) (Dark line)

#2) A bright line spectrum or emission spectrum is produced when a low density gas (like in a nebula) is HOT and glows (Bright line) Each element has its own characteristic bright line spectrum (Dark line)

Emission Spectrum (Bright-line)

#3) An absorption spectrum or dark line spectrum is produced when a gas (in space) comes between the observer and the source of light (Bright line) (Dark line)

The Doppler Effect in sound waves

Galaxy is moving away from us Normal line position

Would this be a blue shift or red shift? So is this galaxy moving towards or away from us? Would this be a blue shift or red shift?

Would this be a red shift or blue shift? So is this galaxy moving towards or away from us? Would this be a red shift or blue shift?

These galaxies all show high red shifts Farthest look yet into space

Why are all galaxies Red Shifted? Universe began with the Big Bang about 13-14 billion years ago The universe is expanding! Cosmic Background Radiation is the “echo” of the Big Bang Will the Universe expand forever or collapse in a Big Crunch? Oscillating Universe? The expansion of the Universe is speeding up! Dark Energy? Dark Matter? Big Freeze?

All stars are contained in galaxies Our own Milky Way galaxy contains around 200 billion suns This is what our own galaxy (the Milky Way) might look like if we could get far enough outside of it and view it face on

Top view of what Milky Way would look like

Spiral Galaxy (viewed face on)

Spiral Galaxy (viewed edge-on)

Elliptical Galaxies – these galaxies have no spiral arms

Irregular Galaxies

Stable main sequence star

Fusion Hydrogen + Hydrogen makes Helium + energy Fusion is what makes all stars SHINE

Luminosity ….Means how BRIGHT a star APPEARS BIG stars appear brighter CLOSE stars appear brighter HOT stars appear BLUE

Betelgeuse in Orion is a Supergiant (red) Rigel is BLUE

Know this sequence of events in the lives of stars! Medium size Large Size Know this sequence of events in the lives of stars!

H-R Diagram Most stars spend most of their lives on the MAIN SEQUENCE Dying Stars: Red Giants and Super Giants Dead Stars: White Dwarfs, Black Dwarfs, Neutron Stars, Black Holes

Dying stars Young & Middle aged stars Dead stars

Milky Way: Our Galaxy

Pointer Stars point to Polaris

Polaris and Circumpolar stars

Cassiopeia the Queen

Cepheus the King

Orion the Hunter Left shoulder star is Betelgeuse, red giant, 12th brightest star Right knee star is Rigel (blue-white), 7th brightest star

Sagittarius (“teapot”)

Where am I?

In….Red Hook High School

In…Red Hook Village

In….Upstate NY

In…..Eastern North America

On…. Planet Earth

In…. The Solar System

Nearest Star to the Sun

In…. The Solar Neighborhood

In… The Milky Way Galaxy

Nearest Neighbor Galaxy

In… The Local Group of Galaxies

In… The Local Supercluster of Galaxies

Nearest Neighbor Superclusters

In the Universe