What’s in the Night Sky?

How are stars classified? COLOR TEMPERATURE BRIGHTNESS SIZE COMPOSITION

COLOR AND TEMPERATURE The color of a star helps determine its temperature RED,ORANGE, & YELLOW stars have a COLD TEMPERATURE BLUE, BLUE-WHITE, & WHITE stars have a WARM TEMPERATURE

BRIGHTNESS The brightness of a star depends on its SIZE and TEMPERATURE. Apparent Brightness – brightness as seen from Earth Absolute Brightness – the brightness a star would have if it were at a standard distance from Earth.

CHEMICAL COMPOSITION Stars are made up of mostly Hydrogen and other elements. SPECTOGRAPHS are used to determine the elements found in stars.

MEASURING DISTANCE TO THE STARS Light-Year: the distance that light travels in one year Parallax: the apparent change in position of an object when you look at it from different places.

Stars – How are stars created?

MAIN SEQUENCE STARS The 1st and longest phase of a star’s life cycle is called the MAIN SEQUENCE. During this stage, the size of the star will change very little

RED GIANT & SUPER GIANTS 2nd Stage of a star A large, reddish star late in its life cycle It expands and cools once it uses all its hydrogen. Loss of hydrogen causes the star to shrink Red Giants can be 10 or more times bigger than the sun Super Giants are 100 times bigger than the sun

White Dwarfs Final stage of a star Eventually the outer parts expand and drift into space creating a PLANETARY NEBULA The blue-white core of the star that is left is a WHITE DWARF After billions of years, the white dwarf stops glowing and what is left is a BLACK DWARF

SUPERNOVAS: When stars get old When a Super GiaNT star runs out of fuel it explodes suddenly. This is called a SUPERNOVA SUPERNOVAS: When stars get old

NEUTRON STARS Formed after a supernova Gravity collapses a star to the point at which The old stars particles form together to create a neutron star NEUTRON STARS

BLACK HOLES Occurs when the center of a star that has a very high mass collapses and causes the star to contract The force of the contraction crushed the center of the star and leaves a black hole It is so massive that light cannot escape