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Characteristics Of Stars. Galaxy: A collection of stars, gases and dust. Universe: Contains billions of galaxies. The Milky Way galaxy has a whopping circumference of roughly 250-300 thousand light years! Within the main body of the Milky Way there are estimated to be between
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Characteristics Of Stars • Galaxy: A collection of stars, gases and dust. • Universe: Contains billions of galaxies.
The Milky Way galaxy has a whopping circumference of roughly 250-300 thousand light years! Within the main body of the Milky Way there are estimated to be between 200 and 400 billion stars.
Types of Galaxies • 1. Spiral • 2. Elliptical • 3. Irregular
Spiral Galaxies: • Arms spiral outward like a pinwheel • Our galaxy, The Milky Way, is a spiral galaxy
Elliptical Galaxies: • Look like flattened football. • Have billions of stars, but little gas and dust. • Contain the oldest galaxies
Irregular Galaxies • No definite shape • Example: Large Magellanic Cloud
( Light will travel 10 trillionkilometers in one year!) • Scientists use LIGHT YEARS to measure distances in space. A light year is the distance light travels in one year. • Light travels at the speed of 300,000,000meters/second.
Classifying Stars • Stars are classified by 3 Main Characteristics: • 1. Size • 2. Temperature • 3. Brightness
Color reveals the temperature of a star. • Hottest (20,000-50,000*C) • : (10,000*C) • (6,000*C) • (4,000-5,000*C) • (3000*C) Blue White Yellow Red-Orange Red
Brightness of Stars • Apparent Magnitude: Brightness as seen from earth • Absolute Magnitude: Brightness of a star from a standard distance
Hertzsprung-Russell Diagram • A graph plotting brightness and temperature. • 90% of stars are Main Sequence
Lifetimes of Stars • A star’s life depends on its mass. • Stars smaller than the sun live up to 200 billion years. • Medium sized stars like the sun live around 10 billion years. • Stars 15 times more massive than the sun live about 10 million years.
NEBULA • Clouds of gas – made up of elements and compounds • As they spin and condense, heat energy is transformed, forming stars
SUN • Medium sized star • By speed of light, only takes 8.3 minutes to get to Earth from the Sun • Located on the edge of a spiral of the Milky Way galaxy • Center of Solar System
BLACK HOLE • Dense gravity well in space • Light cannot escape the gravitational pull of a black hole • Observed because astronomers can see light and energy being given off by objects being pulled into them • No volume, infinite density • Could be a result of a Supernova explosion