1. STARS Amy Johnson

2. In General Stars are always in the sky, but can only be seen at night when the atmosphere is not so bright The Sun is the closet star to Earth. Stars appear to move across the sky at night due to the rotation of Earth on its axis. Star patterns in the night sky change seasonally due to its revolution.

3. Constellations A group of stars that form patterns in the sky Most visible Ursa Major-Big Dipper Ursa Minor-Little Dipper

4. Starry Colors and Size Color gives clue to the temperature of the star Red is the coolest of the visible stars Yellow stars are medium temperature Bluish-white are the hottest stars Most stars are small Sun is a medium star Betelgeuse – would swallow the first four planets

5. Apparent Magnitude A system used in classifying the brightness of a star from Earth The smaller the number, the brighter the star Sirius, the brightest star, measures a -1.5 Sun measures a –26.7 The sun looks brighter due to its location to Earth

6. The Life of a Star - Birth Begin as gas and dust Gravity causes dust and gas to move close together Temperatures rise and cause atoms in cloud to merge Process called fusion and changes matter to the energy that powers the star

7. The Life of a Star - Evolving Small and medium stars use up the gases in the core and become a giant star Large, cool stars, red in color Sun will become a giant in 5 billion years Will cover orbit of Mercury, Venus and Earth Will be a giant for a billion years

8. Evolving Large stars become supergiants Core collapses, shock wave, explosion, becomes brighter Explosion known as a supernova Might shine more brightly than entire galaxy Released dust and gas may become part of a new star If core remains, it becomes a neutron star If core collapses rapidly, a black hole forms

9. The Life of a Star - Death The outer shell of the star will be lost The core shrinks and is known as a white dwarf White dwarfs are hot and small Eventually, white dwarfs cool and stop shining – black dwarf

10. Galaxies A group of stars, gas, and dust held together by gravity Elliptical Very common, football shaped Spiral Giant pinwheel, some with bar-shaped Irregular Common, smaller, not easily classified

11. Galaxy contents Nebulas- clouds of gas Globular clusters- groups of old stars Open clusters- stars on the spiral disk, newly formed blue stars

12. Milky Way Giant, spiral galaxy Contains hundreds of billions stars, including the Sun Stars revolve around the center of galaxies once every 225 million years the Sun makes a revolution

13. What We See Only part of the Milky Way is visible due to our being in the galaxy Galileo saw the Milky Way in 1609 using a telescope Bigger and brighter than most galaxies in the universe

14. Special stars Supernova - an exploding star Neutron star- remainder of supernova Pulsars-spinning neutron star Quasars- galaxies in the process of forming, incredibly bright Black hole- beyond pulsar that does not allow anything to escape

15. Speed of Light Light travels through space 300,000 km/s Around Earth 7 times in one second You cannot go faster than light Light-years measures distances between galaxies since the distance is so vast The distance light travels in one year = light year (9.5 trillion km)

16. Universe Galaxies contain billions of stars Billions of galaxies make up a universe In 1995, the Hubble Space Telescope discovered over 1,500 galaxies in a tiny sector of the sky