Astronomy II - SeeS Galaxies and Distant Objects

Stars  Large ball made up of burning Hydrogen  Our Sun is a Star

How do we know what a Star is Made of?  Astronomers study spectral lines.

Constellations  A Constellation is a picture made of stars created from our imagination.  Astronomer’s use Greek pictures to name locations of stars in the sky.

Galaxy  A Galaxy is made up of billions and billions of stars.  The Galaxy we live in is called the Milky Way.  There are billions and billions of Galaxies in the Universe.

How do we know the distance to Stars?  Astronomers use a process called Parallax to find the distance to our closest stars.

Parallax  The shift of an object against a background caused by a change in an observer’s position

Parallax  Since the Earth moves, we can see parallax with stars. July Earth Sun January Star A Star B Star C

How do we know the distance to Galaxies?  Astronomer’s use a process called Standard Candle Method.  They compare two objects of the same brightness.

Distance across Earth - 3, 959 Miles

Distance to closest star light years

Distance across Milky Way - 100,000 light years

Distance from Earth to edge of Universe - 46 billion light years