stars

  • Starter Characteristics

    • Introdution to Stars

    • There are an estimated 300 sextillion stars in the universe (that's 3 followed by 23 zeros! )

    • Stars are giant balls of gas held together by gravity 

    • They produce their owna light and heat through nuclear fusion

  • What are stars made out of?

    • Stars are mostly made of hydrogen ( about 70%) and helium (about 28%) 

    • The remaining 2% is made up of other elements 

    • The gas in stars is so hot it’s in a state called plasma

    • In plasma, electrons are separated from the nuclei of atoms

  • How stars make energy 

    • Stars produce energy through nuclear fusion

    • This happens in the stars' core, where it’s extremely hot and dense

    • Hydrogen atoms combine to form helium

    • This releases a lot of energy as heat and light 

    • The equation for this process is: 4 1H > 4He + 2e+ + 2v + energy 

    • About 0.7% of the mass is converted to energy ( E = mc2)

  • Star Brightness: Magnitude

    • We measure star brightness using magnitude

    • Apparent magnitude: how bright a star looks from Earth

    • Absolute magnitude: how bright a star is

    • Lower numbers mean brighter stars

    • A difference of 5 in magnitude = 100 times brighter 

  • Star Colors and Temperatures 

    • A star's color tells us about its temperature 

    • Blue stars are the hottest (about 30,000 K)

    • White stars are very hot (about 10,000 K)

    • Yellow stars like our Sun are medium (about 6,000 K) 

    • Orange stars are cooler (about 4,000 K)

    • Red stars are the coolest (about 3,000 K)

  • The Hertzsprung-Russell Diagram

  • This important chart shows the relationships between a star’s brightness and temperature. 

    • It helps scientists understand how stars change over time 

    • The vertical axis shows brightness 

    • The horizontal axis shows temperature

  • Types of stars

    • Main sequence stars: These are the Most common stars, like our Sun

    • Red giants: Large, cooler old stars 

    • White dwarfs: Small, dense, hot stars about Earth’s size

    • Neutron stars: Incredibly dense stars left after supernovas

    • Variable stars: Stars that change in brightness over time 

    • There are two types of variable stars: pulsating and eclipsing 

    • Two stars are taking turns blocking each other's light

  • Star group: Binary System and Clusters

    • Binary systems: two stars orbiting each other

    • Open clusters: loose groups of young stars

    • Globular cluster: dense, spherical collections of old stars

  • Galaxies: The largest Star Groups 

    • Galaxies are huge collections of stars, gas, and dust 

    • Our galaxy is called the Milky Way 

    • Contains hundreds of billions of stars 

  • What are constellations 

    • Constellations are patterns of stars in the night sky 

    • Astronomers recognize 88 official constellations

    • Ancient people used them for navigation and storytelling

    • Stars in a constellation aren’t close to each other in space

  • Famous constellations

    • Ursa Major (Great Bear): Contains The Big Dipper

    • Orion (The Hunter): Has three bright stars in a line (Orion’s Belt)

    • Cassiopeia (The Queen): Looks like a W or M in the sky 

  • The importance of Contallitions

    • Helped astronomers map and navigate the sky 

    • Used to locate and communicate about celestial objects

    • Connect us to ancient myths and stories 

    • Inspire curiosity about the universe

  • Stargazing Tips 

    • Use your first to measure sky distances (covers about 10)

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